Arm arterial occlusion cuffs as a means of alleviating high +Gz-associated arm pain.

In an aircraft used under sustained high +Gz conditions, if the stick and throttle are positioned such that the pilot's hands are 20 cm or more below heart level, the consequent rise in forearm venous pressure (FVP) may give rise to arm pain, which is exacerbated by positive pressure breathing for G protection (PBG). This study examined the use of arm arterial occlusion cuffs (AAOC) as a means of pain alleviation. Six subjects were exposed on a human centrifuge to a simple acceleration profile of +7 Gz for 15 s, (onset rate 1 G.s-1), and to a complex profile of +4.8 Gz for 10 s followed by +7 Gz for 10 s, repeated 3 times. Subjects wore full coverage anti-G trousers, used PBG (+2 Gz out-in and 10 mm Hg/G), and performed runs with and without inflation of AAOC, during which invasive measurement of FVP was made. During the simple acceleration profile without AAOC, FVP rose to a mean peak of 209 mm Hg and arm pain was severe. With inflation of the AAOC, FVP rise was curtailed at a mean peak of 158 mm Hg and pain was absent. However, during sequential +7 Gz plateaus of the complex profile, AAOC inflation was associated with serially increasing FVP, which was significantly higher than that without AAOC inflation (p < 0.05 and p < 0.001 for second and third plateaus, respectively), giving rise to immediate and severe arm pain. Therefore, the use of arm arterial occlusion as a means of alleviating arm pain is unsuccessful.