Gastrointestinal tonometry: Basic principles and recent advances in monitoring regional CO2 metabolism

In the quest to improve outcome in critically ill patients, clinicians have embraced many monitoring modalities in the hope that the sheer quantity of data would assist in the detection and treatment of pathophysiological der angements, Gastrointestinal tonometry has been used increasingly in both th e basic science laboratory and the critical care unit, as demonstrated by i ts mention in more than 800 publications in the medical literature. Tonomet ric determination of regional PCO2 is becoming more and more available for clinical use in the intensive care unit (ICU) setting. As reflected by its reluctant acceptance in some circles, however, questions remain surrounding the optimal use of gastrointestinal tonometry and its applications in clin ical medicine. This review discusses the physiological basis for using tono metry, as well as many of the studies supporting its role as a monitor of p erfusion and local oxidative metabolism.