HMEs, or Heat and Moisture Exchangers, capture heat and water vapor from a patient's exhaled air. Then during inhalation, they add heat and moisture to the inspired air, providing the appropriate humidification. Independent published studies have shown Covidien DAR filter- HMEs to be among the best HMEs in terms of moisture output. A recently published study by Lellouche et al showed that out of 48 other filters and HMEs tested, three DAR Filter HMEs ranked in the top 10 for performance.
