Sensitivity of Breath-to-Breath Gas Exchange Measurements to Expiratory Flow Errors

This is the authors' abstract. We don't add key points for this paper.

During expiration, fluctuations in gas composition, water vapor, and temperature result in flowmeter errors when the flowmeter is calibrated for a given ambient inspiratory gas. In this paper, we indicate that alternative analytical methods of caleulating breath-to-breath gas exchange exhibit differing sensitivities to this error. A theoretical sensitivity analysis is verified by O2 consumption records from rest to exhausting exercise. We conclude that an error sensitivity of less than one is achieved by a method that incorporates measurements of nitrogen flow into and out of the lung, and includes the analysis of breath-to-breath changes in lung volume.