The article by Brashear et al states, "The need for determining the venous CO, value as part of 'electrolytes' is probably questionable if arterial blood gas determinations are available... Indeed, if arterial pH and Paco2 values are available, we can think of no situation in which venous CO, levels would have clinical relevance." While in agreement with their belief that current practice mandates that arterial pH, Paco2, and Pao2 values be used in the evaluation and treatment of acid-base problems, I disagree with their emphasis that venous CO, values are not of clinical relevance.
The total plasma venous CO, content may, for clinical purposes, be equated with serum bicarbonate.1 In fact, their study confirmed the close, statistically significant linear correlation between the actual calculated arterial HCO -3 and the measured venous CO2 levels. The finding of an abnormal venous CO, content or abnormal anion gap, as part of the "electrolytes,"