Minimum Pressure for a Zero-Prebreathe Pressure Suit 851315

There are two current approaches to reducing the risk of decompression sickness during repeated extravehicular activity (EVA) without prebreathing 100% oxygen. One approach suggests the use of different pressures in the transfer vehicle, the station, and the suit. The other would use advanced pressure-suit technology to build a suit that will make different pressures unnecessary provided the bends-free suit pressure is reasonable and can be readily determined. Research at the USAF School of Aerospace Medicine since November 1982 has been directed at determining this suit pressure using human subjects at simulated altitudes of 16,500 to 10,000 feet (7.8 to 10 psia). An earlier report of this ongoing research showed that bends is not totally eliminated at 7.8 psia. The present study is a continuation of this effort to define a “bends-free” suit pressure with the initial results suggesting that this pressure begins at around 9.5 psia (from a 14.7 psia station).