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An assessment of calibration and performance of the microdialysis system
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology. (Enheten för Anestesi och Intensivvård)
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
2005 (English)In: Journal of Pharmaceutical and Biomedical Analysis, ISSN 0731-7085, E-ISSN 1873-264X, Vol. 39, no 3-4, 730-734 p.Article in journal (Refereed) Published
Abstract [en]

To improve the reliability of microdialysis measurements of tissue concentrations of metabolic substances, this study was designed to test both the performance and the internal validity of the microdialysis methods in the hands of our research group. The stability of the CMA 600 analyser was tested with a known glucose solution in 72 standard microvials and in 48 plastic vials. To evaluate if variation in sampling time makes any difference in sample concentration (recovery), sampling times of 10, 20 and 30 min were compared in vitro with a constant flow rate of 1 microl/min. For testing of sampling times at different flow rates, an in vitro study was performed in which a constant sample volume of 10 microl was obtained. With the no net flux method, the actual concentration of glucose and urea in subcutaneous tissue was measured. The CMA 600 glucose analysis function was accurate and stable with a coefficient of variability (CV) of 0.2-0.55%. There was no difference in recovery for the CMA 60 catheter for glucose when sampling times were varied. Higher flow rates resulted in decreased recovery. Subcutaneous tissue concentrations of glucose and urea were 4.4 mmol/l and 4.1 mmol/l, respectively. To conclude, this work describes an internal validation of our use of the microdialysis system by calibration of vials and catheters. Internal validation is necessary in order to be certain of adequate sampling times, flow rates and sampling volumes. With this in mind, the microdialysis technique is useful and appropriate for in vivo studies on tissue metabolism.

Place, publisher, year, edition, pages
Elsevier , 2005. Vol. 39, no 3-4, 730-734 p.
Keyword [en]
Calibration, Chemistry; Pharmaceutical/*methods, Drug Industry, Evaluation Studies as Topic, Glucose/analysis, Microdialysis/instrumentation/*methods, Quality Control, Reference Standards, Reproducibility of Results, Technology; Pharmaceutical/*methods, Time Factors, Urea/pharmacology
National Category
Anesthesiology and Intensive Care
URN: urn:nbn:se:umu:diva-6813DOI: 10.1016/j.jpba.2005.04.036PubMedID: 15939565OAI: diva2:146483
Available from: 2007-12-18 Created: 2007-12-18 Last updated: 2010-11-11Bibliographically approved
In thesis
1. Methodological aspects on microdialysis sampling and measurements
Open this publication in new window or tab >>Methodological aspects on microdialysis sampling and measurements
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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
National Category
Anesthesiology and Intensive Care
Research subject
urn:nbn:se:umu:diva-37464 (URN)978-91-7459-097-5 (ISBN)
Public defence
2010-11-26, Norrlands universitetssjukhus, Betula, 6M, Norrlands universitetssjukhus, 90185 Umeå, 09:00 (Swedish)
Available from: 2010-11-11 Created: 2010-11-04 Last updated: 2012-03-06Bibliographically approved

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