Prophylactic Statins as a Possible Method to Decrease Bubble Formation in Diving

Duplessis CA, Fothergill D, Schwaller D, Hughes L, Gertner J. Prophylactic statins as a possible method to decrease bubble formation in diving. Aviat Space Environ Med 2007; 78:430–434.



Introduction: Nitric oxide (NO) may decrease bubble formation in diving. Statin medications are attractive potential options to increase NO. Statins exhibit a proven safety profile, and possess a myriad of pleiotropic properties improving vascular endothelial function. Additionally, statin-mediated lipid reduction may reduce bubble generation via alterations in plasma surface tension. We investigated the efficacy of atorvastatin as a pharmacological intervention to reduce the risk of bubble formation after diving, a surrogate for decompression sickness (DCS). Methods: There were 16 trained military divers who completed a provacative hyperbaric chamber dive protocol after taking either 80-mg of atorvastatin or placebo for 4 d. Subjects completed the alternate medication regimen no sooner than 2 wk. After each dive, subjects were subjected to precordial trans-thoracic echocardiographic exams via standardized protocols. Bubbles were graded via a non-parametric, ordinal grading system and statistically analyzed via Wilcoxon signed-rank tests. Results: We found no within subject differences for the maximum bubble grade scores (z = 0.00, p = 1.00, n = 16). Low-density lipoprotein (LDL), and total cholesterol (TC) levels decreased significantly (107.6 ± 26.2 to 79.3 ± 21.9 mg · dl⁻¹ and 175 ± 20.9 to 147 ± 22.4 mg · dl⁻¹, respectively) 1–2 wk post statin administration. Age, bioelectrical impedance (BEI), TC, LDL, potassium, and calcium demonstrated positive correlations to placebo bubble grades. Discussion: Prophylactic 80-mg atorvastatin administration for 4 d failed to reduce the number of intravascular bubbles observed following a 60-ft, 80-min dry chamber dive despite significant acute reductions in lipid levels. Several hypotheses may explain why statins failed to decrease bubble volume: 1) differential influence of statins on the venous vs. arterial vasculature; 2) failure to elicit an improvement in endothelial function and, therefore, the hypothesized endothelial conditioning in younger patients possessing normal baseline; and 3) the ordinal grading system encompassing a substantial variation in bubble volume (bubbles · cm⁻²).