The lessons learned in the care of combat casualties throughout time have been vitally important to the improvement of military medicine. However, often the lessons learned were essentially personal, because the ability to transmit those lessons to other medical personnel was not systematized and organized. In past wars, the transmission of those lessons to other care providers was difficult and often long after the fact. Consultant visits were made and War Medicine conferences were held, but policy changes and actual changes in the mechanisms to provide care often lagged. Lessons learned often were not widely spread until years later. New capabilities in medical communications have permitted the development of real-time casualty care information exchange and rapid policy decision-making. This article describes one such effort.

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.

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