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Updated: Jul 13, 2026
11:56
Training Rats to Voluntarily Dive Underwater: Investigations of the Mammalian Diving Response
Published on: November 12, 2014
Complement levels before and after dives with a high risk of DCS
P Nyquist1, R Ball, M J Sheridan
1Department of Neurology and Anesthesia/Critical Care, Cerebrovascular Division, Johns Hopkins School of Medicine, Rm 125 Phipps, 600 North Wolfe Street, Baltimore, Maryland 21287-6953, USA.
Summary
Complement activation, specifically C3a levels, correlated with decompression sickness (DCS) risk in divers. Higher DCS risk was associated with increased complement depletion after diving.
Area of Science:
- Hyperbaric Medicine
- Immunology
- Physiology
Background:
- Complement activation has been controversially linked to decompression sickness (DCS).
- Previous studies on complement activation in DCS have yielded conflicting results in both human and animal models.
Purpose of the Study:
- To investigate the relationship between complement activation and depletion after hyperbaric exposure.
- To determine if complement changes are associated with the risk of developing DCS.
Main Methods:
- Collected blood samples from 35 U.S. Navy diver volunteers (102 dives).
- Analyzed plasma for complement depletion (C3a levels) pre- and post-dive.
- Estimated DCS risk using a validated predictive model.
Main Results:
- Pre- and post-dive C3a concentrations showed a significant relationship with estimated DCS risk.
- Complement depletion (reduced C3a levels) increased proportionally with higher estimated DCS risk.
- The variation in predicted DCS explained by C3a was small (r² = 0.19).
Conclusions:
- Divers experienced a reduction in C3a levels following dives with a high estimated risk of DCS.
- This observed decomplementation appears to be dose-dependent on the estimated risk of DCS.
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