A randomized clinical trial to compare the effects of a heat and moisture exchanger with a heated humidifying system on the occurrence rate of ventilator-associated pneumonia.

BACKGROUND: The purpose of this study was to compare the performance of heat and moisture exchanger filters with heated humidifying systems in the mechanical ventilator circuit on the incidence of ventilator-associated pneumonia (VAP) and bacterial colonization.

METHOD: Two hundred and forty-three consecutive patients who required mechanical ventilation for 48 hours or more in the adult intensive care unit were randomized to either a heat and moisture exchanger (HME) or a heated humidifying breathing circuit.

RESULTS: The VAP rate among the group with HME was 11.4%; the rate among the group with heated humidifying system (HHS) was 15.8%. The difference was not statistically significant. Approximately 68% of the patients in the HME group had no pathogen isolated compared with 50% of the patients in the HHS group. This difference was statistically significant (P =.006). However, the distribution of the pathogens among those patients who had the isolated pathogens was mostly identical in the 2 groups.

CONCLUSION: Even though the study did not find HME to be significantly advantageous over the HHS, in as much as VAP rate is concerned, other advantages such as reduced nurses workload, reduced financial cost, and better safety made HME a more favorable device for use in our adult intensive care unit.