Temperature-induced changes in blood acid-base status: pH and PCO2 in a binary buffer

Abstract

Equations for proton equilibria of a single-phase binary buffer system have been applied to temperature-induced changes in pH and PCO2 of separated dog plasma at constant carbon dioxide content. Predicted behaviour, measured as deltapH/deltaT and deltalog PCO2 /deltaT, and pH and PCO2 as a function of temperature (range 8–45 degrees C), are in reasonable agreement with theory. Theory predicts and data confirm that deltapH/delta T and deltalog PCO2/deltaT functions of temperature; no single “temperature correction factor” is applicable. Comparison of whole blood with binary buffer equations also shows acceptable agreement between theory and experiment. Blood and separated plasma show similar responses in deltapH/deltaT and deltalog PCO2/delta T when compared over identical temperature intervals. For blood or plasma with initial pH (AT 37.5 DEGREES C) values in the range 7.53–7.45 deltapH/delta T (u/ degrees C) values are -0.0139 (37.5–27.5 degrees C) and -0.0192 (19–7 degrees C); comparable deltalog PCO2/deltaT values are 0.0195 (37.5–27.5 degrees C) and 0.0240 (19–7 degrees C). The charge state of protein components in this system remains nearly constant as temperature varies.