In vitro validation of gastric air tonometry using perfluorocarbon FC 43 and 0.9% sodium chloride

Abstract

Monitoring splanchnic perfusion by means of gastric intramucosal tonometry is carried out using saline, or more recently, air tonometry using the Tonocap. The objective of this study was the validation of the Tonocap in saline and perfluorocarbon FC 43. The two methods underestimated the predefined PCO2 value by an average of 10%, with clinically acceptable precision. Accuracy of the Tonocap improved at high PCO2 values (9.33 and 9.94 kPa), whereas saline tonometry was superior at low PCO2 values (3.99 and 3.75 kPa). The Tonocap provides a fast and reliable estimation of the PCO2, and with the revised software requiring only 10 min of equilibration, will increase the comparability of future studies.

Sublingual capnometry: a non-invasive measure of microcirculatory dysfunction and tissue hypoxia

“…Air tonometry, particularly in conjunction with an automated system, has a number of advantages when compared with conventional saline tonometry. Unlike saline tonometry, in vitro studies have demonstrated that air tonometry has a very low bias with excellent precision (Graf et al 2000, Barry et al 1998, Tzelepis et al 1996. Furthermore, automated air tonometry has an equilibration time of less than 20 min and being fully automated may eliminate potential sources of error associated with saline tonometry.…”

“…While air tonometry has simplified the measurement process (over saline tonometry) and eliminated the possible errors associated with the use of non-buffered saline this technology has a number of limitations (Graf et al 2000, Barry et al 1998, Tzelepis et al 1996, Taylor et al 1997, Dullenkopf et al 2002. Gastric tonometry is logistically and practically difficult and this may be the main factor which has prevented the widespread use of this technology.…”

Regional carbon dioxide monitoring to assess the adequacy of tissue perfusion

“…Air tonometry, particularly in conjunction with an automated system has a number of advantages when compared with conventional saline tonometry. Unlike saline tonometry, in-vitro studies have demonstrated that air tonometry has a very low bias with excellent precision [44][45][46]. Furthermore, automated air tonometry has an equilibration time of less than 20 minutes and being fully automated may eliminate potential sources of error associated with saline tonometry.…”

“…While air tonometry has simplified the measurement process (over saline tonometry) and eliminated the possible errors associated with the use of non-buffered saline this technology has a number of limitations [44][45][46]85,86]. Gastric tonometry is logistically and practically difficult and this may be the main factor that has prevented the widespread use of this technology.…”