A Continuous Analyzer for Monitoring Respiratory Gases and Expired Radioactivity in Clinical Studies

A system for the continuous monitoring of gas exchange as well as 14CO2 from metabolic studies is described. The analyzer incorporates modifications over previously published systems. These modifications include accurate control of analyzer pressure for stable baselines during the long periods of measurement, accurate control of temperature, the measurement of oxygen consumption during high oxygen patient therapy, the measurement of oxygen consumption of patients on a mechanical respirator, and describes a unique flux system to calibrate the analyzer detectors. The closed system provides expired breath data for O2, CO2, and 14CO2 on critically ill patients for long periods of time without stressing the patient and without using a face mask or mouthpiece. These data allow for the calculation of daily energy expenditures of hypermetabolic patients and for the assessment of various metabolic responses with 14C substrates.