pH stat temperature correction is used to interpret blood gas results by accounting for which variable?

• A. Ambient room temperature
• B. Patient temperature
• C. Altitude
• D. Humidity

Answer: (B)

The main idea is that acid–base interpretation of blood gases must reflect the patient’s actual body temperature. Temperature changes affect the chemistry of carbon dioxide in blood—the solubility of CO2 and the dissociation of carbonic acid shift with temperature, so the same measured pH and PaCO2 correspond to different physiologic states at different temperatures. By correcting to the patient’s core temperature (the pH-stat approach), you interpret the results as they truly exist in the body, not as they would at ambient conditions. Ambient room temperature, altitude, and humidity don’t directly alter the blood’s acid–base chemistry the way patient temperature does, so the correction targets the patient’s temperature.