title: Laboratory evaluation of 10 heat and moisture exchangers using simulated aeromedical evacuation conditions.
abstract: Heat and moisture exchangers (HMEs) are used for airway humidification in mechanically ventilated patients and have been evaluated only under hospital conditions. U.S. Air Force aeromedical evacuation transports are performed under rugged conditions further complicated by the cold and dry environment in military aircrafts, and HMEs are used to provide airway humidification for patients. This study evaluated 10 commercial HMEs using a test system that simulated aeromedical evacuation conditions. Although the American National Standards Institute recommends inspired air to be at an absolute humidity value of > or = 30 mg/L for mechanically ventilated patients, the highest absolute humidity by any HME was approximately 20 mg/L. Although none of the HMEs were able to maintain a temperature high enough to achieve the humidity standard of the American National Standards Institute, the clinical significance of this standard may be less important than the relative humidity maintained in the respired air, especially on evacuation flights of short duration.
authors.affiliation: Hyperion Biotechnology, Inc., 13302 Langtry, San Antonio, TX 78248, USA.
authors.forename: Huda S
authors.initials: HS
authors.lastname: Suliman
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Fecura
authors.forename: Jonathan
authors.initials: J
authors.lastname: Baskin
authors.forename: John E
authors.initials: JE
authors.lastname: Kalns
mesh_terms: D017732:Air Ambulances; D000401:Aircraft; D006801:Humans; D006813:Humidity; D012121:Respiration, Artificial / Q000009:adverse effects / Q000295:instrumentation*; D013696:Temperature; D012122:Ventilators, Mechanical