Analysis of gases and pH of blood at altitude

The accuracy of a system for measuring pH and gas in blood in a changing-altitude environment was studied. No problems were encountered when arterial blood was measured, provided the instrument was properly calibrated. Failure to calibrate to the correct altitude settings caused major variations in measuring oxygen levels in blood. Standard gases used for calibrating were measured at altitude without recalibrating the system; approximately 80% of the oxygen and 90% of the carbon dioxide partial-pressure values were within 3 mm Hg of their expected value. More deviation occurred for Po2 values as the altitude increased. Frequently, the Po2 electrode malfunctioned, particularly above 8000 ft (2438 m). The Corning Blood Gas System, which was used in this study, was capable of making accurate determinations of gas in blood if properly operated and calibrated to specific altitude levels.