liu.seSearch for publications in DiVA
Change search
Refine search result
1 - 22 of 22
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Arildsson, Mikael
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Asker, Claes
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Skin capillary appearance and skin microvascular perfusion due to topical application of analgesia cream2000In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 59, no 1, p. 14-23Article in journal (Refereed)
    Abstract [en]

    Local topical analgesia changes basal skin perfusion and its regulation. In particular, the response induced by local heating, which in nontreated skin comprises a rapidly increased perfusion followed by a normalization within 30 s, is altered to a delayed and persistent perfusion increase. The response dependency to the analgesia cream application time, that is, the intradermal penetration of the analgesics and in which vascular plexa the response occurs, is not known. The aim of this study was to assess changes in the appearance of superficial skin capillaries and skin microvascular perfusion changes due to different application periods of topical analgesia cream (EMLA). Twelve subjects were treated with EMLA and placebo applied to the volar side of each forearm, respectively. The treatment areas were assigned different application times (20 min, 40 min, 1 h, 2 h, and 3 h). The areas were cleared from the creams and shortly thereafter provoked during 9 s with a probe heated to 45°C. To assess capillary number density and skin perfusion, capillary microscopy, and Laser Doppler perfusion imaging (LDPI), respectively, were used. The number density of physiologically active capillary was significantly decreased with longer application times of EMLA (P < 0.005). The LDPI-signal showed a persistent perfusion increase after provocation associated with increasing application time of the cream. This perfusion pattern was not seen after 20 min of treatment, but was present in 9 of 12 subjects after 3 h of treatment. No significant relationship between changes in the capillary number density and the LDF measurement was found. In conclusion, a longer application time and therefore a higher intradermal concentration and a deeper penetration of the analgesics was associated with a delayed and persistent perfusion increase after local heating. There was a discrepancy between changes in capillary number density and skin perfusion, indicating that the perfusion increase does not occur in the capillaries but in the deeper lying vessels. Hence, the contribution of the capillary perfusion to the LDF-signal is smaller than previously anticipated. Capillary number density and presumably their perfusion were decreased with longer application times.

  • 2.
    Arildsson, Mikael
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Nilsson, Gert
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Effects on skin blood flow by provocation during local analgesia2000In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 59, no 1, p. 122-130Article in journal (Refereed)
    Abstract [en]

    Although topical analgesia cream has been used for several years, little is known about its effects on the microcirculation. Previous studies have shown a vasoconstrictive effect after short application times and a vasodilatation after longer application. It has also been shown that vasomotion does not occur in the analgesized skin. The present study was undertaken to investigate the alterations in skin blood perfusion following local cooling, local heating and pin-pricking after the establishment of analgesia. In 11 healthy volunteers, skin analgesia was attained by use of a eutectic mixture of lidocaine and prilocaine (EMLA, Astra Pain Control AB, Sweden) applied to the skin three hours prior to provocation. The changes in skin blood perfusion, after applying three different provocation methods, were studied using the laser Doppler technique. Local cooling and heating to temperatures of +10 and +45°C, respectively, were applied for 9 s by use of a copper probe (Ø12 mm). In the pin-prick provocation method, a combined effect of deflection and penetration of the skin to in total 3 mm was attained. Identical provocation methods were applied to placebo treated and untreated skin areas. After heat provocation, significant differences in the perfusion response between the treatments were seen (P < 0.0001). Skin areas treated with analgesia cream responded with a slow increase in perfusion that persisted beyond the four minute measurement period. Placebo and untreated areas decreased their perfusion over time. After cooling a significant reduction in skin perfusion was seen, irrespective of the treatment. Similarly, after pin-pricking a perfusion increase was seen for all treatments. The findings indicate that topical analgesia influences the myogenic control of the blood flow in those vascular plexa measured by laser Doppler following heat provocation. No differences could be seen in the response to pin-pricking and cooling for the different treatments.

  • 3.
    Barbu, Andreea
    et al.
    Uppsala University, Sweden; Uppsala University, Sweden.
    Jansson, Leif
    Uppsala University, Sweden.
    Sandberg, Monica
    Uppsala University, Sweden.
    Quach, My
    Uppsala University, Sweden.
    Palm, Fredrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. Uppsala University, Sweden.
    The use of hydrogen gas clearance for blood flow measurements in single endogenous and transplanted pancreatic islets2015In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 97, p. 124-129Article in journal (Refereed)
    Abstract [en]

    The blood perfusion of pancreatic islets is regulated independently from that of the exocrine pancreas, and is of importance for multiple aspects of normal islet function, and probably also during impaired glucose tolerance. Single islet blood flow has been difficult to evaluate due to technical limitations. We therefore adapted a hydrogen gas washout technique using microelectrodes to allow such measurements. Platinum micro-electrodes monitored hydrogen gas clearance from individual endogenous and transplanted islets in the pancreas of male Lewis rats and in human and mouse islets implanted under the renal capsule of male athymic mice. Both in the rat endogenous pancreatic islets as well as in the intra-pancreatically transplanted islets, the vascular conductance and blood flow values displayed a highly heterogeneous distribution, varying by factors 6-10 within the same pancreas. The blood flow of human and mouse islet grafts transplanted in athymic mice was approximately 30% lower than that in the surrounding renal parenchyma. The present technique provides unique opportunities to study the islet vascular dysfunction seen after transplantation, but also allows for investigating the effects of genetic and environmental perturbations on islet blood flow at the single islet level in vivo. (C) 2014 The Authors. Published by Elsevier Inc.

  • 4.
    Bergkvist, Max
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Henricson, Joakim
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Iredahl, Fredrik
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Hand and Plastic Surgery.
    Tesselaar, Erik
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Sjöberg, Folke
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Hand and Plastic Surgery.
    Farnebo, Simon
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Hand and Plastic Surgery.
    Assessment of microcirculation of the skin using Tissue Viability Imaging: A promising technique for detecting venous stasis in the skin2015In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 101, p. 20-25Article in journal (Refereed)
    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.

  • 5.
    Elawa, Sherif
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences.
    Mirdell, Robin
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences.
    Tesselaar, Erik
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Medical radiation physics.
    Farnebo, Simon
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Hand and Plastic Surgery.
    The microvascular response in the skin to topical application of methyl nicotinate: Effect of concentration and variation between skin sites2019In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 124, p. 54-60Article in journal (Refereed)
    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.

  • 6.
    Fredriksson, Ingemar
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Measurement depth and volume in laser Doppler flowmetry2009In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 78, no 1, p. 4-13Article in journal (Refereed)
    Abstract [en]

    A new method for estimating the measurement depth and volume in laser Doppler flowmetry (LDF) is presented. The method is based on Monte Carlo simulations of light propagation in tissue. The contribution from each individual Doppler shift is calculated and thereby multiple Doppler shifts are handled correctly. Different LDF setups for both probe based (0.0, 0.25, 0.5, and 1.2 mm source-detector separation) and imaging systems (0.5 and 2.0 mm beam diameter) are considered, at the wavelengths 543 nm, 633 nm, and 780 nm. Non-linear speckle pattern effects are accounted for in the imaging system setups. The effects of tissue optical properties, blood concentration, and blood oxygen saturation are evaluated using both homogeneous tissue models and a layered skin model. The results show that the effect on the measurement depth of changing tissue properties is comparable to the effect of changing the system setup, e.g. source-detector separation and wavelength. Skin pigmentation was found to have a negligible effect on the measurement depth. Examples of measurement depths are (values are given for a probe based system with 0.25 mm source-detector separation and an imaging system with a 0.5 mm beam diameter, respectively, both operating at 780 nm): muscle - 0.55/0.79 mm; liver - 0.40/0.53 mm; gray matter - 0.48/0.68 mm; white matter - 0.20/0.20 mm; index finger pulp - 0.41/0.53 mm; forearm skin - 0.53/0.56 mm; heat provoked forearm skin - 0.66/0.67 mm.

  • 7.
    Golster, Helena
    et al.
    Linköping University, Department of Medical and Health Sciences, Anesthesiology. Linköping University, Department of Biomedicine and Surgery, Plastic Surgery, Hand Surgery and Burns. Linköping University, Faculty of Health Sciences.
    Lindén, Maria
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences.
    Bertuglia, Silvia
    CNR Institute of Clinical Physiology, Pisa, Italy.
    Calantuoni, Antonio
    CNR Institute of Clinical Physiology, Pisa, Italy.
    Nilsson, Gert
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences.
    Sjöberg, Folke
    Linköping University, Department of Medical and Health Sciences, Anesthesiology. Linköping University, Department of Biomedicine and Surgery, Plastic Surgery, Hand Surgery and Burns. Linköping University, Faculty of Health Sciences.
    Red Blood Cell Velocity and Volumetric Flow Assessment by Enhanced High-Resolution Laser Doppler Imaging in Separate Vessels of the Hamster Cheek Pouch Microcirculation1999In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 58, no 1, p. 62-73Article in journal (Refereed)
    Abstract [en]

    An enhanced high-resolution laser Doppler imager (EHR-LDI), configured to fit the demands of a measurement area containing separate microvessels, was evaluated for perfusion measurements in hamster cheek pouch preparations during ischemia, reperfusion, and pharmacologically induced vasodilation and vasoconstriction. Measurements in separate microvessels where the laser beam was smaller than the vessel diameter were referred to as red blood cell (RBC) velocity estimates, as previously validated in vitro, whereas a relative flow index, RFI (mean RBC velocity/tissue area), was introduced as a volumetric flow measure. Microvessel diameter and RBC velocity changes during ischemia, reperfusion, as well as during vasoconstriction and vasodilation correlated to the data obtained from the microscope. Correspondingly, during the described provocations anticipated volumetric flow changes were registered as changes in the RFI. When data on intravessel RBC velocity profiles are presented they reflect a parabolic flow profile usually seen in this size microvessel. The EHR-LDI appears a promising tool for investigation of the microvasculature, as it almost simultaneously provides information on relative changes of both in vivo RBC velocity and volumetric flow (RFI), although the latter estimate needs to be further refined.

  • 8. Gustavsson, U.
    et al.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Nilsson, Gert
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Lewis, D.H.
    Vasomotion in rat skeletal muscle induced by hemorrhage as recorded by laser Doppler flowmetry1991In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, no 42, p. 224-228Article in journal (Refereed)
  • 9.
    Henricson, Joakim
    et al.
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Droog Tesselaar, Erik
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Persson, Karin
    Linköping University, Department of Medicine and Health Sciences, Pharmacology . Linköping University, Faculty of Health Sciences.
    Nilsson, Gert
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Sjöberg, Folke
    Linköping University, Department of Clinical and Experimental Medicine, Burn Unit . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Plastic Surgery, Hand surgery UHL.
    Assessment of microvascular function by study of the dose‐response effects of iontophoretically applied drugs (acetylcholine and sodium nitroprusside): Methods and comparison with in vitro studies2007In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 73, no 2, p. 143-149Article in journal (Refereed)
    Abstract [en]

    Current knowledge about vascular function stems mainly from pharmacological in vitro studies using mounted vascular strips on a strain gauge. We know of no paper that has systematically examined the possibility of assessing the conventional dose–response effects of iontophoresis and laser Doppler investigation of vasoactive substances and compared those relations to data obtained from strips mounted on a strain gauge.

    We used the vasoactive substances acetylcholine (endothelium dependent) and sodium nitroprusside (endothelium independent) and an antagonist (atropine) to enable further investigations in the receptor physiology of iontophoresis.

    Dose–response curves from the iontophoresis experiments showed close similarity to those obtained by vascular strips mounted on a strain gauge. The coefficient of variation (CV) of the dose–response factors found in iontophoresis (both inter and intra experimental variability) was low. The iontophoretic effective dose of 50% (ED50) for acetylcholine and nitroprusside had only CVs of 25% and 26%, respectively, compared with 71% and 77% for the vascular strips. Acetylcholine-induced response was antagonized by iontophoresis of atropine. Contrary to expectations, this antagonism was not competitive.

    The results show that iontophoresis in combination with laser Doppler technology produces reproducible and reliable dose–response curves that picture the vascular effects of vasoactive drugs.

  • 10.
    Häggblad, Erik
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Arildsson, Mikael
    Linköping University, Department of Biomedical Engineering.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Reflection Spectroscopy of Analgesized Skin2001In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 62, no 3, p. 392-400 Article in journal (Refereed)
    Abstract [en]

    Analgesized skin, when subjected to heat stimuli, responds by increasing skin perfusion. This response does not originate from increased perfusion in superficial capillaries, but rather in the deeper lying vessels. The aim of this study was to assess changes in blood chromophore content, measured by reflection spectroscopy, in relation to the perfusion increase, especially regarding the chromophores oxyhemoglobin and deoxyhemoglobin. Eleven normal subjects were treated with analgesic cream (EMLA) and placebo for 20, 40, 60, 120, and 180 min. Individual reactions to local heating were classified as responses if the change in reflection data or the change in perfusion, as measured by laser Doppler blood flowmetry, exceeded 2 standard deviations of normal variation. The increase in blood perfusion or in blood content gave rise to an increased absorption, interpreted as an increase due mainly to the chromophore oxyhemoglobin. The number of responses increased with increased treatment time for EMLA-treated areas. In general, there was a good agreement between both methods; 44 of 55 classifications coincided for the two methods used. In conclusion, analgesized forearm skin, which had been exposed to local heating, responded with an elevated perfusion consisting of oxygenated blood. This strengthens the hypothesis that the flow increase occurs through dilatation of larger deeper lying skin vessels and not in the capillaries.

  • 11.
    Jonasson, Hanna
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Fredriksson, Ingemar
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering. Perimed AB, Datavägen 9A, 175 43 Järfälla, Stockholm, Sweden.
    Pettersson, Anders
    Perimed AB, Datavägen 9a, 175 26 Järfälla-Stockholm.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Oxygen saturation, red blood cell tissue fraction and speed resolved perfusion — A new optical method for microcirculatory assessment2015In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 102, p. 70-77Article in journal (Refereed)
    Abstract [en]

    We have developed a new fiber-optic system that combines diffuse reflectance spectroscopy (DRS) and laser Doppler Flowmetry (LDF) for a multi-modal assessment of the microcirculation. Quantitative data is achieved with an inverse Monte Carlo algorithm based on an individually adaptive skin model. The output parameters are calculated from the model and given in absolute units: hemoglobin oxygen saturation (%), red blood cell (RBC) tissue fraction (%), and the speed resolved RBC perfusion separated into three speed regions; 0–1 mm/s, 1–10 mm/s and above 10 mm/s (% mm/s). The aim was to explore microcirculatory parameters using the new optical method, integrating DRS and LDF in a joint skin model, during local heating of the dorsal foot and venous and arterial occlusion of the forearm in 23 healthy subjects (age 20–28 years). There were differences in the three speed regions in regard to blood flow changes due to local heating, where perfusion for high speeds increased the most. There was also a high correlation between changes in oxygenation and changes in perfusion for higher speeds. Oxygen saturation at baseline was 44% on foot, increasing to 83% at plateau after heating. The larger increase in perfusion for higher speeds than for lower speeds together with the oxygenation increase during thermal provocation, shows a local thermoregulatory blood flow in presumably arteriolar dermal vessels. In conclusion, there are improved possibilities to assess microcirculation using integrated DRS and LDF in a joint skin model by enabling both oxygenation and speed resolved blood flow assessment simultaneously and in the same skin site. Output parameters in absolute units may also yield new insights about the microcirculatory system.

  • 12.
    Karlander, Lars-Erik
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of surgery. Östergötlands Läns Landsting, Reconstruction Centre, Department of Plastic Surgery, Hand surgery UHL.
    Henriksson, J
    Sjöberg, Folke
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of surgery. Östergötlands Läns Landsting, Reconstruction Centre, Department of Plastic Surgery, Hand surgery UHL.
    Acidosis in muscle tissue distal to vascular contusion despite unchanged global blood flow in rats: An uncoupling of microvascular blood flow and metabolism?2005In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 70, no 1-2, p. 111-115Article in journal (Refereed)
    Abstract [en]

    Studies using a contusion trauma model have shown that the femoral artery of the rat remains patent in 85% despite a severe vessel injury. A significant increase in tissue oxygenation (PtO2) has been found despite only a minor effect on blood flow (<20% decrease) on the muscle surface distal to the injury indicating a disturbed relationship between microvascular blood flow and metabolism. The aim of the present study was to further study the interplay between microvascular blood flow and metabolism within the distal muscle using an ethanol clearance technique (blood flow) in conjunction to the determination of an ischemia marker (lactate) by use of microdialysis. Although skeletal muscle blood flow remained unaltered as assessed by ethanol clearance, skeletal muscle lactate levels increased significantly (P < 0.001) post-trauma in both legs. The increase was initially higher, faster and the increase over time larger in the trauma leg as compared to the control leg (P < 0.001). These findings indicate a systemic effect of the trauma. Further, it suggests a functional impairment of the relationship between microvascular blood flow and/or muscle metabolic processes when the trauma is directed towards the supplying blood vessel. The reason for this anaerobic insult as found in this study compared to the presence of a local increase in PtO2 in the trauma leg as shown in our previous study is suggestive of an microvascular blood flow and tissue metabolism uncoupling. © 2005 Elsevier Inc. All rights reserved.

  • 13. Kvernebo, K.
    et al.
    Staxrud, L.E.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Assessment of Human Muscle Blood Perfusion with Single-Fiber Laser Doppler Flowmetry.1990In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 39, p. 376-385Article in journal (Refereed)
  • 14.
    Lindén, Maria
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences.
    Golster, Helena
    Linköping University, Department of Biomedicine and Surgery, Plastic Surgery, Hand Surgery and Burns. Linköping University, Department of Medical and Health Sciences, Anesthesiology. Linköping University, Faculty of Health Sciences.
    Bertuglia, Silvia
    CNR Institute of Clinical Physiology, Via Trieste, Pisa, Italy.
    Colantuoni, Antonio
    CNR Institute of Clinical Physiology, Via Trieste, Pisa, Italy.
    Sjöberg, Folke
    Linköping University, Department of Biomedicine and Surgery, Plastic Surgery, Hand Surgery and Burns. Linköping University, Department of Medical and Health Sciences, Anesthesiology. Linköping University, Faculty of Health Sciences.
    Nilsson, Gert
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences.
    Evaluation of Enhanced High-Resolution Laser Doppler Imaging in an in Vitro Tube Model with the Aim of Assessing Blood Flow in Separate Microvessels1998In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 56, no 3, p. 261-270Article in journal (Refereed)
    Abstract [en]

    An enhanced high-resolution laser Doppler imaging (EHR-LDI) technique intended for visualization of separate microvessels was evaluated by use ofin vitroflow models. In EHR-LDI, a laser beam focused to a half-power diameter less than 40 μm successively scans the tissue under study in steps of 25 μm. Spatial blood flow variations within microvascular structures of 1.5 × 1.5 mm are rendered by 64 × 64 measurement sites. Individual microvessel diameters could be estimated and an average difference of 11 μm compared to microscopic measurements was obtained. For the flow algorithm used, the LDI output signal was found to scale linearly with average velocity (0–3.5 mm/s) when a plastic tube of inner diameter 175 μm was perfused with human blood (correlation coefficient 0.99). The LDI output signal was further found insensitive to hematocrit variations in the range 16–44%. Due to the limited laser light penetration in blood, a reduction in the LDI output signal was observed as the inner tube diameters were successively changed from 280 to 1400 μm.

  • 15.
    Mirdell, Robin
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Hand and Plastic Surgery.
    Lemstra-Idsardi, Aukje Nienke
    Univ Twente, Netherlands.
    Farnebo, Simon
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Hand and Plastic Surgery.
    Tesselaar, Erik
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences.
    The presence of synchronized perfusion dips in the microcirculation of the resting nail bed2019In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 121, p. 71-81Article in journal (Refereed)
    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.

  • 16.
    Rousseau, Andreas
    et al.
    Linköping University, Department of Medical and Health Sciences, Anesthesiology. Linköping University, Faculty of Health Sciences.
    Steinwall, Ingrid
    Linköping University, Department of Medical and Health Sciences, Anesthesiology. Linköping University, Faculty of Health Sciences.
    Woodson, RD
    Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA.
    Sjöberg, Folke
    Linköping University, Department of Medical and Health Sciences, Anesthesiology. Linköping University, Faculty of Health Sciences.
    Hyperoxia decreases cutaneous blood flow in high-perfusion areas2007In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 74, no 1, p. 15-22Article in journal (Refereed)
    Abstract [en]

    The mechanism by which hyperoxia decreases blood flow is still not understood. Hyperoxemia-induced vasoconstriction is known to occur in many organs, including brain and retina, skeletal muscle, and myocardium. Whether this also occurs in skin is unknown.

    This study was conducted in healthy volunteers exposed intermittently to 100% oxygen (FIO2 1.0). Perfusion of forearm skin was measured by laser Doppler imaging (LDI). In series 1, it was measured in 7 subjects before, during, and after 15 min of oxygen breathing. In series 2, flow was measured, also during air and O2 breathing, after perfusion was raised by (a) sympathetic blockade (induced by a topically applied local anesthetic) (n = 9) and by (b) current-induced vasodilation (n = 8).

    In normal unperturbed skin, there was no significant change with hyperoxia. When basal perfusion was raised by topical anesthesia or by current, there was also no change in mean perfusion overall with hyperoxia. However, areas with the highest perfusion (upper decile) showed a significant perfusion decrement with hyperoxia (− 30% and − 20%, respectively; p < 0.001).

    Vasoconstriction with hyperoxia has been demonstrated in human skin. The fact that it is observed only when flow is increased above basal levels and then only in high-flow vessels suggests that cutaneous blood flow control is primarily regulated by variables other than oxygen.

  • 17. Staxrud, L.E.
    et al.
    Jacobsson, A
    Kvernebo, Kurt
    Ullevål sjukhus Universitetet i Oslo.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Spatial and temopral Evaluation of locally induceed skin trauma recorded with laser doppler techniques1996In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 51, p. 69-79Article in journal (Refereed)
  • 18. Staxrud, L.E.
    et al.
    Kvernebo, K.
    Salerud, Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Acute effects of local tissue trauma on skin perfusion evaluated with laser Doppler flowmetry1991In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 42, p. 179-186Article in journal (Refereed)
  • 19.
    Strömberg, Tomas
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Sjöberg, Folke
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Hand and Plastic Surgery.
    Bergstrand, Sara
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Temporal and spatiotemporal variability in comprehensive forearm skin microcirculation assessment during occlusion protocols2017In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 113, p. 50-55Article in journal (Refereed)
    Abstract [en]

    Forearm skin hyperemia during release after brachial occlusion has been proposed for evaluating peripheral arterial disease and endothelial dysfunction. We used a novel fiberoptic system integrating Laser Doppler Flowmetry and Diffuse Reflectance Spectroscopy for a comprehensive pointwise model based microcirculation characterization. The aim was to evaluate and compare the temporal and the spatiotemporal variabilities in forearm skin microcirculation parameters (speed resolved perfusion; low speed amp;lt; 1 mm/s, Perf(SR),(amp;lt; 1); mid-speed 1-10 mm/s, high speed amp;gt; 10 mm/s, and total perfusion (Perf(SR),(tot)); the concentration and oxygenation of red blood cells, C-RBC and S-O2). Ten healthy subjects underwent arterial and venous forearm occlusions (AO, VO), repeated within one week. The repeatability was calculated as the coefficient of variation (CV) and the agreement as the intra-class correlation co-efficient (ICC). The temporal CVs for conventional perfusion, Perf(conv), Perf(SR),(tot), C-RBC and S-O2 were 14%, 12%, 9% and 9%, respectively, while the ICC were amp;gt; 0.75 (excellent). The perfusion measures generally had a higher spatiotemporal than temporal variability, which was not the case for S-O2 and C-RBC. The corresponding spatiotemporal CVs were 33%, 32%, 18% and 15%, respectively. During VO, C-RBC had a CV amp;lt; 35% and ICC amp;gt; 0.40 (fair-good), and after release this was the case for C-RBC (AO and VO), S-O2 (VO) and Perf(SR), (amp;lt; 1) (VO). In conclusion, the skin microcirculation parameters showed excellent temporal repeatability, while the spatiotemporal repeatability especially for perfusion was poorer. The parameters with acceptable repeatability and fair-good agreement were: C-RBC during and after release of VO, the Perf(SR), (amp;lt; 1) after release of VO, the S-O2 and the C-RBC after release of AO. However, the value of these parameters in discriminating endothelial function remains to be studied. (C) 2017 Elsevier Inc. All rights reserved.

  • 20.
    Tesselaar, Erik
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Nezirevic Dernroth, Dzeneta
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Farnebo, Simon
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Hand and Plastic Surgery.
    Acute effects of coffee on skin blood flow and microvascular function2017In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 114, p. 58-64Article in journal (Refereed)
    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.

  • 21.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Braverman, I.M.
    Silverman, D.G.
    Nilsson, Gert
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Spatial heterogeity in normal skin perfusion recorded with laser Doppler imaging and flowmetry1994In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 48, no 1, p. 26-38Article in journal (Refereed)
    Abstract [en]

    Spatial and temporal variations in forearm skin perfusion captured by laser Doppler perfusion imaging (LDI) have been compared with topographic maps recorded by laser Doppler flowmetry. In order to determine the shortest LDI sampling time required at each measurement site, with an adequate signal-to-noise ratio and with the ability to display the heterogeneity in skin perfusion, the noise-limited resolution of the LDI system as well as various sampling times were tested. The noise-limited resolution for medium and high light intensities were less than 0.5% (temporal) and 0.3% (spatial) of full scale. A sampling time of 1 sec was selected and image presentation was made by performing bilinear interpolation between perfusion values. The same area (10 x 10 mm) was mapped with LDI and topographic mapping at seven different sites. In addition, a larger area covering the surrounding skin was recorded with LDI. The small area recordings with LDI and topographic mapping could be identified in the larger LDI image. High-and low-perfusion spots coincided between the two systems. Temporal variations were studied by repeated LDI recordings of the same areas as above. Small spots were selected in the areas and plotted versus time. Without provocation, the total perfusion changes at each spot showed large variations, but the relative perfusion levels between neighboring spots persisted. Provocation with heat increased the perfusion in all spots.

  • 22.
    Wårdell, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Nilsson, Gert
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Duplex laser Doppler perfusion imganing1996In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 52, p. 171-182Article in journal (Refereed)
1 - 22 of 22
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf