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Acute Hypoxia and Related Symptoms on Mild Exertion at Simulated Altitudes Below 3048 m

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Smith AM. Acute hypoxia and related symptoms on mild exertion at simulated altitudes below 3048 m. Aviat Space Environ Med 2007; 78:979–84.



Introduction: Helicopter aircrew have reported features of hypoxia below 3048 m (10,000 ft). The aim of this study was to examine the effect of physical activity below 3048 m on the development of hypoxia.



Methods: Six subjects exercised at 30 W and 60 W for 4 min at sea level, 610 m, 2134 m, and 2743 m (2000 ft, 7000 ft, and 9000 ft).



Results: There was an abrupt decrease in Spo2 once physical activity was commenced. This was small at sea level (1%) and 610 m (2.2%), however, the Spo2 fell by 4.3% at 2134 m and 5.5% at 2743 m (to Spo2 88.1% and 85.7%, respectively). Spo2 returned to near-resting values within 3 min of stopping exercise. Symptoms of hypoxia were reported significantly more frequently during activity than rest at each of the altitudes.



Discussion: Helicopter aircrew should be aware that physical activity as low as 2134 m can produce hypoxemia and symptoms of hypoxia similar to that which would normally be expected in a person resting at approximately 3658–4572 m (12,000–15,000 ft).

Keywords: altitude; exercise; helicopter; hypoxia; rotary-wing

Document Type: Research Article

Affiliations: From the Armed Forces Aeromedical Centre, Dhahran, Saudi Arabia.

Publication date: 01 October 2007

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