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.