Cardiorespiratory Assessment of Decongestant-Antihistamine Effects on Altitude, +Gz, and Fatigue Tolerances
FEDERAL AVIATION ADMINISTRATION WASHINGTON DC OFFICE OF AVIATION MEDICINE
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Decongestants and antihistamines are known to produce effects capable of adversely modifying physiological function and psychomotor task performance. Because of relevance to safe pilot performance, the effects of single doses of two decongestant-antihistamine preparations Compound A and Compound B, or a placebo on cardiorespiratory responses to two equally spaced 2Gz tests during separate 2-hour exposures at ground level GL 1,274 ft MSL and 12,500 ft chamber altitude were assessed. Postaltitude fatigue was assessed by cardiorespiratory responses to submaximal bicycle ergometry. Compound A and Compound B appeared to exert no significant detrimental effects on short-duration postaltitude ergometric fatigability. With two exceptions, all combinations of medication, altitude, and Gz were well tolerated. Two subjects were clearly incapacitated during the first 2Gz test under Compound A at 12,500 ft altitude. It is felt that the Gz intolerance resulted mainly from an adverse interactive effect of Compound A and altitude on vasomotor andor chronotropic mechanisms.