DIVING DECOMPRESSION FAILS TO ACTIVATE COMPLEMENT

The present study evaluated complement activation during decompression after air dives in a hyperbaric chamber. Intravascular bubbles were q uantified by Doppler ultrasound scoring. Eighteen subjects completed 9 2 dives, of which 74 produced bubbles. Complement activation was asses sed by plasma C3a des Arg and red-cell-bound C3d before and after each dive. These parameters of in vivo complement activation failed to sho w significant activation. In vitro complement activation susceptibilit y tests on pre-dive sera were performed to explore their association w ith in vivo complement activation and intravascular bubbles. Such test s failed to identify a distinct complement-sensitive group and did not correlate with in vivo complement activation during the dives and/or intravascular bubble appearance. Two subjects developed decompression sickness but were not different from the rest of the group regarding i n vitro complement sensitivity or complement activation during dives.