Carbon Dioxide Washout of an Emergency Breathing System Mask Modified for Use in the Advanced Seal Delivery System (ASDS) Trainer

摘要

A modified emergency Breathing System full face mask was evaluated for use in the Advanced SEAL Delivery System trainer. The mask contained an oral-nasal cup and two spiral-wound plastic hoses on its inhalation and exhalation openings. Each hose was six feet long with an inside diameter of 1.25 inches and had six rectangular slots cut through the hose wall. The slots were approximately eight inches from one end of each hose. Testing was conducted in an unpressurized hyperbaric chamber that was well ventilated with air. Carbon dioxide (CO2) washout volume - averaged inspired CO2 - was calculated at a respiratory minute ventilation of 22.5 liters per minute (1.min(exp -1)). The mask was ventilated with a mechanical breathing simulator. One hundred per cent CO2 was injected at 0.9 1.min(exp -2) into the breathing loop. Mean CO2 washout was determined for two configurations: normal, with both hoses positioned so that the slotted ends are near the mask; and reversed exhaust, with inhalation hose positioned with its slots near the mask and exhalation hose positioned with the slots away from the mask. By our normalizing for the actual end-tidal CO2 level, the volume-averaged CO2 in the normal configuration was 0.71% and 0.75% with the exhaust reversed. Carbon dioxide washout of the modified emergency breathing system mask with exhaust hose in either configuration is acceptable for use in the ASDS trainer.