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Assessment of blood flow changes in human skin by microdialysis urea clearance
Linköpings universitet, Institutionen för klinisk och experimentell medicin, Hand och plastikkirurgi. Linköpings universitet, Hälsouniversitetet. (Folke Sjöberg)
Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet.
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.
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.
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. Vol. 18, nr 3, s. 198-204
Emneord [en]
microcirculation; laser Doppler perfusion imaging; polarisation light spectroscopy; ischaemia; reperfusion; hypoperfusion; hyperaemia
HSV kategori
Identifikatorer
URN: urn:nbn:se:liu:diva-63115DOI: 10.1111/j.1549-8719.2010.00077.xISI: 000288759900004OAI: oai:DiVA.org:liu-63115DiVA, id: diva2:376551
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
Inngår i avhandling
1. On microvascular blood flow assessment with the new microdialysis urea clearance technique
Åpne denne publikasjonen i ny fane eller vindu >>On microvascular blood flow assessment with the new microdialysis urea clearance technique
2010 (engelsk)Doktoravhandling, 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.

sted, utgiver, år, opplag, sider
Linköping: Linköping University Electronic Press, 2010. s. 69
Serie
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1204
Emneord
microdialysis, microcirculation
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-63116 (URN)978-91-7393-320-9 (ISBN)
Disputas
2010-12-03, Berzeliussalen, Hälsouniversitetet, Campus US, Linköpings universitet, Linköping, 09:00 (svensk)
Opponent
Veileder
Tilgjengelig fra: 2010-12-28 Laget: 2010-12-11 Sist oppdatert: 2012-03-13bibliografisk kontrollert

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