EFFECTS OF HYPOBARIC-HYPOXIA ON THE SALIVARY CORTISOL-LEVELS OF AIRCRAFT PILOTS

Introduction: There has been limited characterization of the endocrine stress reactivity of aircraft pilots under the adverse environmental condition of hypobaric-hypoxia. This seems especially true with respec t to using the non-invasive technique of salivary hormonal analysis. T hus, the purpose of this study was to characterize the salivary cortis ol response to such an environmental stress. Methods: Some 53 pilots w ere exposed to 30 min of hypobaric-hypoxia (final pressure, 540 hPa). The salivary cortisol levels were measured at baseline (0 min), at 15 and 30 min into exposure(+15 and +30 min) and 30 min after the exposur e ended (+60 min). The cortisol response of each pilot was classified according to the difference between the +30 min and 0 min values. Resp onder categories were: increase (I), decrease (D) or no change (N). Re sults: Subjects were not evenly distributed among the three response c ategories (p < 0.05). The distributions were as follows; D = 5 pilots (9.4%), N = 17 pilots (32.1%), and I = 31 pilots (58.5%). Further, sig nificant (p < 0.05) changes in cortisol levels were noted over the sam pling times for the D (+15 min to +60 min < 0 min) and I (+15 min to 60 min > 0 min) responders, as well as between the D, N, and I respond ers at the +15 to +60 min sampling times. Conclusions: We conclude tha t no single consistent change in salivary cortisol level occurred amon g the different subjects in response to the level and duration of hypo baric-hypoxia studied.