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Why some people do not drown. Hypothermia versus the diving response.
1Department of Physiology and Pharmacology, Queen's Medical Centre, University of Nottingham, UK.
The Medical Journal of Australia
|November 2, 1992
Summary
Remarkable survival from prolonged near-drowning involves a combination of the diving response and hypothermia. This protective state of hypometabolism is key to understanding these rare survival cases.
Area of Science:
- Physiology
- Pathophysiology
- Clinical Medicine
Background:
- Debate exists on the roles of the diving response and hypothermia in near-drowning survival.
- Understanding these mechanisms is crucial for prolonged submersion cases.
Purpose of the Study:
- To review current knowledge on survival from prolonged near-drowning (1 hour or more).
- To evaluate the relative importance of the diving response and hypothermia.
Main Methods:
- Literature review of physiological, pathophysiological, and clinical papers.
- Focus on studies published between 1981 and 1991.
- Analysis of data related to the diving response, hypothermia, and near-drowning.
Main Results:
- Normothermic brains sustain irreversible damage after 10 minutes of asphyxia.
- Brain tissue resistance to hypoxia requires temperatures of 30°C or lower.
- The diving response, observed in some humans, prevents aspiration, conserves oxygen, and induces hypometabolism.
Conclusions:
- Survival from prolonged near-drowning depends on the interplay between the diving response and hypothermia.
- A protective hypometabolic state is achieved through this interaction.
- Further research may explore factors like alcohol's influence.