A Reappraisal of the Multiple Gauze Heat and Moisture Exchanger

Abstract

The multiple gauze heat and moisture exchanger was assessed under standardized conditions, at five levels of predetermined fresh gas humidity. As predicted theoretically, the unit functioned best when presented with fresh gases with high water vapour content. The ordinary unit moistened arid gases during inspiration to a level unacceptable for prolonged use. Unheated simple humidification systems dampen anhydrous stored gases and combined with the standard condenser-humidifier produce a microclimate suitable for entry into the trachea during spontaneous or controlled ventilation. Quadrupling the number of gauzes improved heat and moisture exchange with all but the saturated fresh gases. However, there was a considerable increase in weight.