Medical hazards of air travel.
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Biomedical subjects
Publications and source records attributed to I D Rennie.
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The severity of acute mountain sickness (AMS) was investigated in healthy volunteers, airlifted to high altitude (5,360 m). Blood gases were measured at 2,990 m and 5,360 m. Symptoms of AMS were found in all subjects, but ranged from malaise to vomiting with intractable headache. The clinical severity of AMS was directly related to the arterial PCO2 and inversely to pH, but unrelated to the PO2 on arrival at high altitude. However, PO2 fell and was lowest 48 h after arrival at high altitude in those subjects with the most severe AMS. These were the only subjects to show an increase in the alveolar-arterial PO2 difference and in the venous admixture ratio during the first 48 h. These abnormalities in gas exchange, which developed in the subjects with the most marked cerebral symptoms, suggest that the manifestations of cerebral and pulmonary dysfunction at altitude develop simultaneously, a finding that suggests coexisting cerebral and pulmonary edema.
Hormone, electrolyte, and body fluid compartment changes were studied in subjects who either spent time at 10,000 ft before flying to 17,500 ft or were premedicated with acetazolamide and flown directly to 17,500 ft. In the former group, at 10,000 ft, renin and aldosterone were not different from control. Cortisol increased significantly from 9.8 to 19.5 mug/100 ml on the third day. At 17,500 ft, renin, aldosterone and cortisol were significantly elevated on day 3 but had returned to control levels by day 5. Sodium and potassium excretion was significantly reduced at both altitudes. Total body water, extracellular and plasma volume were reduced (P less than 0.05) at 17,500 ft. Subjects pretreated with acetazolamide and flown directly to 17,500 ft had significant increases (P less than 0.001) in plasma renin, aldosterone, and cortisol levels during the first 4 days at altitude. On day 1 there was a decrease of 45% in sodium and 38% in potassium excretion. On day 4 there was a decrease of 63% and 51%, respectively. These changes are not associated with the premedication. The initial changes may reflect the immediate response to stress and alkalosis followed by a return to control levels as the body adapts to altitude.
Distinct glomerular ultrastructural lesions in the form of nodular subepithelial and intramembranous, as well as discrete and band-like subendothelial deposits are described in a patient suffering from mixed IgG-IgM essential cyoglobulinemic glomerulonephritis. It is suggested that the deposits may represent immune complexes which are belived to play a central role in the pathogenesis of the glomerulonephritis.
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