The measurement of gastro-intestinal intramucosal carbon dioxide tension by semi-continuous air tonometry

Objective: To evaluate a new method of air tonometry to assess gastro-intestinal intramucosal pH (pHi) and to assess the utility of intramucosal carbon dioxide tension (PrCO2), in isolation or in conjunction with arterial carbon dioxide tension, in order to identify patients with decreased pHi. Design: A prospective study of critically ill intensive care patients. Setting: A 12-bed university hospital intensive care unit. Methods: Patients in whom pulmonary and systemic arterial catheterisation were used for the management of clinical shock were studied. Semi-continuous air tonometry was used. Blood gas analysis and haemodynamic studies were performed as clinically indicated. At the same time PrCO2 and end-tidal carbon dioxide tensions (ETCO2) were obtained. Correlation coefficients for PrCO2, alone or referenced to arterial carbon dioxide (PaCO2) and ETCO2, and pHi were calculated. Correlation coefficients were also calculated between PrCO2, pHi and conventional haemodynamic parameters. Results: Eleven p...