Am. J. Respir. Crit. Care Med., Vol 153, No. 2, Feb 1996, 694-700.
Development and validation of a technique for continuous monitoring of gastric intramucosal pH
JA Guzman and JA Kruse
Division of Pulmonary and Critical Care Medicine, Wayne State University School of Medicine, Detroit, Michigan, USA.
A novel method for continuously monitoring gastric intramucosal PCO2 and pH
was developed and tested. Gas was continuously circulated through a
modified balloon-tipped catheter connected to an external closed system
fitted with an infrared CO2 sensor to monitor PCO2. Performance of the
capnometric recirculating gas tonometry (CRGT) system was tested in vitro
using an equilibration chamber and in vivo in six anesthetized dogs. Serial
PCO2 measurements were made using CRGT and compared with intermittent PCO2
values obtained by conventional tonometry catheters. In the animal
experiments, gastric intramucosal PCO2 and pH were determined before and
after inducing hypoxia by decreasing the Flo2 to 0.08. After initial
placement, PCO2 determined by the CRGT reached a near plateau within 45
min, and at that time point values were comparable to those obtained by
conventional intermittent tonometry. Significant increases in gastric
intramucosal PCO2 were detectable by CRGT within 5 min of inducing systemic
hypoxia, and there was a concomitant significant decrease in intramucosal
pH. Continuous monitoring of gastric intramucosal PCO2 and pH is feasible,
has potential advantages over conventional methods, and can provide
significant trending information over intervals as short as 5 min.
