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Updated: May 10, 2026
11:56
Training Rats to Voluntarily Dive Underwater: Investigations of the Mammalian Diving Response
Published on: November 12, 2014
ECG changes during the experimental human dive HYDRA 10 (71 atm/7,200 kPa)
V Lafay1, P Barthelemy, B Comet
1Laboratoire de Physiopathologie Respiratoire, URA 1630 CNRS, Faculté de Médecine, Marseille, France.
Summary
Electrocardiogram (ECG) changes in divers during a deep saturation dive showed initial bradycardia and altered P and T vector angles. Decompression led to reduced ECG voltage, possibly due to microbubble formation.
Area of Science:
- Cardiology
- Hyperbaric Medicine
- Physiology
Background:
- Deep saturation diving presents unique physiological challenges.
- Understanding the cardiac response to extreme pressure and gas mixtures is crucial for diver safety.
Purpose of the Study:
- To analyze electrocardiogram (ECG) changes in human divers during a 71 atm saturation dive.
- To investigate the effects of hyperbaric conditions, including hydrogen and helium-oxygen gas mixtures, on cardiac electrical activity.
Main Methods:
- Electrocardiogram (ECG) monitoring of three human divers during the COMEX HYDRA 10 experiment.
- Analysis of ECG parameters including intervals, segments, axes, and vector angles under extreme pressure and gas composition.
Main Results:
- Significant bradycardia observed during compression, which adapted over time.
- Rightward shifts in P and T vector angles correlated with time and gas density, respectively.
- A marked decrease in ECG voltage during decompression, potentially due to microbubble-induced impedance changes.
Conclusions:
- Cardiac repolarization modifications during compression may relate to increased intrathoracic pressure from dense gas breathing.
- Decompression-induced voltage reduction suggests microbubble interference with ECG signal amplitude.
- ECG monitoring provides insights into cardiac adaptation and potential physiological disruptions during extreme hyperbaric exposures.
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