Inflammatory Biomarkers Comparison Between Breath-Hold and SCUBA Divers

Background: The pathogenesis of decompression sickness is multifactorial, involving bubbles and oxidative stress that lead to inflammatory responses. Ex vivo evidence indicates that oxidative stress occurs rapidly while at depth, prompting our hypothesis that biomarkers of inflammation would be similar between 12 subjects performing breath-hold (BH) dives lasting 1 to 2 minutes and 10 subjects performing Self-contained underwater breathing apparatus (SCUBA) (S) dives lasting 16 to 40 minutes. Methods: Consenting experienced diver research subjects traversed depths of 15 and 40 meters of seawater (msw). Laboratory measures were conducted on blood obtained prior to and following each dive. Vascular gas emboli were assessed by cardiac ultrasound. Results: Post-dive, there were significant elevations (p < 0.05, two-way within-subject ANOVA) in all divers for circulating levels of microparticles measured by flow cytometry, and post-diving microparticles (MPs) from S and BH divers exhibited equal propensity for activating human neutrophils. There also were significant elevations of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-6, IL-10 and vascular cell adhesion molecule measured by enzyme-linked immunosorbent assays, and reactive oxygen species from electron paramagnetic resonance measurements. Mean fold-elevations for 15 msw BH dives were 1.51 ± 0.34 (standard deviation (SD)) and for S dives, 1.81 ± 0.67 (no significant difference, NS). For 40 msw dives, fold-elevation values for BH were 2.21 ± 0.81 and for S, 2.21 ± 0.86 (NS). For reactive oxygen species (ROS), TNF-α and IL-1β, some values were greater for S versus BH dives. Cardiac bubbles were rare for all divers with no significant difference between groups. Conclusions: We conclude that even among BH divers, oxidative stress and inflammatory responses to pressure occur rapidly. Some biomarkers are greater among S divers, which may reflect longer dive durations and higher systemic oxygenation.