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Cardiac output during sleep at altitude
Aviation, Space, and Environmental Medicine
|July 1, 1977
Summary
Hypobaric hypoxia and sleep can reduce cardiac output (Q), potentially causing Acute Mountain Sickness (AMS). Reduced oxygen delivery during sleep may interact with altitude stress to trigger AMS symptoms.
Area of Science:
- Physiology
- Altitude Medicine
- Sleep Science
Background:
- Hypobaric hypoxia at high altitudes poses physiological challenges.
- Sleep patterns and cardiac function are altered at extreme environments.
- Acute Mountain Sickness (AMS) is a common condition at high altitudes.
Purpose of the Study:
- To investigate the impact of hypobaric hypoxia and sleep on cardiac output (Q).
- To explore the relationship between sleep, oxygen delivery, and the onset of AMS.
Main Methods:
- Cardiac output (Q) was measured using impedance cardiography.
- Electroencephalography (EEG) assessed sleep patterns.
- Subjects experienced varying altitudes within a hypobaric chamber.
Main Results:
- Cardiac output (Q) reached a nadir around 0500 hours, indicating reduced oxygen delivery.
- Sleep was generally normal, except during episodes of Acute Mountain Sickness (AMS).
- Observed synchronized sleep suggested the occurrence of sleep hypoventilation.
Conclusions:
- Hypobaric hypoxia and sleep hypoventilation may contribute to reduced oxygen delivery.
- The interaction of hypobaric hypoxia, sleep hypoventilation, and reduced oxygen delivery is implicated in AMS development.