Ear pain after breathing oxygen at altitude: prevalence and prevention of delayed barotrauma.
BACKGROUND
Military pilots frequently report ear pain with onset several hours after altitude exposure while breathing pure oxygen, but the prevalence of this problem is unknown. A similar problem is described in divers after breathing hyperbaric oxygen and it is related to the oxygen contained in the middle ear.


METHODS
In order to assess the prevalence of delayed ear pain after altitude exposure and investigate the effectiveness of preventive use of a nasal balloon (NB), we studied 88 healthy military jet pilots who were asymptomatic after altitude chamber exposure which included 100% oxygen breathing. A group of 44 subjects received the NB shortly after the chamber and they were advised to use it every hour before going to sleep. A control group of 44 subjects was requested to perform the Valsalva maneuver alone over the same period. All subjects underwent clinical examination by an otolaryngologist and tympanometry just before the chamber exposure and again the day after.


RESULTS
The day after the altitude exposure, 53.4% of subjects reported ear pain. In the treated group, 61.4% of subjects were free of symptoms, compared to 31.8% in the control group (P < 0.01). Tympanogram was abnormal in eight symptomatic subjects and in six asymptomatic.


CONCLUSIONS
Our data suggest that in our subjects there is high prevalence of delayed ear barotrauma after altitude chamber exposure while breathing pure oxygen and the tympanogram may improve the accuracy of the diagnosis in asymptomatic subjects. The nasal balloon appears to be effective for prevention.
Italian Air Force, Logistic Command, Flight Test Center, Aerospace Medicine Department, Rome, Italy.
Angelo
A
Landolfi
Alberto
A
Autore
Francesco
F
Torchia
Mario
M
Ciniglio Appiani
Fabio
F
Morgagni
Giuseppe
G
Ciniglio Appiani
D000328:Adult; D000337:Aerospace Medicine; D000531:Altitude; D001273:Atmosphere Exposure Chambers; D001469:Barotrauma / Q000453:epidemiology* / Q000517:prevention & control*; D004433:Earache / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D010031:Otitis / Q000209:etiology; D038781:Otoscopy; D010100:Oxygen / Q000008:administration & dosage / Q000009:adverse effects*
D010100:Oxygen