PERFORMANCE OF A HYDROPHOBIC HEAT AND MOISTURE EXCHANGER AT DIFFERENT AMBIENT-TEMPERATURES

Objective: To evaluate the effect of different room temperatures on hydrophobic heat and moisture exchangers (HME) humidifying capability and efficiency. Methods: Stock HMEs were tested in vitro using an already described test model, with separation of inspiratory and expiratory gas. Absolute humidity (AH) was measured by means of dry-wet dual thermocouple, and HME efficiency was computed as the ratio between expired to inspired AH, at room temperature of 20 and 26-degrees-C. Results: Inspired gas temperature and AH were significantly higher at 26 than at 20-degrees-C; since expired AH remained substantially unchanged, HME efficiency was also higher in warmer environment. Conclusions: Hydrophobic HMEs appear to be affected by room temperature, increasing their humidifying ability and their efficiency with its rise.