Continuous recording of arterial pO2, pCO2, pH, and O2 saturation in vivo

Abstract

Methods are described for concurrent, continuous, and automatic recording of paO2, paCO2, apH, and SaO2 of the arterial or venous blood. Measurements were obtained by catheterization of vessels as small as 1 mm in diameter. Graphs of these parameters may be compared with similar measurements in tissue, such as the brain, and correlated with records of function (EKG, EEG, pneumograph). Continuously flowing blood was brought into contact with electrodes and a cuvette for measuring pCO2, pO2, pH, and arterial oxygen saturation by means of catheters and an electrode housing and was then returned to the circulation. For arterial measurements, an arteriovenous shunt was used, for venous blood a mechanical pump is necessary. pCO2 was determined by a membrane-covered pH electrode, pO2 by a membrane-covered polarograph electrode, pH by a small glass electrode, SaO2 by a flow-through oximeter cuvette. Alterations in arterial pH influence SaO2 and paO2 in opposite directions (Bohr effect). Brain tissue parameters reflect changes in arterial pO2, pCO2, and pH but often move independently due to localized changes in tissue circulation and metabolism. Submitted on October 10, 1960