[abstract] COMPLEMENT ACTIVATION DURING SATURATION DIVING: RELATIONSHIP TO DECOMPRESSION SICKNESS AND HPNS

Abstract

Levels of activated complement fragments C3a and C5a were measured on 11 U.S. Navy divers as they performed a 28 day saturation dive to a pressure equivalent of 1000 fsw (31 ATA). Seven samples (S) were taken from each diver: prior to the dive (Sl, S2), during the bottom phase (S3, S4), after an upward excursion to a depth equivalent of 849 fsw (S5), and after reaching the surface (S6, S7). Two divers developed symptoms consistent with high pressure nervous syndrome (HPNS) and three divers were treated for type I decompression sickness (DCS). One-way ANOVA with repeated measures and Neuman-Keuls post hoc testing showed a significant elevation in both C3a and C5a at S3 (p< 0.05) and S6 ( P < 0.001). We performed multiple Student t-tests with the Bonferroni correction (K =2) to test the hypotheses that C3a and C5a elevations at S3 were related to HPNS while those at S6 were related to decompression sickness. The divers with HPNS had C3a and C5a measurements at S3 that were not significantly different than the others (p>0.05). Divers with DCS had significantly higher (p<0.001) levels of C3a and C5a at S6. Their average C3a and C5a values at S6 were 1940 +/- 290 and 118 +/- 29, respectively, while divers not treated for DCS averaged 207 +/- 82 and 8.8 +/- 1.0. These results show that an increase in C3a and C5a levels which is unrelated to HPNS occurs during compression to deep depths and that elevations of these complement activation fragments correlates with the clinical diagnosis of type I DCS. (Supported by NMRDC Work Unit MRO4 101.001-1055)