Free fatty acids do not influence venous gas embolism in divers

Decompression sickness is caused by bubbles of inert gas predominantly found in the venous circulation. Bubbles may exist longer when covered by a surfactant layer reducing surface tension. Surfactant candidates, based on 3D-structure and availability, are long-chain fatty acids (FFAs). It is hypothesized that sufficient molecular dissolved FFA (dFFA) result in higher bubble grades (BGs). Participating divers (52) either had a fat-rich or a fat-poor breakfast. After a dry dive simulation (21 msw/40 min), BGs were determined at 40, 80, 120, and 160 min after surfacing by the precordial Doppler method. The four individual scores were transformed to the Kisman Integrated Severity Score (KISS). Kiss was not affected by meal fat content, and KISS and dFFA (calculated) were not associated, even though the fat-rich group had 3.5 times more dFFA. A paired approach (11 subjects exposed to fat-rich and fat-poor meals) yielded the same results. The measured FFA (albumin bound) was present in abundance, yet the long-chain dFFA concentration was probably too low (nM range) to form a surfactant monolayer, as follows from micelle theory. Bubble scores are not associated with dFFAs. Theoretically it is questionable whether long-chain dFFAs could form post-dive monolayers. It remains unclear which substance forms the surfactant layer around bubbles