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Venous gas emboli and complement activation after deep repetitive air diving
J Zhang1, C E Fife, M S Currie
1Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.
Undersea Biomedical Research
|July 1, 1991
Summary
Repetitive diving activates complement, a key immune response, by increasing red blood cell-bound C3d. This immune activation occurred after a second dive, not a single dive, in healthy divers.
Area of Science:
- Physiology
- Immunology
- Marine Biology
Background:
- Decompression sickness (DCS) is linked to complement activity, but how gas bubbles affect this immune response remains unclear.
- Understanding intravascular complement activation is crucial for assessing DCS risk and developing preventative strategies.
Purpose of the Study:
- To investigate intravascular complement activation following repetitive air diving in humans.
- To measure red blood cell-bound C3d as an indicator of complement activation after diving.
Main Methods:
- Healthy subjects underwent single or repetitive air dives to 170 feet of seawater.
- Red blood cell-bound C3d levels were measured predive and postdive.
- Doppler monitoring assessed venous gas emboli, and complement sensitivity to bubbles was evaluated.
Main Results:
- No cases of DCS were reported in 39 dives.
- Intravascular complement activation, indicated by increased RBC-bound C3d, occurred after repetitive dives but not after a single dive (P < 0.05).
- The severity of gas bubbles (maximum bubble grade) did not correlate with the level of complement activation.
Conclusions:
- Repetitive air diving, even without causing DCS, triggers intravascular complement activation.
- The complement system's response to diving may be more sensitive to repeated bubble exposure than to a single exposure.
- Further research is needed to clarify the role of complement activation in DCS pathophysiology.