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  • 1.
    Bergkvist, Max
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Henricson, Joakim
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Iredahl, Fredrik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Assessment of microcirculation of the skin using Tissue Viability Imaging: A promising technique for detecting venous stasis in the skin2015Inngår i: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 101, s. 20-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: : Venous occlusion in the skin is difficult to detect by existing measurement techniques. Our aim was to find out whether Tissue Viability Imaging (TiVi) was better at detecting venous occlusion by comparing it with results of laser Doppler flowmetry (LDF) during graded arterial and venous stasis in human forearm skin. Methods: : Arterial and venous occlusions were simulated in 10 healthy volunteers by inflating a blood pressure cuff around the upper right arm. Changes in the concentration of red blood cells (RBC) were measured using TiVi, while skin perfusion and concentration of moving red blood cells (CMBC) were measured using static indices of LDF during exsanguination and subsequent arterial occlusion, postocclusive reactive hyperaemia, and graded increasing and decreasing venous stasis. Results: : During arterial occlusion there was a significant reduction in the mean concentration of RBC from baseline, as well as in perfusion and CMBC (p less than 0.008). Venous occlusion resulted in a significant 28% increase in the concentration of RBC (p = 0.002), but no significant change in perfusion (mean change -14%) while CMBC decreased significantly by 24% (p = 0.02). With stepwise increasing occlusion pressures there was a significant rise in the TiVi index and reduction in perfusion (p = 0.008), while the reverse was seen when venous flow was gradually restored. Conclusion: : The concentration of RBC measured with TiVi changes rapidly and consistently during both total and partial arterial and venous occlusions, while the changes in perfusion, measured by LDF, were less consistent This suggests that TiVi could be a more useful, non-invasive clinical monitoring tool for detecting venous stasis in the skin than LDF.

  • 2.
    Bergkvist, Max
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Zötterman, Johan
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Henricson, Joakim
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Hjärt- och Medicincentrum, Hudkliniken i Östergötland.
    Iredahl, Fredrik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Vascular Occlusion in a Porcine Flap Model: Effects on Blood Cell Concentration and Oxygenation.2017Inngår i: Plastic and reconstructive surgery. Global open, ISSN 2169-7574, Vol. 5, nr 11, artikkel-id e1531Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Venous congestion in skin flaps is difficult to detect. This study evaluated the ability of tissue viability imaging (TiVi) to measure changes in the concentration of red blood cells (CRBC), oxygenation, and heterogeneity during vascular provocations in a porcine fasciocutaneous flap model.

    Methods: In 5 pigs, cranial gluteal artery perforator flaps were raised (8 flaps in 5 pigs). The arterial and venous blood flow was monitored with ultrasonic flow probes. CRBC, tissue oxygenation, and heterogeneity in the skin were monitored with TiVi during baseline, 50% and 100% venous occlusion, recovery, 100% arterial occlusion and final recovery, thereby simulating venous and arterial occlusion of a free fasciocutaneous flap. A laser Doppler probe was used as a reference for microvascular perfusion in the flap.

    Results: During partial and complete venous occlusion, increases in CRBC were seen in different regions of the flap. They were more pronounced in the distal part. During complete arterial occlusion, CRBC decreased in all but the most distal parts of the flap. There were also increases in tissue oxygenation and heterogeneity during venous occlusion.

    Conclusions: TiVi measures regional changes in CRBC in the skin of the flap during arterial and venous occlusion, as well as an increase in oxygenated hemoglobin during venous occlusion that may be the result of reduced metabolism and impaired delivery of oxygen to the tissue. TiVi may provide a promising method for measuring flap viability because it is hand-held, easy to-use, and provides spatial information on venous congestion.

  • 3.
    Droog Tesselaar, Erik
    et al.
    Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US. Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Flejmer, Anna M.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Onkologiska kliniken US.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Dasu, Alexandru
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US. The Skandion Clinic, Uppsala, Sweden.
    Changes in skin microcirculation during radiation therapy for breast cancer2017Inngår i: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 56, nr 8, s. 1072-1080Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract:

    Background: The majority of breast cancer patients who receive radiation treatment are affected by acute radiation-induced skin changes. The assessment of these changes is usually done by subjective methods, which complicates the comparison between different treatments or patient groups. This study investigates the feasibility of new robust methods for monitoring skin microcirculation to objectively assess and quantify acute skin reactions during radiation treatment.

    Material and methods: Laser Doppler flowmetry, laser speckle contrast imaging, and polarized light spectroscopy imaging were used to measure radiation-induced changes in microvascular perfusion and red blood cell concentration (RBC) in the skin of 15 patients undergoing adjuvant radiation therapy for breast cancer. Measurements were made before treatment, once a week during treatment, and directly after the last fraction.

    Results: In the treated breast, perfusion and RBC concentration were increased after 1–5 fractions (2.66–13.3 Gy) compared to baseline. The largest effects were seen in the areola and the medial area. No changes in perfusion and RBC concentration were seen in the untreated breast. In contrast, Radiation Therapy Oncology Group (RTOG) scores were increased only after 2 weeks of treatment, which demonstrates the potential of the proposed methods for early assessment of skin changes. Also, there was a moderate to good correlation between the perfusion (r = 0.52) and RBC concentration (r = 0.59) and the RTOG score given a week later.

    Conclusion: We conclude that radiation-induced microvascular changes in the skin can be objectively measured using novel camera-based techniques before visual changes in the skin are apparent. Objective measurement of microvascular changes in the skin may be valuable in the comparison of skin reactions between different radiation treatments and possibly in predicting acute skin effects at an earlier stage.

  • 4.
    Elawa, Sherif
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Mirdell, Robin
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för medicin och hälsa. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Medicinsk strålningsfysik.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    The microvascular response in the skin to topical application of methyl nicotinate: Effect of concentration and variation between skin sites2019Inngår i: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 124, s. 54-60Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background

    Methyl nicotinate (MN) induces a local cutaneous erythema in the skin and may be used as a local provocation in the assessment of microcirculation and skin viability. The aims were to measure the effects of increasing doses of MN, to find the concentration that yields the most reproducible effect from day to day and between sites, and to study the variation between skin sites.

    Methods

    Microvascular responses to topically applied MN at different concentrations were measured in 12 subjects on separate days and on contralateral sides, using laserspeckle contrast imaging (LSCI). MN effects were measured in four different body sites.

    Results

    At 20 mmol/L, the response to MN was most reproducible day-to-day and site-to-site, and resulted in a plateau response between 5 and 20 min after application.

    The skin region of the lower back had a lower perfusion value compared to the epigastric region (p = 0.007). When responses were compared to nearby, unprovoked areas, a significantly larger increase in perfusion was seen in the forearm, compared to all other anatomical sites (p < 0.03).

    Conclusion

    A concentration of 20 mmol/L MN generated the most reproducible microvascular response in the skin. The response varies between different body sites.

  • 5.
    Elmasry, Moustafa
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Plastic Surgery Unit, Surgery Department, Suez Canal University, Egypt.
    Mirdell, Robin
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Medicinsk strålningsfysik. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Steinvall, Ingrid
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Laser speckle contrast imaging in children with scalds: Its influence on timing of intervention, duration of healing and care, and costs2019Inngår i: Burns, ISSN 0305-4179, E-ISSN 1879-1409, Vol. 45, nr 4, s. 798-804Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [sv]

    Background

    Scalds are the most common type of burn injury in children, and the initial evaluation of burn depth is a problem. Early identification of deep dermal areas that need excision and grafting would save unnecessary visits and stays in hospital. Laser speckle contrast imaging (LSCI) shows promise for the evaluation of this type of burn. The aim of this study was to find out whether perfusion measured with LSCI has an influence on the decision for operation, duration of healing and care period, and costs, in children with scalds.

    Methods

    We studied a group of children with scalds whose wounds were evaluated with LSCI on day 3–4 after injury during the period 2012–2015. Regression (adjustment for percentage total body surface area burned (TBSA%), age, and sex) was used to analyse the significance of associations between degree of perfusion and clinical outcome.

    Results

    We studied 33 children with a mean TBSA% of 6.0 (95% CI 4.4–7.7)%. Lower perfusion values were associated with operation (area under the receiver-operating characteristic curve 0.86, 95% CI 0.73–1.00). The perfusion cut-off with 100% specificity for not undergoing an operation was ≥191 PU units (66.7% sensitivity and 72.7% accurately classified). Multivariable analyses showed that perfusion was independently associated with duration of healing and care period.

    Conclusion

    Lower perfusion values, as measured with LSCI, are associated with longer healing time and longer care period. By earlier identification of burns that will be operated, perfusion measurements may further decrease the duration of care of burns in children with scalds.

  • 6. Bestill onlineKjøp publikasjonen >>
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Hand och plastikkirurgi. Linköpings universitet, Hälsouniversitetet.
    On microvascular blood flow assessment with the new microdialysis urea clearance technique2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The aim of this thesis was to develop and evaluate a new way of monitoring blood flow with microdialysis. A thin catheter consisting of a semipermeable membrane is implanted in the tissue being studied. The catheter is perfused by a solution that closely resembles interstitial fluid, and small water-soluble substances are allowed to diffuse passively through the pores of the membrane with the aim at reaching equilibrium with the surrounding tissue.  The minimally invasive character of microdialysis, and its ability to sample from the organ being studied, make microdialysis attractive in most research settings as well as for clinical surveillance. It has, however, become increasingly evident that microdialysis under conditions of non-equilibrium - for example, fluctuating regional blood flow, will alter the results gained. We have therefore aimed to explore the possibilities of developing a new marker of blood flow that will yield information about changes in blood flow that occur in the area of the microdialysis catheter itself.

    We hypothesised that the changes in the diffusion of exogenous urea could be used as markers of changes in tissue blood flow. The theoretical basis for this approach is that the mass transfer of urea will increase across the dialysis membrane secondary to increased blood flow. As removal of urea from the vicinity of the dialysis membrane increases with increased blood flow, the concentration gradient of urea between the perfusate and tissue will also increase. This in turn will result in a greater loss of urea from the perfusate. The changes noted in retrieval of urea from dialysate by the system are therefore thought to be inversely related to changes in blood flow. We tested our hypothesis in two species of animal (rat and pig) and in man, and in three organ systems (muscle, liver, and skin), and present four papers that indicate that the urea clearance technique provides reliable and reproducible results. The technique was evaluated against conventional metabolic markers (lactate and glucose), the ethanol clearance technique (microdialysis), laser Doppler perfusion imaging (LDPI), and polarisation light spectroscopy (TiVi).

    We present evidence that the urea clearance technique can be used to assess blood flow in the organs studied reliably and reproducibly with microdialysis. The microdialysis technique is minimally invasive and safe for the recipient, and catheters can easily be implanted during operation to monitor organs at risk. Urea is easily analysed as a standard assay among other “basic” metabolic markers (in a standard microdialysis kit) and has favourable characteristics with a standardised measurement system that is routinely used for monitoring metabolites in the clinic. The technique is also effective when used at lower perfusate flow rates (<1 μl/minute), which is advantageous as the recovery of metabolic markers increases at low perfusate flow rates.

    Delarbeid
    1. Continuous assessment of concentrations of cytokines in experimental injuries of the extremity
    Åpne denne publikasjonen i ny fane eller vindu >>Continuous assessment of concentrations of cytokines in experimental injuries of the extremity
    Vise andre…
    2009 (engelsk)Inngår i: International Journal of Clinical and Experimental Medicine, ISSN 1940-5901, Vol. 2, nr 4, s. 354-362Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Background. Inflammation plays an important part in the healing process. Little is known about the extent local inflammatory trauma response interacts with the central circulation and inflammation produced by central organs. The aim of the present study was to examine whether high cut-off microdialysis catheters offer potential to in real time assess interstitial cytokines variations in conjunction to markers of metabolism distal to a blunt vascular contusion. Methods. In a standardised contusion trauma model, microdialysis catheters (high MW (100kDa)) were inserted in the gracilis muscle distal to the trauma for the local assessment of IL-6, IL-8, TNF-a, total protein and the metabolic mediators (glycerol, puruvate and lactate). The contra lateral uninjured leg served as control of the centrally mediated inflammation propagated to the extremities. Results. The trauma led to a significant and quantitatively large (8-10 fold) increase in inflammatory cytokines (IL6 and 8) as measured both in the injured and control legs. There was only a minor, and not significant increase in concentrations of cytokines in the injured leg compared to the control leg.. There were no signs of ischemia in either leg. Conclusion. The new finding in this study is that both central, and local, inflammatory responses as well as metabolic mediators may be assessed continuously in skeletal muscle tissue distal to a major injury in an animal model. The findings suggest that the large trauma elicits a generalised inflammatory response to trauma rather than propagating a local one distal to the trauma.

    sted, utgiver, år, opplag, sider
    e-Century Publishing Corporation, 2009
    Emneord
    Blunt trauma; Inflammation; Microcirculation; Microdialysis; Rat
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-57062 (URN)20057979 (PubMedID)
    Tilgjengelig fra: 2010-06-11 Laget: 2010-06-09 Sist oppdatert: 2010-12-28
    2. Urea clearance: a new method to register local changes in blood flow in rat skeletal muscle based on microdialysis
    Åpne denne publikasjonen i ny fane eller vindu >>Urea clearance: a new method to register local changes in blood flow in rat skeletal muscle based on microdialysis
    Vise andre…
    2010 (engelsk)Inngår i: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 30, nr 1, s. 57-63Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Pgreater thanIncreasing evidence suggests that local blood flow should be monitored during microdialysis (MD) as the recovery of analytes is affected by local blood flow. At present ethanol clearance is the standard technique for this purpose, but it is not functional at very low perfusion velocities. Here, we introduce a technique for MD whereby local tissue blood flow is recorded by the use of urea clearance (changes inflow/outflow concentration), in conjunction with measurements of tissue metabolism (glucose, lactate and puruvate). MD probes were inserted into the gracilis muscle of 15 rats and perfused with a medium containing urea (20 mmol l-1). Changes in muscle blood flow were made by addition of noradrenaline (5 mu g ml-1) to the perfusion medium at two perfusion velocities (0 center dot 6 and 0 center dot 4 mu l min-1). The clearance of urea from the perfusion medium was then calculated and examined in relation to the dose of noradrenaline and to the coexisting changes in extracellular metabolites. The results showed reproducible and dose-dependent changes in blood flow that were induced by noradrenaline. These were characterized by dose-dependent changes in the urea clearance as well as blood-flow-specific changes in the MD metabolic markers (reduction in glucose and increase in lactate). The sensitivity for blood flow changes as assessed by urea clearance (MD) was increased at 0 center dot 4 compared with the 0 center dot 6 mu l min-1 perfusion speed. The results indicate that inclusion of urea to the perfusion medium may be used to monitor changes in skeletal muscle blood flow at low perfusion velocities and in parallel assess metabolic variables with a high recovery (greater than 90%).

    Emneord
    extracellular fluid; glucose; lactate; metabolism; recovery
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-52899 (URN)10.1111/j.1475-097X.2009.00904.x (DOI)
    Tilgjengelig fra: 2010-01-13 Laget: 2010-01-12 Sist oppdatert: 2017-12-12
    3. Urea Clearance: A New Technique Based on Microdialysis to Assess Liver Blood Flow Studied in a Pig Model of Ischemia/Reperfusion
    Åpne denne publikasjonen i ny fane eller vindu >>Urea Clearance: A New Technique Based on Microdialysis to Assess Liver Blood Flow Studied in a Pig Model of Ischemia/Reperfusion
    Vise andre…
    2010 (engelsk)Inngår i: EUROPEAN SURGICAL RESEARCH, ISSN 0014-312X, Vol. 45, nr 2, s. 105-112Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Delayed detection of ischemia is one of the most feared postoperative complications. Early detection of impaired blood flow and close monitoring of the organ-specific metabolic status may therefore be critical for the surgical outcome. Urea clearance is a new technique for continuous monitoring of alterations in blood flow and metabolic markers with acceptable temporal characteristics. We compare this new microdialysis technique with the established microdialysis ethanol technique to assess hepatic blood flow. Six pigs were used in a liver ischemia/reperfusion injury model. Microdialysis catheters were placed in liver segment IV and all circulation was stopped for 80 min, followed by reperfusion for 220 min. Urea and ethanol clearance was calculated from the dialysate and correlated with metabolic changes. A laser Doppler probe was used as reference of restoration of blood flow. Both urea and ethanol clearance reproducibly depicted changes in liver blood flow in relation to metabolic changes and laser Doppler measurements. The two techniques highly correlated both overall and during the reperfusion phase (r = 0.8) and the changes were paralleled by altered perfusion as recorded by laser Doppler.

    sted, utgiver, år, opplag, sider
    S. Karger AG, 2010
    Emneord
    Liver perfusion, Lactate, Ethanol, Metabolism, Recovery
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-62299 (URN)10.1159/000319868 (DOI)000283851400006 ()
    Tilgjengelig fra: 2010-11-26 Laget: 2010-11-26 Sist oppdatert: 2012-03-20
    4. Assessment of blood flow changes in human skin by microdialysis urea clearance
    Åpne denne publikasjonen i ny fane eller vindu >>Assessment of blood flow changes in human skin by microdialysis urea clearance
    2011 (engelsk)Inngår i: Microcirculation, ISSN 1073-9688, E-ISSN 1549-8719, Vol. 18, nr 3, s. 198-204Artikkel, forskningsoversikt (Fagfellevurdert) Published
    Abstract [en]

    Objective: The aim of this study was to evaluate the urea clearance technique for the measurement of drug-induced blood flow changes in human skin, and compare it with two non-invasive techniques: polarization light spectroscopy and laser Doppler perfusion imaging.

    Methods: Fifteen microdialysis catheters were placed intracutaneously on the volar aspect of the forearms of healthy human subjects, and were perfused with nitroglycerine, noradrenaline, and again nitroglycerine, to induce local tissue hyperaemia, hypoperfusion, and hyperaemia, respectively.

    Results: Urea clearance, but not the other techniques, detected the changes in blood flow during all three periods of altered flow.  The last hyperaemic response was detected by all three methods.

    Conclusion: Urea clearance can be used as a relatively simple method to estimate blood flow changes during microdialysis of vasoactive substances, in particular when the tissue is preconditioned in order to enhance the contrast between baseline and the responses to the provocations. Our results support that, in the model described, urea clearance was superior to the optical methods as it detected both the increases and decrease in blood flow, and the returns to baseline between these periods.

    sted, utgiver, år, opplag, sider
    Wiley, 2011
    Emneord
    microcirculation; laser Doppler perfusion imaging; polarisation light spectroscopy; ischaemia; reperfusion; hypoperfusion; hyperaemia
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-63115 (URN)10.1111/j.1549-8719.2010.00077.x (DOI)000288759900004 ()
    Merknad
    The original title of article IV was "Assessment of blood flow changes in a new pharmacological model of microdosing in human skin by microdialysis urea clearance".Tilgjengelig fra: 2010-12-11 Laget: 2010-12-11 Sist oppdatert: 2018-01-12bibliografisk kontrollert
  • 7.
    Farnebo, Simon
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. VA Palo Alto Health Care System, Livermore, CA, USA.
    Farnebo, Lovisa
    Stanford University, CA, USA.
    Kim, Maxwell
    VA Palo Alto Health Care System, Livermore, CA, USA; Stanford University, CA, USA.
    Woon, Colin
    VA Palo Alto Health Care System, Livermore, CA, USA; Stanford University, CA, USA.
    Pham, Hung
    VA Palo Alto Health Care System, Livermore, CA, USA; Stanford University, CA, USA.
    Chang, James
    VA Palo Alto Health Care System, Livermore, CA, USA; Stanford University, CA, USA.
    Optimized Repopulation of Tendon Hydrogel: Synergistic Effects of Growth Factor Combinations and Adipose-Derived Stem Cells2017Inngår i: Hand (New York, N.Y.), ISSN 1558-9447, Vol. 12, nr 1, s. 68-77Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Tendon-derived extracellular matrix (ECM) hydrogel has been shown to augment tendon healing in vivo. We hypothesized that reseeding of the gel with adipose-derived stem cells (ASCs) could further assist repopulation of the gel and that combinations of growth factors (GFs) would improve the survival of these cells after reseeding. Methods: A tendon-specific ECM solution was supplemented with varying concentrations of basic fibroblast growth factor (bFGF), insulin-like growth factor-1 (IGF-1), and platelet-derived growth factor-BB (PDGF-BB). Gels were then seeded with ASCs transfected with a green fluorescent protein/luciferin construct. Cell proliferation was determined using the MTT assay and histology, and GF and ASC augmented gels were injected into the back of Sprague Dawley rats. Bioluminescence of seeded gels was continuously followed after reseeding, and cell counts were performed after the gels were explanted at 14 days. Results: Synergistic effects of the GFs were seen, and an optimal combination was determined to be 10 ng/mL bFGF, 100 ng/mL IGF-1, and 100 ng/mL PDGF-BB (2.8-fold increase; P amp;lt; .05). In vivo bioluminescence showed an improved initial survival of cells in gels supplemented with the optimal concentration of GF compared with the control group (10.6-fold increase at 8 days; P amp;lt; .05). Cell counts of explants showed a dramatic endogenous repopulation of gels supplemented by GF + ASCs compared with both gels with GF but no ASCs (7.6-fold increase) and gels with ASCs but no GF (1.6-fold increase). Conclusion: Synergistic effects of GFs can be used to improve cellular proliferation of ASCs seeded to a tendon ECM gel. Reseeding with ASCs stimulates endogenous repopulation of the gel in vivo and may be used to further augment tendon healing.

  • 8.
    Farnebo, Simon
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Gerber Ekblom, A.
    Karolinska Institute, Sweden.
    Hand surgery in Sweden2017Inngår i: Journal of Hand Surgery, European Volume, ISSN 1753-1934, E-ISSN 2043-6289, Vol. 42, nr 5, s. 537-539Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    n/a

  • 9.
    Farnebo, Simon
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Kirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Rekonstruktionscentrum, Hand- och plastikkirurgiska kliniken US.
    Karlander, Lars-Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Kirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Rekonstruktionscentrum, Hand- och plastikkirurgiska kliniken US.
    Steinwall, Ingrid
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Rekonstruktionscentrum, Hand- och plastikkirurgiska kliniken US.
    Sjögren, Florence
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Dermatologi och venerologi. Linköpings universitet, Hälsouniversitetet.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Rekonstruktionscentrum, Hand- och plastikkirurgiska kliniken US.
    Continuous assessment of concentrations of cytokines in experimental injuries of the extremity2009Inngår i: International Journal of Clinical and Experimental Medicine, ISSN 1940-5901, Vol. 2, nr 4, s. 354-362Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background. Inflammation plays an important part in the healing process. Little is known about the extent local inflammatory trauma response interacts with the central circulation and inflammation produced by central organs. The aim of the present study was to examine whether high cut-off microdialysis catheters offer potential to in real time assess interstitial cytokines variations in conjunction to markers of metabolism distal to a blunt vascular contusion. Methods. In a standardised contusion trauma model, microdialysis catheters (high MW (100kDa)) were inserted in the gracilis muscle distal to the trauma for the local assessment of IL-6, IL-8, TNF-a, total protein and the metabolic mediators (glycerol, puruvate and lactate). The contra lateral uninjured leg served as control of the centrally mediated inflammation propagated to the extremities. Results. The trauma led to a significant and quantitatively large (8-10 fold) increase in inflammatory cytokines (IL6 and 8) as measured both in the injured and control legs. There was only a minor, and not significant increase in concentrations of cytokines in the injured leg compared to the control leg.. There were no signs of ischemia in either leg. Conclusion. The new finding in this study is that both central, and local, inflammatory responses as well as metabolic mediators may be assessed continuously in skeletal muscle tissue distal to a major injury in an animal model. The findings suggest that the large trauma elicits a generalised inflammatory response to trauma rather than propagating a local one distal to the trauma.

  • 10.
    Farnebo, Simon
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Kirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Rekonstruktionscentrum, Hand- och plastikkirurgiska kliniken US.
    Samuelsson, A.
    Östergötlands Läns Landsting, Anestesi- och operationscentrum, Intensivvårdskliniken US.
    Henriksson, J.
    Karolinska Inst, Dept Physiol and Pharmacol, Stockholm, Sweden.
    Karlander, Lars-Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Kirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Rekonstruktionscentrum, Hand- och plastikkirurgiska kliniken US.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Brännskadevård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Urea clearance: a new method to register local changes in blood flow in rat skeletal muscle based on microdialysis2010Inngår i: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 30, nr 1, s. 57-63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pgreater thanIncreasing evidence suggests that local blood flow should be monitored during microdialysis (MD) as the recovery of analytes is affected by local blood flow. At present ethanol clearance is the standard technique for this purpose, but it is not functional at very low perfusion velocities. Here, we introduce a technique for MD whereby local tissue blood flow is recorded by the use of urea clearance (changes inflow/outflow concentration), in conjunction with measurements of tissue metabolism (glucose, lactate and puruvate). MD probes were inserted into the gracilis muscle of 15 rats and perfused with a medium containing urea (20 mmol l-1). Changes in muscle blood flow were made by addition of noradrenaline (5 mu g ml-1) to the perfusion medium at two perfusion velocities (0 center dot 6 and 0 center dot 4 mu l min-1). The clearance of urea from the perfusion medium was then calculated and examined in relation to the dose of noradrenaline and to the coexisting changes in extracellular metabolites. The results showed reproducible and dose-dependent changes in blood flow that were induced by noradrenaline. These were characterized by dose-dependent changes in the urea clearance as well as blood-flow-specific changes in the MD metabolic markers (reduction in glucose and increase in lactate). The sensitivity for blood flow changes as assessed by urea clearance (MD) was increased at 0 center dot 4 compared with the 0 center dot 6 mu l min-1 perfusion speed. The results indicate that inclusion of urea to the perfusion medium may be used to monitor changes in skeletal muscle blood flow at low perfusion velocities and in parallel assess metabolic variables with a high recovery (greater than 90%).

  • 11.
    Farnebo, Simon
    et al.
    Linköpings universitet, Institutionen för biomedicin och kirurgi, Avdelningen för kirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Rekonstruktionscentrum, Hand- och plastikkirurgiska kliniken US.
    Thorfinn, Johan
    Linköpings universitet, Institutionen för biomedicin och kirurgi, Avdelningen för kirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Rekonstruktionscentrum, Hand- och plastikkirurgiska kliniken US.
    Henricson, Joakim
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Hyperaemic changes in forearm skin perfusion and RBC concentration after increasing occlusion times2010Inngår i: MICROVASCULAR RESEARCH, ISSN 0026-2862, Vol. 80, nr 3, s. 412-416Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tissue occlusion and the hyperaemic response upon reperfusion can be used as a tool to assess microvascular function in various vascular diseases. Currently, laser Doppler flowmetry (LDF) is applied most often to measure hyperaemic responses. In this study, we have applied tissue viability imaging (TiVi) and LDF to measure the change in red blood cell concentration and perfusion in the skin after occlusions of the forearm with increasing duration. We have found that there is a strong correlation between the changes in perfusion and red blood cell (RBC) concentration during post-occlusive hyperaemia (perfusion: r = 0.80; RBC concentration: r = 0.94). This correlation increases with longer occlusion durations (1, 5 and 10 min). Furthermore, for both perfusion and RBC concentration, the maximum responses (perfusion: r(2) = 0.59; RBC concentration: r(2) = 0.78) and the recovery times (perfusion: r(2) = 0.62; RBC concentration: r(2) = 0.91) increase linearly with the duration of the occlusion. Maximum responses and recovery times were more reproducible for RBC concentration (as measured with TiVi) than for perfusion (as measured with LDF). These results show that perfusion and RBC concentration are related during post-occlusive hyperaemia and that TiVi can be used as a tool in the assessment of hyperaemic responses that has advantages in terms of reproducibility, sensitivity and ease of use.

  • 12.
    Farnebo, Simon
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Kirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Winbladh, Anders
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Zettersten, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Sandström, Per
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Kirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Kirurgiska kliniken i Östergötland med verksamhet i Linköping, Norrköping och Motala.
    Gullstrand, P
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Samuelsson, Anders
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Intensivvårdskliniken US.
    Theodorsson, Elvar
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Klinisk kemi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Laboratoriemedicinskt centrum, Klinisk kemi.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Brännskadevård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Urea Clearance: A New Technique Based on Microdialysis to Assess Liver Blood Flow Studied in a Pig Model of Ischemia/Reperfusion2010Inngår i: EUROPEAN SURGICAL RESEARCH, ISSN 0014-312X, Vol. 45, nr 2, s. 105-112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Delayed detection of ischemia is one of the most feared postoperative complications. Early detection of impaired blood flow and close monitoring of the organ-specific metabolic status may therefore be critical for the surgical outcome. Urea clearance is a new technique for continuous monitoring of alterations in blood flow and metabolic markers with acceptable temporal characteristics. We compare this new microdialysis technique with the established microdialysis ethanol technique to assess hepatic blood flow. Six pigs were used in a liver ischemia/reperfusion injury model. Microdialysis catheters were placed in liver segment IV and all circulation was stopped for 80 min, followed by reperfusion for 220 min. Urea and ethanol clearance was calculated from the dialysate and correlated with metabolic changes. A laser Doppler probe was used as reference of restoration of blood flow. Both urea and ethanol clearance reproducibly depicted changes in liver blood flow in relation to metabolic changes and laser Doppler measurements. The two techniques highly correlated both overall and during the reperfusion phase (r = 0.8) and the changes were paralleled by altered perfusion as recorded by laser Doppler.

  • 13.
    Farnebo, Simon
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Hand och plastikkirurgi. Linköpings universitet, Hälsouniversitetet.
    Zettersten, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Samuelsson, Anders
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Intensivvårdskliniken US. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Brännskadevård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Assessment of blood flow changes in human skin by microdialysis urea clearance2011Inngår i: Microcirculation, ISSN 1073-9688, E-ISSN 1549-8719, Vol. 18, nr 3, s. 198-204Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Objective: The aim of this study was to evaluate the urea clearance technique for the measurement of drug-induced blood flow changes in human skin, and compare it with two non-invasive techniques: polarization light spectroscopy and laser Doppler perfusion imaging.

    Methods: Fifteen microdialysis catheters were placed intracutaneously on the volar aspect of the forearms of healthy human subjects, and were perfused with nitroglycerine, noradrenaline, and again nitroglycerine, to induce local tissue hyperaemia, hypoperfusion, and hyperaemia, respectively.

    Results: Urea clearance, but not the other techniques, detected the changes in blood flow during all three periods of altered flow.  The last hyperaemic response was detected by all three methods.

    Conclusion: Urea clearance can be used as a relatively simple method to estimate blood flow changes during microdialysis of vasoactive substances, in particular when the tissue is preconditioned in order to enhance the contrast between baseline and the responses to the provocations. Our results support that, in the model described, urea clearance was superior to the optical methods as it detected both the increases and decrease in blood flow, and the returns to baseline between these periods.

  • 14.
    Frueh, Florian S.
    et al.
    Univ Hosp Zurich, Switzerland.
    Megerle, Kai
    Tech Univ Munich, Germany.
    Luria, Shai
    Hadassah Hebrew Univ Med Ctr, Israel.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Research activity among European hand surgery residents2019Inngår i: Journal of Hand Surgery, European Volume, ISSN 1753-1934, E-ISSN 2043-6289, Vol. 44, nr 7, s. 764-765Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    n/a

  • 15.
    Högstedt, Alexandra
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Iredahl, Fredrik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Primärvårdscentrum, Vårdcentralen Åby.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Effect of N-G-monomethyl l-arginine on microvascular blood flow and glucose metabolism after an oral glucose load2019Inngår i: Microcirculation, ISSN 1073-9688, E-ISSN 1549-8719, artikkel-id e12597Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective The aim of this study was to investigate whether the effects on local blood flow and metabolic changes observed in the skin after an endogenous systemic increase in insulin are mediated by the endothelial nitric oxide pathway, by administering the nitric oxide synthase inhibitor N-G-monomethyl l-arginine using microdialysis. Methods Microdialysis catheters, perfused with N-G-monomethyl l-arginine and with a control solution, were inserted intracutaneously in 12 human subjects, who received an oral glucose load to induce a systemic hyperinsulinemia. During microdialysis, the local blood flow was measured by urea clearance and by laser speckle contrast imaging, and glucose metabolites were measured. Results After oral glucose intake, microvascular blood flow and glucose metabolism were both significantly suppressed in the N-G-monomethyl l-arginine catheter compared to the control catheter (urea clearance: P amp;lt; .006, glucose dialysate concentration: P amp;lt; .035). No significant effect of N-G-monomethyl l-arginine on microvascular blood flow was observed with laser speckle contrast imaging (P = .81). Conclusion Local delivery of N-G-monomethyl l-arginine to the skin by microdialysis reduces microvascular blood flow and glucose delivery in the skin after oral glucose intake, presumably by decreasing local insulin-mediated vasodilation.

    Fulltekst tilgjengelig fra 2020-10-19 13:28
  • 16.
    Iredahl, Fredrik
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Högstedt, Alexandra
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Henricson, Joakim
    Linköpings universitet, Medicinska fakulteten. Region Östergötland, Hjärt- och Medicincentrum, Hudkliniken i Östergötland. Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Skin glucose metabolism and microvascular blood flow during local insulin delivery and after an oral glucose load2016Inngår i: Microcirculation, ISSN 1073-9688, E-ISSN 1549-8719, Vol. 23, nr 7, s. 597-605Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVE: Insulin causes capillary recruitment in muscle and adipose tissue, but the metabolic and microvascular effects of insulin in the skin have not been studied in detail. The aim of this study was to measure glucose metabolism and microvascular blood flow in the skin during local insulin delivery and after an oral glucose load.

    METHODS: Microdialysis catheters were inserted intracutanously in human subjects. In eight subjects two microdialysis catheters were inserted, one perfused with insulin and one with control solution. First the local effects of insulin was studied, followed by a systemic provocation by an oral glucose load. Additionally, as control experiment, six subjects did not recieve local delivery of insulin or the oral glucose load. During microdialysis the local blood flow was measured by urea clearance and by laser speckle contrast imaging (LSCI).

    RESULTS: Within 15 minutes of local insulin delivery, microvascular blood flow in the skin increased (urea clearance: P=.047, LSCI: P=.002) paralleled by increases in pyruvate (P=.01) and lactate (P=.04), indicating an increase in glucose uptake. An oral glucose load increased urea clearance from the catheters, indicating an increase in skin perfusion, although no perfusion changes were detected with LSCI. The concentration of glucose, pyruvate and lactate increased in the skin after the oral glucose load.

    CONCLUSION: Insulin has metabolic and vasodilatory effects in the skin both when given locally and after systemic delivery through an oral glucose load.

  • 17.
    Iredahl, Fredrik
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Löfberg, Andreas
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för neuro- och inflammationsvetenskap. Linköpings universitet, Medicinska fakulteten.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Linköpings universitet, Medicinska fakulteten.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Non-Invasive Measurement of Skin Microvascular Response during Pharmacological and Physiological Provocations2015Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 8, s. 1-15, artikkel-id e0133760Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Introduction Microvascular changes in the skin due to pharmacological and physiological provocations can be used as a marker for vascular function. While laser Doppler flowmetry (LDF) has been used extensively for measurement of skin microvascular responses, Laser Speckle Contrast Imaging (LSCI) and Tissue Viability Imaging (TiVi) are novel imaging techniques. TiVi measures red blood cell concentration, while LDF and LSCI measure perfusion. Therefore, the aim of this study was to compare responses to provocations in the skin using these different techniques. Method Changes in skin microcirculation were measured in healthy subjects during (1) iontophoresis of sodium nitroprusside (SNP) and noradrenaline (NA), (2) local heating and (3) post-occlusive reactive hyperemia (PORH) using LDF, LSCI and TiVi. Results Iontophoresis of SNP increased perfusion (LSCI: baseline 40.9 +/- 6.2 PU; 10-min 100 +/- 25 PU; pless than0.001) and RBC concentration (TiVi: baseline 119 +/- 18; 10-min 150 +/- 41 AU; p = 0.011). No change in perfusion (LSCI) was observed after iontophoresis of NA (baseline 38.0 +/- 4.4 PU; 10-min 38.9 +/- 5.0 PU; p = 0.64), while RBC concentration decreased (TiVi: baseline 59.6 +/- 11.8 AU; 10-min 54.4 +/- 13.3 AU; p = 0.021). Local heating increased perfusion (LDF: baseline 8.8 +/- 3.6 PU; max 112 +/- 55 PU; pless than0.001, LSCI: baseline 50.8 +/- 8.0 PU; max 151 +/- 22 PU; pless than0.001) and RBC concentration (TiVi: baseline 49.2 +/- 32.9 AU; max 99.3 +/- 28.3 AU; pless than0.001). After 5 minutes of forearm occlusion with prior exsanguination, a decrease was seen in perfusion (LDF: p = 0.027; LSCI: pless than0.001) and in RBC concentration (p = 0.045). Only LSCI showed a significant decrease in perfusion after 5 minutes of occlusion without prior exsanguination (pless than0.001). Coefficients of variation were lower for LSCI and TiVi compared to LDF for most responses. Conclusion LSCI is more sensitive than TiVi for measuring microvascular changes during SNP-induced vasodilatation and forearm occlusion. TiVi is more sensitive to noradrenaline-induced vasoconstriction. LSCI and TiVi show lower inter-subject variability than LDF. These findings are important to consider when choosing measurement techniques for studying skin microvascular responses.

  • 18.
    Iredahl, Fredrik
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Sadda, Veeranjaneyulu
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Ward, Liam
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Hackethal, Johannes
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. University of Appl Science, Austria.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Modeling Perfusion Dynamics in the Skin During Iontophoresis of Vasoactive Drugs Using Single-Pulse and Multiple-Pulse Protocols2015Inngår i: Microcirculation, ISSN 1073-9688, E-ISSN 1549-8719, Vol. 22, nr 6, s. 446-453Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: After iontophoresis of vasoactive drugs into the skin, a decrease in perfusion is commonly observed. We delivered vasoactive drugs by iontophoresis using different delivery protocols to study how these affect this decrease in perfusion as measured using LDF. Methods: We measured skin perfusion during iontophoresis of (ACh), MCh, andNAusing a single pulse or separate pulses at different skin sites, and during repeated delivery of ACh at the same site. Results: Perfusion half-life was 6.1 (5.6-6.6) minutes for ACh and 41 (29-69) minutes for MCh (p less than 0.001). The maximum response with multiple pulses of ACh iontophoresis was lower than with a single pulse, 30 (22-37) PU vs. 43 (36-50) PU, p less than 0.001. Vasoconstriction to NA was more rapid with a single pulse than with multiple pulses. The perfusion half-life of ACh decreased with repeated delivery of ACh at the same site-first 16 (14-18), second 5.9 (5.1-6-9) and third 3.2 (2.9-3.5) minutes, p less than 0.001. Conclusions: The drug delivery protocol affects microvascular responses to iontophoresis, possibly as a result of differences in the dynamics of local drug concentrations. Perfusion half-life may be used as a measure to quantify the rate of perfusion recovery after iontophoresis of vasoactive drugs.

  • 19.
    Iredahl, Fredrik
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Hälsouniversitetet.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Hälsouniversitetet.
    Sarker, Saikat
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och intensivvårdskliniken US.
    The Microvascular Response to Transdermal Iontophoresis of Insulin is Mediated by Nitric Oxide2013Inngår i: Microcirculation, ISSN 1073-9688, E-ISSN 1549-8719, Vol. 20, nr 8, s. 717-723Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    ObjectiveInsulin has direct effects on blood flow in various tissues, most likely due to endothelial NO production. We investigated whether insulin delivered to the skin by iontophoresis increases microvascular perfusion and whether this effect is partly or completely mediated by the release of NO. MethodsIn healthy subjects, regular insulin and monomeric insulin were delivered to the skin by cathodal iontophoresis. The skin was pretreated either with L-NAME or control solution (PBS) using anodal iontophoresis. Microvascular responses were measured using laser Doppler flowmetry. ResultsA dose-dependent increase in perfusion was observed during iontophoresis of regular and monomeric insulin. The maximum perfusion was significantly elevated compared with control after PBS (regular insulin 53.6 (12.7-95.6) PU vs. 4.2 (3.4-4.8) PU, p = 0.002; monomeric insulin 32.6 (8.9-92.6) PU vs. 5.9 (3.4-56.0) PU, p = 0.03). The microvascular response to insulin was abolished after L-NAME (regular insulin: 25.6 (11.6-54.4) PU vs. control: 4.7 (2.9-11.5) PU, p = 0.15; monomeric insulin 10.9 (5.4-56.8) PU vs. control: 4.7 (2.9-11.5) PU, p = 0.22). ConclusionsThe main finding is that iontophoresis of insulin induces a dose-dependent vasodilation in the skin, which could be suppressed after pretreatment with a NO synthase inhibitor. This suggests that vasodilation in the skin after iontophoresis of insulin is mediated by the NO pathway.

  • 20.
    Mirdell, Robin
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Närsjukvården i västra Östergötland.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Medicinsk strålningsfysik. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper.
    Accuracy of laser speckle contrast imaging in the assessment of pediatric scald wounds2018Inngår i: Burns, ISSN 0305-4179, E-ISSN 1879-1409, Vol. 44, nr 1, s. 90-98Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Changes in microvascular perfusion in scalds in children during the first four days, measured with laser speckle contrast imaging (LSCI), are related to the time to healing and need for surgical intervention. The aim of this study was to determine the accuracy (sensitivity and specificity) of LSCI on different days after injury in the prediction of healing outcome and if the accuracy can be improved by combining an early and a late measurement. Also, the accuracy of LSCI was compared with that of clinical assessment. Methods: Perfusion was measured between 0-24h and between 72-96h using LSCI in 45 children with scalds. On the same occasions, burn surgeons assessed the burns as healing amp;lt; 14days or healing amp;gt; 14days/surgery. Receiver operating characteristic (ROC) curves were constructed for the early and late measurement and for the double measurement (DM) using two different methods. Results: Sensitivity and specificity were 92.3% (95% CI: 64.0-99.8%) and 78.3% (95% CI: 69.985.3%) between 0-24h, 100% (95% CI: 84.6-100%) and 90.4% (95% CI: 83.8-94.9%) between 72-96h, and was 100% (95% CI: 59.0-100%) and 100% (95% CI: 95.1-100%) when combining the two measurements into a modified perfusion trend. Clinical assessment had an accuracy of 67%, Cohens k=0.23. Conclusion: The perfusion in scalds between 72-96h after injury, as measured using LSCI, is highly predictive of healing outcome in scalds when measured. The predictive value can be further improved by incorporating an early perfusion measurement within 24h after injury. (C) 2017 Elsevier Ltd and ISBI. All rights reserved.

  • 21.
    Mirdell, Robin
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Anestesi- och intensivvårdskliniken US (ANOPIVA).
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Interobserver reliability of laser speckle contrast imaging in the assessment of burns2019Inngår i: Burns, ISSN 0305-4179, E-ISSN 1879-1409, Vol. 45, nr 6, s. 1325-1335Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objectives: Laser speckle contrast imaging (LSCI) is an emerging technique for the assessment of burns in humans and interobserver differences have not been studied. The aim of this study was to compare assessments of perfusion images by different professional groups regarding (i) perfusion values and (ii) burn depth assessment. Methods: Twelve observers without LSCI experience were included. The observers were evenly recruited from three professional groups: plastic surgeons with experience in assessing burns, nurses with experience in treating burns, and junior doctors with limited experience of burns. Ten cases were included. Each case consisted of one digital photo of the burn with a pre-marked region of interest (ROI) and two unmarked perfusion images of the same area. The first and the second perfusion image was from 24h and 72-96h after injury, respectively. The perfusion values from both perfusion images were used to generate a LSCI recommendation based on the perfusion trend (the derivative between the two perfusion values). As a last step, each observer was asked to estimate the burn depth using their clinical experience and all available information. Intraclass correlation (ICC) was calculated between the different professional groups and among all observers. Results: Perfusion values and perfusion trends between all observers had an ICC of 0.96 (95% CI 0.91-0.99). Burn depth assessment by all observers yielded an ICC of 0.53 (95% CI: 0.31-0.80) and an accuracy of 0.53 (weighted kappa). LSCI recommendations generated by all observers had an ICC of 0.95 (95% CI: 0.90-0.99). Conclusion: Observers can reliably identify the same ROI, which results in observer-independent perfusion measurements, irrespective of burn experience. Extensive burn experience did not further improve burn depth assessment. The LSCI recommendation was more accurate in all professional groups. Introducing LSCI measurements would be likely improve early assessment of burns. (C) 2019 Elsevier Ltd and ISBI. All rights reserved.

    Fulltekst tilgjengelig fra 2020-06-21 15:29
  • 22.
    Mirdell, Robin
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Medicinska fakulteten.
    Iredahl, Fredrik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Linköpings universitet, Medicinska fakulteten.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Microvascular blood flow in scalds in children and its relation to duration of wound healing: A study using laser speckle contrast imaging2016Inngår i: Burns, ISSN 0305-4179, E-ISSN 1879-1409, Vol. 42, nr 3, s. 648-654Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Microvascular perfusion changes in scalds in children during the first weeks after injury is related to the outcome of healing, and measurements of perfusion, based on laser Doppler imaging, have been used successfully to predict the need for excision and grafting. However, the day-to-day changes in perfusion during the first weeks after injury have not to our knowledge been studied in detail. The aim of this study, based on a conservative treatment model where excision and grafting decisions were delayed to day 14 after injury, was to measure changes in perfusion in scalds using laser speckle contrast imaging (LSCI) during the first three weeks after injury. Methods: We measured perfusion with LSCI in 34 patients at regular intervals between 6 h after injury until complete reepithelialization or surgery. Duration of healing was defined as the time to complete reepithelialization. Results: Less perfusion, between 6 and 96 h after injury, was associated with longer duration of healing with the strongest association occurring between 72 and 96 h. Burns that healed within 14 days had relatively high initial perfusion, followed by a peak and subsequent slow decrease. Both the maximum perfusion and the time-to-peak were dependent on the severity of the burn. Burns that needed excision and grafting had less initial perfusion and a gradual reduction over time. Conclusion: The perfusion in scalds in children shows characteristic patterns during the first weeks after injury depending on the duration of wound healing, the greatest difference between wounds of different severity being on the 4th day. Perfusion should therefore preferably be measured on the fourth day if it is to be used in the assessment of burn depth. (c) 2015 Elsevier Ltd and ISBI. All rights reserved.

  • 23.
    Mirdell, Robin
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Lemstra-Idsardi, Aukje Nienke
    University of Twente, Enschede, Netherlands.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Medicinsk strålningsfysik. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper.
    Data on microcirculatory perfusion dips in the resting nail bed2018Inngår i: Data in Brief, E-ISSN 2352-3409, Vol. 21, s. 1232-1235Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article contains the raw data from the article entitled: "The presence of synchronized perfusion dips in the microcirculation of the resting nail bed" Mirdell et al. (in press). A laser speckle contrast imager (LSCI) was used to make a total of 21 recordings of the perfusion in the resting nail bed of 10 healthy test subjects. The first 10 recordings were acquired after 5?min of acclimatization. An additional 10 recordings were acquired in the same test subjects, after 20?min of acclimatization. In the last recording, a digital nerve block was applied to the left dig III. The data show the presence of highly irregular perfusion variations, a phenomenon we like to call perfusion dips. The data also show how the perfusion dips can be abolished through a digital nerve block. An algorithm for the quantification of the perfusion dips is included in the data.

  • 24.
    Mirdell, Robin
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Lemstra-Idsardi, Aukje Nienke
    Univ Twente, Netherlands.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    The presence of synchronized perfusion dips in the microcirculation of the resting nail bed2019Inngår i: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 121, s. 71-81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objectives: Laser speckle contrast imaging (LSCI) has seen limited use in the study of perfusion dynamics such as vasomotion. The aim of this study was to investigate the effects of a prolonged seated position on perfusion dynamics in the nail bed using LSCI. Methods: Perfusion was recorded in digits II to IV bilaterally for 20 min during two separate sessions in ten healthy volunteers. The acclimatization period was 5 min for the 1st session and 20 min for the 2nd. Perfusion variability and the presence of recurring perfusion dips were analyzed. A digital nerve block was done to verify suspected nervous origin of phenomenon. Results: Synchronized phases of vasoconstriction were observed in all subjects with perfusion dips in all digits bilaterally and simultaneously. Application of a digital nerve block abolished perfusion dips. The frequency of this phenomenon increased by 25.0% (95% CI: 1.6 to 49.2%) in the left-hand digits after a prolonged seated position. Perfusion variability increased by 11.6% (95% CI: 2.6 to 20.3%) in the digits of the left hand. Perfusion changes in right-hand digits did not significantly increase. During the 1st session, temperature increased by 2.7 degrees C (1.1 to 4.2) while it decreased by 1.3 degrees C (0.2 to 2.4) during the 2nd session. Conclusion: The observed perfusion dips are of a centrally mediated nervous origin but are also affected by local factors. They are affected by seating duration and differ between left and right hands, likely because of local micro perfusion dips. This phenomenon seems related to digital thermoregulation.

  • 25.
    Moloney, Maria
    et al.
    Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Adolfsson, Lars
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    20-Year outcome of TFCC repairs2018Inngår i: Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery, ISSN 2000-656X, E-ISSN 2000-6764, Vol. 52, nr 3, s. 193-197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aims of this study were to investigate the functional result and rate of osteoarthritis 15-25 years after a TFCC-repair. Forty-seven patients completed the questionnaire Patient Rated Wrist Evaluation (PRWE), and 43 had new X-rays. Fifty-seven percent had a simultaneous arthroscopy. Sixteen patients had later additional surgery to the wrist, of these eight had a reoperation of the TFCC-injury due to recurrent instability. Radiographs showed that 17.5% had developed radiocarpal osteoarthritis and 34% osteoarthritis in the distal radioulnar joint. The median PRWE result was 22.5. Patients with radiocarpal osteoarthritis and patients who had additional surgery had significantly worse scores. Patients who had undergone arthroscopy significantly less often had developed radiocarpal osteoarthritis. The result is acceptable but not impressive and efforts should be made to diagnose these injuries early and also diagnose associated injuries, advisably by arthroscopy.

  • 26.
    Moloney, Maria
    et al.
    Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Adolfsson, Lars
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Ortopedkliniken i Linköping.
    Incidence of distal ulna fractures in a Swedish county: 74/100,000 person-years, most of them treated non-operatively2019Inngår i: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background and purpose - Fractures of the distal ulna can occur in isolation or in conjunction with a distal radius fracture. They may result in incongruence and instability of the distal radioulnar joint. We investigated the incidence of distal ulna fractures, whether any fracture types were more common, and the methods of treatment used. Patients and methods - Data were collected from patients 18 years or older, treated for a fracture of the distal ulna in ostergotland, Sweden, during 2010-2012. Patients were identified in the patient registry. The fractures were classified according to the AO comprehensive classification of fractures. Results - The incidence of distal ulna fractures was 74/100,000 person-years. The most common fracture type was that of the ulnar styloid Q1 (79%), followed by the ulnar neck Q2 (11%). Rarest was ulna head fracture, type Q4 (1%). Incidental findings were a mean age of 63 years (SD 18), a concomitant distal radius fracture in 92% of the patients and that 79% were caused by falling from standing height. Internal fixation was performed in 30% of the Q2-Q6 fractures. This indicates that most were considered stable without internal fixation or stable after fixation of a concomitant radius fracture. Interpretation - Our results show that fractures of the distal ulna are not very common, and some fracture types are even rare. There seem to be no consensus on treatment.

  • 27.
    Nilsson, Klara
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Medicinska fakulteten.
    Hallberg, Peter
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Maskinkonstruktion. Linköpings universitet, Tekniska fakulteten.
    Droog Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Medicinsk strålningsfysik.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    A Novel Technique to Assess Distal Radioulnar Joint Stability Using Increasing Torque2019Inngår i: Journal of wrist surgery, ISSN 2163-3916, E-ISSN 2163-3924, Vol. 8, nr 4, s. 327-334Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background Previous studies on computed tomography (CT) in patients with a suspected triangular fibrocartilage complex (TFCC) injury have not been successful in assessing distal radioulnar joint (DRUJ) laxity. The aim of this study was to develop a novel servomotor-driven device for the assessment of DRUJ by applying increasing torque to the DRUJ in pronation and supination. Methods A custom-built device was designed to function during four-dimensional (4D) CT of the wrist. A torque meter, positioned between the incoming hand holder, and a direct current (DC) servomotor were used for angular positioning and for applying rotational force to the patients arm. A total of 110 healthy participants were recruited to gather reference values for the range of motion (ROM), maximum torque in neutral and supinated/pronated position, and the ability to withstand an increasing, device-generated torque in these positions. The device was also used during 4D DRUJ CT in five patients with suspected TFCC injuries. Results A gender- and age-relevant reference chart for ROM and torque was created. Men showed a tendency (ns) toward having a larger ROM and increasing strength with increasing age, whereas women showed the opposite. Also, the dominant hand showed a tendency toward having a larger ROM and being stronger than the nondominant hand (ns). A smaller cohort of patients ( n = 5) with suspected TFCC injuries showed a significantly decreased ability to withstand increasing torque in both supination (2.1 +/- 0.3 vs. 3.1 +/- 0.2 s; p amp;lt; 0.005) and pronation (2.3 +/- 0.5 vs. 3.1 +/- 0.4 s; p amp;lt; 0.0005) and also showed a clear laxity on real-time 4D CT image sequences. Decreased strength at all positions was also found (average 74% decrease compared to noninjured side). Conclusion Reference values for torque strength and ability to withstand increasing torque can be used clinically in the assessment of patients with symptoms that could represent ligamentous injuries to the TFCC. The ability to use the device during CT enables radiographic evaluation of instability during increasing torque.

  • 28.
    Samuelsson, Anders
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Anestesi- och operationscentrum.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Kirurgi. Linköpings universitet, Hälsouniversitetet.
    Magnusson, Beatrice
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Dermatologi och venerologi. Linköpings universitet, Hälsouniversitetet.
    Anderson, Chris
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Dermatologi och venerologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Medicincentrum, Hudkliniken i Östergötland.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Brännskadevård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Rekonstruktionscentrum, Hand- och plastikkirurgiska kliniken US.
    Implications for critical care of a new in vivo human vascular microdosing technique for giving noradrenaline and nitroglycerine by microdialysisManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Introduction: Skin has a large dynamic capacity for alterations in blood flow, and is therefore often used for recruitment of blood during states of hypoperfusion. Little is known, however, about the metabolic consequences seen in skin secondary to hyporperfusion, particularly when the effects of vasoactive drugs are involved. The aims of this study were: to develop an in vivo, human microdosing model based on microdialysis in skin; and to investigate the effects on blood flow and metabolism of administering noradrenaline and nitroglycerine locally.

    Method: Nine healthy volunteers each had two or three microdialysis catheters placed intradermally in the volar surface of the lower arm. After a stabilisation period, the catheters were perfused with buffers containing noradrenaline 0.5 or 5 μg/ml for 60 minutes, and after a second period of equilibrium of 60 minutes, all catheters were perfused with buffer containing nitroglycerine (0.5mg/ml). Changes in the blood flow in the skin were measured by laser Doppler imaging urea and ethanol clearance. Simultaneous changes in tissue glucose, lactate, and pyruvate concentrations were recorded.

    Results: Perfusing skin with noradrenaline and nitroglycerine induced appreciable changes in all variables studied, depending on time and dose. The changes in glucose and lactate concentrations correlated with the change in blood flow assessed by either laser Doppler imaging or urea clearance. The changes in glucose and lactate that were induced by vasoconstriction (noradrenaline) continued until vasodilatation was induced by nitroglycerine.

    Conclusion: Noradrenaline given by microdialysis in healthy volunteers induced reproducible and dose-dependent hypoperfusion and ischaemia with simultaneous metabolic consequences. Among these, we particularly note that: tissue glucose concentrations responded rapidly to hypoperfusion but remained considerably higher than zero, which suggests an energy-dependent deficiency in cellular uptake; and vasoconstriction remained after cessation of the noradrenaline perfusion, implicating vasospasm and a lack of autoregulatory (recovery) capacity in skin. These findings are particularly interesting from the critical care perspective, where noradrenaline is used extensively for circulatory support. The metabolic consequences may be underestimated and our results suggest that further investigations are warranted.

  • 29.
    Samuelsson, Anders
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Anestesiologi med intensivvård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Intensivvårdskliniken US.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Kirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Magnusson, Beatrice
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Anderson, Chris
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Dermatologi och venerologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Hudkliniken i Östergötland.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Zettersten, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Brännskadevård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Implications for burn shock resuscitation of a new in vivo human vascular microdosing technique (microdialysis) for dermal administration of noradrenaline2012Inngår i: Burns, ISSN 0305-4179, E-ISSN 1879-1409, Vol. 38, nr 7, s. 975-983Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Introduction: Skin has a large dynamic capacity for alterations in blood flow, and is therefore often used for recruitment of blood during states of hypoperfusion such as during burn shock resuscitation. However, little is known about the blood flow and metabolic consequences seen in the dermis secondary to the use vasoactive drugs (i.e. noradrenaline) for circulatory support. The aims of this study were therefore: to develop an in vivo, human microdosing model based on dermal microdialysis; and in this model to investigate effects on blood flow and metabolism by local application of noradrenaline and nitroglycerin by the microdialysis system simulating drug induced circulatory support. less thanbrgreater than less thanbrgreater thanMethod: Nine healthy volunteers had microdialysis catheters placed intradermally in the volar surface of the lower arm. The catheters were perfused with noradrenaline 3 or 30 mmol/L and after an equilibrium period all catheters were perfused with nitroglycerine (2.2 mmol/L). Dermal blood flow was measured by the urea clearance technique and by laser Doppler imaging. Simultaneously changes in dermal glucose, lactate, and pyruvate concentrations were recorded. less thanbrgreater than less thanbrgreater thanResults: Noradrenaline and nitroglycerine delivered to the dermis by the microdialysis probes induced large time- and dose-dependent changes in all variables. We particularly noted that tissue glucose concentrations responded rapidly to hypoperfusion but remained higher than zero. Furthermore, vasoconstriction remained after the noradrenaline administration implicating vasospasm and an attenuated dermal autoregulatory capacity. The changes in glucose and lactate by vasoconstriction (noradrenaline) remained until vasodilatation was actively induced by nitroglycerine. less thanbrgreater than less thanbrgreater thanConclusion: These findings, i.e., compromised dermal blood flow and metabolism are particularly interesting from the burn shock resuscitation perspective where noradrenaline is commonly used for circulatory support. The importance and clinical value of the results obtained in this in vivo dermal model in healthy volunteers needs to be further explored in burn-injured patients.

  • 30.
    Tesselaar, Erik
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Brännskadevård. Linköpings universitet, Hälsouniversitetet.
    Bergkvist, Max
    Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Brännskadevård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Kirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Polarized Light Spectroscopy for Measurement of the Microvascular Response to Local Heating at Multiple Skin Sites2012Inngår i: Microcirculation, ISSN 1073-9688, E-ISSN 1549-8719, Vol. 19, nr 8, s. 705-713Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: To evaluate whether TiVi, a technique based on polarized light, could measure the change in RBC concentration during local heating in healthy volunteers. Methods: Using a custom-made transparent heater, forearm skin was heated to 42 degrees C for 40 minutes while the change in RBC concentration was measured with TiVi. The perfusion response during local heating was measured at the same time with Laser Doppler flowmetry. Results: Mean RBC concentration increased (91 +/- 34 vs. 51 +/- 34 A.U. at baseline, p less than 0.001). The spatial heterogeneity of the RBC concentration in the measured skin areas was 26 +/- 6.4% at baseline, and 23 +/- 4.6% after 40 minutes of heating. The mean RBC concentrations in two skin sites were highly correlated (0.98 at baseline and 0.96 after 40 minutes of heating). The change in RBC concentration was less than the change in perfusion, measured with LDF. Unlike with LDF, a neurally mediated peak was not observed with TiVi in most of the test subjects. Conclusions: TiVi is a valuable technique for measuring the microvascular response to local heating in the skin, and offers a high reproducibility for simultaneous measurements at different skin sites, provided carefully controlled experiments are ensured.

  • 31.
    Tesselaar, Erik
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Brännskadevård. Linköpings universitet, Hälsouniversitetet.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Kirurgi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Sjöberg, Folke
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Brännskadevård. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Östergötlands Läns Landsting, Sinnescentrum, Anestesi- och operationkliniken US.
    Measurement of red blood cell concentration in skin during vascular provocations using polarization light spectroscopy imaging in JOURNAL OF VASCULAR RESEARCH, vol 48, issue , pp 164-1642011Inngår i: JOURNAL OF VASCULAR RESEARCH, Karger , 2011, Vol. 48, s. 164-164Konferansepaper (Fagfellevurdert)
    Abstract [en]

    n/a

  • 32.
    Tesselaar, Erik
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Nezirevic Dernroth, Dzeneta
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för mikrobiologi och molekylär medicin. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Klinisk kemi.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Acute effects of coffee on skin blood flow and microvascular function2017Inngår i: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 114, s. 58-64Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective

    Studies on the acute effects of coffee on the microcirculation have shown contradicting results. This study aimed to investigate if intake of caffeine-containing coffee changes blood flow and microvascular reactivity in the skin.

    Methods

    We measured acute changes in cutaneous vascular conductance (CVC) in the forearm and the tip of the finger, the microvascular response to transdermaliontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP) and post-occlusive reactive hyperemia (PORH) in the skin, after intake of caffeinated or decaffeinated coffee.

    Results

    Vasodilatation during iontophoresis of ACh was significantly stronger after intake of caffeinated coffee compared to after intake of decaffeinated coffee (1.26 ± 0.20 PU/mm Hg vs. 1.13 ± 0.38 PU/mm Hg, P < 0.001). Forearm CVC before and after PORH were not affected by caffeinated and decaffeinated coffee. After intake of caffeinated coffee, a more pronounced decrease in CVC in the fingertip was observed compared to after intake of decaffeinated coffee (− 1.36 PU/mm Hg vs. − 0.52 PU/mm Hg, P = 0.002).

    Conclusions

    Caffeine, as ingested by drinking caffeinated coffee acutely improves endothelium-dependent microvascular responses in the forearm skin, while endothelium-independent responses to PORH and SNP iontophoresis are not affected. Blood flow in the fingertip decreases markedly during the first hour after drinking caffeinated coffee compared to decaffeinated coffee.

  • 33.
    Wikner, Jacob
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniska Kretsar och System. Linköpings universitet, Tekniska fakulteten.
    Zötterman, Johan
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Jalili, Armin
    Linköpings universitet, Institutionen för systemteknik, Elektroniska Kretsar och System. Linköpings universitet, Tekniska fakulteten.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Aiming for the cloud - a study of implanted battery-free temperature sensors using NFC2016Inngår i: 2016 INTERNATIONAL SYMPOSIUM ON INTEGRATED CIRCUITS (ISIC), IEEE , 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we present results based on measurements of implantable devices which can be powered externally and communicated with using the near-field communication (NFC) infrastructure. NFC allows us to not have a dedicated gateway and intra-body communication to bridge the data from sensors to phone. In our trials, we have used commercially available sub-components and mounted them on a thin plastic with printed interconnections and coated them for bio-compatibility. Devices were implanted in porcine models during one week. We could during this time measure the in-vivo body temperature through skin and subcutaneous tissue ranging in thickness from some mm to a couple of cm. The implanted sensor devices are mounted on thin, printed-electronics plastic sheets where the coils and conductors are designed with different types of materials. The choice of materials is done in order to offer a low-cost solution to read out data from in-vivo sensors. We compile measured data, practical results and guidelines, together with theoretical results referring to the design of the implanted inductive NFC coil as well as the energy transfer from one mobile device to another.

  • 34.
    Zötterman, Johan
    et al.
    Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper.
    Bergkvist, Max
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Iredahl, Fredrik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Linköpings universitet, Medicinska fakulteten.
    Monitoring of partial and full venous outflow obstruction in a porcine flap model using laser speckle contrast imaging2016Inngår i: Journal of Plastic, Reconstructive & Aesthetic Surgery, ISSN 1748-6815, E-ISSN 1532-1959, Vol. 69, nr 7, s. 936-943Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: In microsurgery, there is a demand for more reliable methods of postoperative monitoring of free flaps, especially with regard to tissue-threatening obstructions of the feeding arteries and draining veins. In this study, we evaluated laser speckle contrast imaging (LSCI) and laser Doppler flowmetry (LDF) to assess their possibilities to detect partial and full venous outflow obstruction, as well as full arterial occlusion, in a porcine flap model. Methods: Cranial gluteal artery perforator flaps (CGAPs) were raised, and arterial and venous blood flow to and from the flaps was monitored using ultrasonic flow probes. The venous flow was altered with an inflatable cuff to simulate partial and full (50% and 100%) venous obstruction, and arterial flow was completely obstructed using clamps. The flap microcirculation was monitored using LSCI and LDF. Results: Both LDF and the LSCI detected significant changes in flap perfusion. After partial (50%) venous occlusion, perfusion decreased from baseline, LSCI: 63.5 +/- 12.9 PU (p = 0.01), LDF 31.3 +/- 15.7 (p = 0.64). After 100% venous occlusion, a further decrease in perfusion was observed: LSCI 54.6 +/- 14.2 PU (p amp;lt; 0.001) and LDF 16.7 +/- 12.8 PU (p amp;lt; 0.001). After release of the venous cuff, LSCI detected a return of the perfusion to a level slightly, but not significantly, below the baseline level 70.1 +/- 11.5 PU (p=0.39), while the LDF signal returned to a level not significant from the baseline 36.1 +/- 17.9 PU (p amp;gt; 0.99). Perfusion during 100% arterial occlusion decreased significantly as measured with both methods, LSCI: 48.3 +/- 7.7 (PU, pamp;lt;0.001) and LDF: 8.5 +/- 4.0 PU (pamp;lt;0.001). During 50% and 100% venous occlusion, LSCI showed a 20% and 26% inter-subject variability (CV%), respectively, compared to 50% and 77% for LDF. Conclusions: LSCI offers sensitive and reproducible measurements of flap microcirculation and seems more reliable in detecting decreases in blood perfusion caused by venous obstruction. It also allows for perfusion measurements in a relatively large area of flap tissue. This may be useful in identifying areas of the flap with compromised microcirculation during and after surgery. (C) 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  • 35.
    Zötterman, Johan
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Mirdell, Robin
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Horsten, Sandra
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Medicinska fakulteten.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Methodological concerns with laser speckle contrast imaging in clinical evaluation of microcirculation2017Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, nr 3, artikkel-id e0174703Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background Laser Speckle Contrast Imaging (LSCI) is a non-invasive and fast technique for measuring microvascular blood flow that recently has found clinical use for burn assessment and evaluation of flaps. Tissue motion caused by for example breathing or patient movements may however affect the measurements in these clinical applications, as may distance between the camera and the skin and tissue curvature. Therefore, the aims of this study were to investigate the effect of frame rate, number of frames/image, movement of the tissue, measuring distance and tissue curvature on the measured perfusion. Methods Methyl nicotinate-induced vasodilation in the forearm skin was measured using LSCI during controlled motion at different speeds, using different combinations of frame rate and number of frames/image, and at varying camera angles and distances. Experiments were made on healthy volunteers and on a cloth soaked in a colloidal suspension of polystyrene microspheres. Results Measured perfusion increased with tissue motion speed. The relation was independent of the absolute perfusion in the skin and of frame rate and number of frames/image. The measured perfusion decreased with increasing angles (16% at 60, p = 0.01). Measured perfusion did not vary significantly between measurement distances from 15 to 40 cm (p = 0.77, %CV 0.9%). Conclusion Tissue motion increases and measurement angles beyond 45 decrease the measured perfusion in LSCI. These findings have to be taken into account when LSCI is used to assess moving or curved tissue surfaces, which is common in clinical applications.

  • 36.
    Zötterman, Johan
    et al.
    Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Linköpings universitet, Institutionen för biomedicinska och kliniska vetenskaper, Avdelningen för kirurgi, ortopedi och onkologi.
    Opsomer, Dries
    Department of Plastic and Reconstructive Surgery, University of Ghent, Ghent, Belgium.
    Farnebo, Simon
    Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US. Linköpings universitet, Institutionen för biomedicinska och kliniska vetenskaper, Avdelningen för kirurgi, ortopedi och onkologi.
    Blondeel, Phillip
    Department of Plastic and Reconstructive Surgery, University of Ghent, Ghent, Belgium.
    Monstrey, Stan
    Department of Plastic and Reconstructive Surgery, University of Ghent, Ghent, Belgium.
    Tesselaar, Erik
    Linköpings universitet, Medicinska fakulteten. Region Östergötland, Diagnostikcentrum, Medicinsk strålningsfysik. Linköpings universitet, Institutionen för biomedicinska och kliniska vetenskaper, Avdelningen för kirurgi, ortopedi och onkologi.
    Intraoperative Laser Speckle Contrast Imaging in DIEP Breast Reconstruction: A Prospective Case Series Study2020Inngår i: Plastic and reconstructive surgery. Global open, ISSN 2169-7574, Vol. 8, nr 1, s. e2529-e2529Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Laser speckle contrast imaging (LSCI) is a laser-based perfusion imaging technique that recently has been shown to predict ischemic necrosis in an experimental flap model and predicting healing time of scald burns. The aims were to investigate perfusion in relation to the selected perforator during deep inferior epigastric artery perforator (DIEP) flap surgery, and to evaluate LSCI in assisting of prediction of postoperative complications. METHODS: Twenty-three patients who underwent DIEP-procedures for breast reconstruction at 2 centers were included. Perfusion was measured in 4 zones at baseline, after raising, after anastomosis, and after shaping the flap. The perfusion in relation to the selected perforator and the accuracy of LSCI in predicting complications were analyzed. RESULTS: After raising the flap, zone I showed the highest perfusion (65 ± 10 perfusion units, PU), followed by zone II (58 ± 12 PU), zone III (53 ± 10 PU), and zone IV (45 ± 10 PU). The perfusion in zone I was higher than zone III (P = 0.002) and zone IV (P < 0.001). After anastomosis, zone IV had lower perfusion than zone I (P < 0.001), zone II (P = 0.01), and zone III (P = 0.02). Flaps with areas <30 PU after surgery had partial necrosis postoperatively (n = 4). CONCLUSIONS: Perfusion is highest in zone I. No perfusion difference was found between zones II and III. Perfusion <30 PU after surgery was correlated with partial necrosis. LSCI is a promising tool for measurement of flap perfusion and assessment of risk of postoperative ischemic complications.

  • 37.
    Zötterman, Johan
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Tesselaar, Erik
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten.
    Farnebo, Simon
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för Kirurgi, Ortopedi och Onkologi. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Sinnescentrum, Hand- och plastikkirurgiska kliniken US.
    The use of laser speckle contrast imaging to predict flap necrosis: An experimental study in a porcine flap model2019Inngår i: Journal of Plastic, Reconstructive & Aesthetic Surgery, ISSN 1748-6815, E-ISSN 1532-1959, Vol. 72, nr 5, s. 771-777Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: We evaluated the use of laser speckle contrast imaging (LSCI) in the perioperative planning in reconstructive flap surgery. The aim of the study was to investigate whether LSCI can predict regions with a high risk of developing postoperative necrosis. Our hypothesis was that, perioperatively, such regions have perfusion values below a threshold value and show a negative perfusion trend. Methods: A porcine flap model based on the cranial gluteal artery perforator was used. Images were acquired before surgery, immediately after surgery (t = 0), after 30 min (t =30 min), and after 72h (t = 72 h). Regions of interest (ROIs) were chosen along the central axis of the flap. Clinical evaluation of the flap was made during each time point. Results: At t = 72 h, a demarcation line could be seen at a distance of 15.8 +/- 0.4 cm away from the proximal border of the flaps. At t =0, perfusion decreased gradually from the proximal to the distal ROI. At t =30 min, perfusion was significantly lower in the ROI distal to the final demarcation line than that at t = 0, and in all flaps, these ROIs had a perfusion amp;lt;25 PU. At t= 72 h, perfusion in the ROI proximal to this line returned to baseline levels, whereas perfusion in the distal ROI remained low. Conclusions: In our model, a decrease in perfusion during the first 30 min after surgery and a perfusion amp;lt;25 PU at t = 30 min was a predictor for tissue morbidity 72 h after surgery, which indicates that LSCI is a promising technique for perioperative monitoring in reconstructive flap surgery. (C) 2018 Published by Elsevier Ltd on behalf of British Association of Plastic, Reconstructive and Aesthetic Surgeons.

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