Evaluation of a Portable Helicopter Oxygen Delivery System

Rotary-wing aircrew can be repeatedly exposed to moderately high altitude (up to 18,000 feet pressure altitude), making hypoxia and its performance effects a real hazard. Accordingly, USAARL was tasked to evaluate a portable oxygen system for potential use by U.S. Army helicopter aircrew. The system described below provided capability for oxygen production, charging of the portable system, as well as final use by aircrew. The objectives of the investigation were to determine if the system can adequately protect aircrew from hypoxia at altitude, to assess the integration of the device into existing Aviation Life Support Equipment (ALSE), and to verify ease of use. Eighteen subjects were exposed to altitudes of 10, 15, and 18 thousand feet with and without exercise. Throughout the study, the subjects' SpO2 (peripheral hemoglobin oxygen saturation) was continuously monitored. Two criterion values were selected: 91 %, above which no cognitive deficit is expected, and 80%, below which significant cognitive deficits are more frequent. Mean SpO2 declined significantly with increasing altitude whether the subjects were on or off oxygen. With the oxygen system in use (nasal cannula), mean SpO2 levels were above 91%, significantly better than without supplemental oxygen. Post exercise SpO2 was significantly lower (p0.001, paired t-test) than pre-exercise for both mask and cannula conditions. The system provided adequate oxygenation (defined as SpO2 91%) at low levels of exertion up to 18,000 feet, but oxygenation dropped with exercise at the higher altitudes. These findings supported recommendations to the customer for operational use and further research. See also ADM002075. Presented at the Army Science Conference (25th) held in Orlando, Florida on 27-30 November 2006. The original document contains color images.