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Prioritized Brain Circulation During Ergometer Cycling with Apnea and Face Immersion in Ice-Cold Water: A Case Report
Lars J Bjertnaes1,2, Anton Hauge3, Marianne Thoresen3,4
1Anesthesia and Critical Care Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, N-9037, Norway.
International Medical Case Reports Journal
|October 4, 2021
Summary
Cold water immersion and apnea prioritize blood flow to the brain, mimicking marine mammals. This physiological response may enhance brain oxygenation and cooling during emergencies.
Area of Science:
- Physiology
- Human diving response
- Cardiovascular regulation
Background:
- Hypothermia from drowning/avalanche may aid resuscitation by reducing metabolic demand.
- Investigated if marine mammal-like oxygen-sparing mechanisms improve human cerebral oxygenation during airway blockade.
Observation:
- Hemodynamic changes were studied during ergometer cycling with apnea and face immersion (AFI) in cold water.
- During AFI, heart rate (HR) decreased 58%, radial artery average blood velocity (ABV) fell 85%, and vertebral artery ABV rose 67%.
Findings:
- Breath-holding alone during cycling mimicked radial artery ABV changes.
- Face immersion with snorkel breathing maintained HR but caused transient radial artery ABV decrease.
- Prioritized cerebral circulation during AFI in cold water was confirmed.
Implications:
- Hypothesized that prioritized cerebral circulation improves brain oxygenation via increased blood flow and potentially faster brain cooling.
- Findings may inform resuscitation strategies for drowning and avalanche victims.
- Supports the existence of selective brain cooling mechanisms, as seen in diving seals.
