Indications for Measurement of Total Carbon Dioxide in Arterial Blood

There is increasing evidence of variability in P!(i’, the practi-cal dissociation coefficient used in the Henderson-Hassel-batch equation to calculate arterial bicarbonate from mea-surements of arterial pH and 1O2 The case presented here illustrates not only potential technical artifacts in arterial blood sampling, which can confuse, but also irreconcilable differences in the values of calculated arterial bicarbonate vs measured arterial and venous total carbon dioxide (carbon dioxide content). Measurements of total carbon dioxide in arterial blood will resolve such conflicts, particularly for acutely ill patients, and will reflect the correct bicarbonate measurements for use in therapeutic decisions. Addftlonal Keyphrases: p!(, ’. arterial total CO2 venous total CO2 acid-base management. pediatric chemistiy The diagnosis of acid-base disorders requires properl