COMPLEMENT ACTIVATION IN DIVERS AFTER REPEATED AIR HELIOX DIVES AND ITS POSSIBLE RELEVANCE TO DCS/

Plasma levels of the anaphylatoxin C5a were measured in 19 divers perf orming repeated air dives. Blood samples were collected immediately be fore the first dive and 2 h after the first and the second or third di ve. Serum obtained at the same times was subjected to complement activ ation in vitro by air bubbles. Six divers developed symptoms of decomp ression sickness (DCS). Most intravascular bubbles were observed in di vers with the lowest plasma levels of C5a. Positive plasma levels of C 5a did not increase compared with predive levels, nor were postdive le vels significantly different after two or three dives compared with th e first dive. Repeated dives did not influence the amounts of C5a gene rated in vitro. Neither plasma levels of C5a nor C5a generated in vitr o were significantly different in divers who experienced symptoms of D CS vs. divers without symptoms of DCS. We conclude that plasma level o f C5a and measurement of C5a generation in vitro cannot be used to pre dict DCS.