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

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.