A comparison of central venous and arterial blood gas values in the critically ill.

Abstract

Forty-one patients in an intensive care unit were studied with simultaneous central venous and femoral-arterial blood gas studies. The data obtained indicate that central venous blood samples are a reliable practical substitute for arterial sampling in assessing metabolic abnormalities in the acid-base status of the patient. However, central venous blood is at best a rough screening procedure in the assessment of respiratory acid-base abnormalities. In these 41 cases it was found that if the central venous blood gases were normal, then the arterial blood gases were invariably within the normal range, making arterial puncture unnecessary. In smaller hospitals, where physicians are not constantly in attendance, it would appear from these data that central venous blood gas analysis may substitute for arterial puncture in assessing the metabolic acid-base status of the patient, and, if the venous results are normal, it can be assumed that the arterial pressures will be within normal limits.