Abstract: A tonometric device for use in hollow viscus tonometry and remote sensing of patient fluid parameters is disclosed in combination with a secondary apparatus, such as a urinary catheter, a nasogastric sump apparatus, or a feeding tube, for example. The device is capable of monitoring certain critical fluid properties of interest, such as oxygen gases and carbon dioxide gases in the wall tissue itself of the patient's organ, rather than monitoring such properties in a lumen of the organ. A walled sampling chamber, which is preferably an inflated balloon member, is provided on an elongated tube, with provisions for positioning the sampling chamber in direct contact with a wall portion of the patient's internal organ.

Abstract: A tonometric device for use in hollow viscus tonometry and remote sensing of patient fluid parameters is disclosed. The device is capable of monitoring certain critical fluid properties of interest, such as oxygen gases and carbon dioxide gases in the wall tissue itself of the patient's organ, rather than monitoring such properties in a lumen of the organ. A walled sampling chamber, which is preferably an inflated balloon member, is provided on an elongated tube, with provisions for positioning the sampling chamber in direct contact with a wall portion of the patient's internal organ.

Abstract: Ischemia in a hollow internal organ can be detected in its incipient stages by obtaining a CO.sub.2 sample from within the organ of interest, measuring the partial pressure of CO.sub.2 sample, measuring the bicarbonate concentration of an arterial blood sample, and on the basis of these two measurements calculating the pH of the wall of the organ. The value of the pH is an indicator of the onset of ischemia in the organ. The CO.sub.2 sample is obtained by a novel catheter, multiple embodiments of which are disclosed. Also disclosed is a method for determining the vitality or adequacy of oxygenation of the whole body, or a solid internal organ, by the measurement of the pH of venous blood.