Instrumentation for monitoring oxygen consumption using a replenishment technique.

An instrument to measure patient oxygen consumption simply and accurately has been built using a replenishment technique. Oxygen is added to the patient's exhaled gas until its oxygen concentration is the same as the oxygen concentration of the inhaled gas. The rate at which oxygen is added is a measure of the patient's oxygen consumption. Bench tests show that oxygen consumption is measured with an accuracy of +/- 2.3 percent and human tests show an accuracy of +/- 5.9 percent. The instrument interfaces easily with a mechanical ventilator and is readily accepted by the clinician.