Tolerance of Beta Blocked Hypertensives during Orthostatic and Altitude Stresses

To evaluate the effects of orthostatic, attitude, and pharmacologic stresses upon civil aviation-specific performance, a double-blind, randomized, crossover trial of atenolol, 100mg, was designed and executed. Hypertensive mates and females qualifying for the FAA class 3 certificate with mean age of 34 were studied during simulated attitude exposure to 12,500 ft, orthostatic stress, and moderate exercise. Seated Lower body negative pressure to -40 mmHg supplied orthostatic stress simulating +2G vertical acceleration. A total of 160 Lower body negative pressure tests were performed, 80 at ground and 80 at altitude. Beta-blockade caused a modest impairment in orthostatic tolerance. Five of the 80 Lower body negative pressure runs at ground level were marked by intolerance, and all of those responses were in beta-blocked subjects. of the 80 attitude runs, 30 were terminated for intolerance, of which 18 included beta- blockade. These findings had a Chi-square significance value of P < .05. The effect of attitude was significant at P < .01. In a modest exercise protocol (100 watts for 3 minutes) meant to be no more stressful than the exertional requirements of piloting an aircraft during adverse conditions, neither beta- blockade or altitude appeared to Limit performance. Quantitative performance on a computerized cognitive battery clearly demonstrated impaired performance during Lower body negative pressure stress at altitude. The degree of impairment was significant compared to a learning curve response at the P < .001 level. The degree of impairment was similar for placebo treated and beta-blocked subjects.