Validation of a novel method for continuous saline tonometry in a porcine model

Only intermittent and semi-continuous tonometric measurement of gastric and intestinal pH(i) is possible with the equipment available today. Earlier w e developed a system for continuous saline tonometry and tested it in vitro . To assess the in vivo reliability of this method for continuous gastroint estinal saline tonometry, a standard tonometer for measurement of intestina l pCO(2) and corresponding pHi was modified to allow continuous perfusion o f physiological saline in a closed system and tested in a porcine model. In I I anaesthetized and haemodynamically stable pigs, two continuous tonomet ry balloons were inserted into the distal small bowel, and a standard tonom etry balloon was used as reference. To test long-term function of the conti nuous tonometers; the research protocol lasted for eight hours. The two con tinuous saline tonometers performed well, and after an equilibration time o f three hours the mean pHi values were stable between 7.35 and 7.43 and bet ween 7.32 and 7.39 respectively. The standard tonometer measured stable pHi values. These preliminary studies indicate that continuous saline tonometr y performs well over eight hours with a small bias and a good precision.