Altitude chamber related adverse effects among 1241 airmen

Altitude chambers are used for training aircrews, but incidents have been reported, including decompression sickness (DCS) and barotrauma. To minimize chamber-related adverse effects we implemented a set of measures, including altitude restriction and a pre-chamber clinical selection (PCS) of subjects before exposure.

We reviewed our records regarding 1254 individuals who were trained from 2003 to 2009. After the first 3 subjects, the maximum altitude of the highest training profile was limited to 43,000 ft (13,106.4 m) instead of 45,000 ft (13,716 m) and, after the first 327 subjects, a clinical evaluation of each trainee was performed by an otolaryngologist before altitude exposure. The evaluation included otoscopy and tympanometry, and subjects with abnormal results were not cleared for altitude exposure. Subjects were grouped by having undergone the highest profile before (3 subjects) or after altitude restriction (8 subjects) and received clinical selection (PCS group, 927 subjects) or not (control group, 327 subjects).

We recorded 32 total adverse effects (overall incidence 2.6%), 21 in the PCS group (2.3%) and 11 in the control group (3.4%). The difference between groups was not significant. Adverse effects included 19 cases of acute barotitis (1.5%), 1 case of DCS (0.08%), and 4 cases of syncope (0.3%). The incidence of barotitis was 1.1% in the PCS group and 2.7% in the control group. The altitude restriction was ineffective in preventing both barotrauma and DCS.

The incidence of adverse effects in our subjects was low and pre-chamber clinical selection appeared to be effective in reducing the risk of barotitis.