Abstract
Monitoring tissue chemistry in patients by microdialysis is likely to become routine in clinical practice Many diagnostic and therapeutic decisions in medical practice are based on measuring blood concentrations of endogenous molecules. Yet most biochemical and pharmacological events take place in the tissues. Assessing tissue chemistry should theoretically provide more accurate data, and this can now be achieved relatively cheaply and minimally invasively with microdialysis. This review describes the technique of microdialysis and its application in clinical research, drug monitoring, and drug development. It also discusses how, in the future, measurement of tissue rather than blood chemistry may become the standard for some clinical investigations. #### Summary points Microdialysis enables the in vivo measurement of tissue chemistry in humans and is feasible in virtually every human organ It is currently being used to monitor brain ischaemia and metabolic control The technique is set to become a standard tool in drug monitoring and development In the future “bedside” microdialysis will allow monitoring of tissue metabolism in a wide range of diseases This article is based on 10 years of personal experience of using microdialysis to monitor tissue chemistry in various clinical settings and on a comprehensive study of the literature. A Medline search at the time of writing provided 1020 articles for “microdialysis and human” and 7277 articles for “microdialysis.” In vivo microdialysis measures the chemical composition of the interstitial tissue fluid—that is, the fluid to which cells and other target structures are directly exposed. In contrast to imaging techniques or biosensors, which serve as detecting tools, microdialysis is a sampling tool and needs to be linked to an analytical device. Depending on the availability of an appropriate analytical assay, virtually every soluble molecule in the interstitial space fluid can be measured by microdialysis. In recent years the use of microdialysis has moved from …