EFFECTS OF MODERATE ALTITUDE ON PATIENTS WITH PULMONARY AND CARDIAC IMPAIRMENT.

Twenty ambulatory patients with severe chronic pulmonary disease and 24 with severe heart disease were exposed in an altitude chamber to a simulated altitude of 8000 feet such as might exist in pressurized aircraft. Eight of the patients in the pulmonary group experienced undersirable reactions related to hypoxia, hypoventilation, inability to hyperventilate and expansion of gases. None of the 24 patients with cardiac disease experienced this same difficulty and all tolerated the procedure well. The ability to tolerate the stress of moderate altitude is related more to ventilatory efficiency and the maintenance of adequate oxygen saturation than to cardiovascular factors. It is recommended that a thorough evaluation of the cardio-pulmonary patient by clinical and physiological tests be made before exposure to altitude. When severe impairment is demonstrated, the subject may still be able to tolerate moderate altitudes if appropriate measures are provided to cope with the altered physiologic conditions.