Modification of Otis-McKerrow valve for measurement of respiratory water loss.

An apparatus is described that allows a continuous measurement of inspired and expired gas dew-point temperature for the calculation of water loss (Eres) during ventilation. A rapid response dew-point temperature measurement method is described which is based on a small Peltier module. The compact structure with near zero system dead space minimizes potential errors inherent in many techniques used to measure Eres. The simple design and rugged construction permit the incorporation of the apparatus into many manual or personal computer controlled oxygen consumption systems. Collection of data may be done in a variety of ambient temperatures, altitudes, and activity levels. There is also the potential for creating a portable system for field use.