MEASUREMENT OF CARDIOPULMONARY PERFORMANCE DURING ACUTE EXPOSURE TO A 2440-M EQUIVALENT ATMOSPHERE

  • 1 January 1982
    • journal article
    • research article
    • Vol. 53  (7) , 639-642
Abstract
Each of 20 subjects was given 2 Bruce Protocol symptom-limited maximum treadmill stress tests breathing sea-level compressed air (20.9% O2) for 1 test and a 2440-m equivalent (15.5% O2) for the other. Subjects ranged from 18-38 yr of age; 15 were male and 5 female. Half of the population was tested first on the sea-level air, the other half on the altitude mixture. Real time measurements included heart rate, blood pressure, exercise time, O2 consumption VO2, CO2 production, respiratory rate and volume and several other derived parameters. A significant difference existed between measured VO2 max (P < 0.002) and exercise time (P < 0.004) for the 2 conditions. Mean differences were 8.3% and 6.7%, respectively. No significant differences were observed in heart rate or the recovery time to a respiratory quotient of < 1. Hb saturation, as measured by an ear oximeter, average 95% for sea-level and 91% for the 2440-m equivalent gases. These results support a 2440-m equivalent contingency atmosphere in the NASA Space Shuttle prior to donning a low pressure suit for the purpose of reducing N2 washout times.

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