Development of a flexible PCO2 microsensor for gastrointestinal pHi monitoring

The intramucosal pH (pHi) is indirectly determined by measuring the PCO₂ in the lumen of the gut, and the bicarbonate ion concentration in an arterial blood sample; the pHi is then calculated using the Henderson-Hasslebach equation. A microsensor is developed to measure the intramural PCO₂. The microsensor is designed as part of a flexible catheter for insertion into the colon or stomach. The sensor satisfied all accuracy and performance criteria after being tested in vivo. The in vivo performance was validated in pigs, with induced intestinal ischemia by comparing the sensor pHi measurements to those determined using a balloon tanometer and a needle pH electrode directly placed in the mucosal tissue