Methodological aspects on microdialysis sampling and measurements
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Background: The microdialysis (MD) technique is widely spread and used both experimentally and in clinical practice. The MD technique allows continuous collection of small molecules such as glucose, lactate, pyruvate and glycerol. Samples are often analysed using the CMA 600 analyser, an enzymatic and colorimetric analyser. Data evaluating the performance of the CMA 600 analysis system and associated sample handling are sparse. The aim of this work was to identify sources of variability related to handling of microdialysis samples and sources of error associated with use of the CMA 600 analyser. Further, to develop and compare different application techniques of the microdialysis probes both within an organ and on the surface of an organ.
Material and Methods: Papers I and II are mainly in vitro studies with the exception of the No Net Flux calibration method in paper I where a pig model (n=7) was used to examine the true concentration of glucose and urea in subcutaneous tissue. Flow rate, sampling time, vial and caps material and performance of the analyser device (CMA 600) were examined. In papers III and IV normoventilated anaesthetised pigs (n=33) were used. In paper III, heart ischemia was used as intervention to compare microdialysis measurements in the myocardium with corresponding measurements on the heart surface. In paper IV, microdialysis measurements in the liver parenchyma were compared with measurements on the liver surface in association with induced liver ischemia. All animal studies were approved by the Animal Experimental Ethics Committee at Umeå University Sweden.
Results: In paper I we succeeded to measure true concentrations of glucose (4.4 mmol/L) and Urea (4.1 mmol/L) in subcutaneous tissue. Paper II showed that for a batch analyse of 24 samples it is preferred to store microdialysis samples in glass vials with crimp caps. For reliable results, samples should be centrifuged before analysis. Paper III showed a new application area for microdialysis sampling from the heart, i.e. surface sampling. The surface probe and myocardial probe (in the myocardium) showed a similar pattern for glucose, lactate and glycerol during baseline, short ischemic and long ischemic interventions. In paper IV, a similar pattern was observed as in paper III, i.e. data obtained from the probe on the liver surface showed no differences compared with data from the probe in liver parenchyma for glucose, lactate and glycerol concentrations during baseline, ischemic and reperfusion interventions.
Conclusion: The MD technique is adequate for local metabolic monitoring, but requires methodological considerations before starting a new experimental serie. It is important to consider factors such as flow rate, sampling time and handling of samples in association with the analysis device chosen. The main finding in this thesis is that analyses of glucose, lactate and glycerol in samples from the heart surface and liver surface reflect concentrations sampled from the myocardium and liver parenchyma, respectively.
Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2010. , 59 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1380
Microdialysis, liver ischemia, heart ischemia, epicardium, liver parenchyma, CMA 600, metabolism
Anesthesiology and Intensive Care
Research subject Anaesthesiology
IdentifiersURN: urn:nbn:se:umu:diva-37464ISBN: 978-91-7459-097-5OAI: oai:DiVA.org:umu-37464DiVA: diva2:360737
2010-11-26, Norrlands universitetssjukhus, Betula, 6M, Norrlands universitetssjukhus, 90185 Umeå, 09:00 (Swedish)
Ungerstedt, Urban, Professor emeritus
Winsö, Ola, ProfessorHaney, Michael, DocentÅberg, Anna-Maja, Sjukhuskemist
List of papers