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Changes in PUFA and eicosanoid metabolism during/after apnea diving: a prospective single-center study.

Background
The popularity of apneic diving is continually growing. As apnea diving substantially burdens the cardiovascular system, special focus is warranted. Regarding inflammation processes and associated inflammatory-related diseases (e.g., cardiovascular diseases), eicosanoids play an important role. This study aims to investigate polyunsaturated fatty acids (PUFAs) and eicosanoids in voluntary apnea divers, and so to further improve understanding of pathophysiological processes focusing on proinflammatory effects of temporarily hypercapnic hypoxia..


Methods
The concentration of PUFAs and eicosanoids were investigated in EDTA plasma in apnea divers (n=10) before and immediately after apnea, 0.5 hour and four hours later, applying liquid chromatography-tandem mass spectrometry (LC-MS/MS).


Results
Mean age was 41±10 years, and divers performed a mean breath-hold time of 317±111 seconds. PUFAs, eicosanoids and related lipids could be classified in four different kinetical reaction groups following apnea. The first group (e.g., Ω-6 and Ω-3-PUFAs) showed an immediate concentration increase followed by a decrease below baseline four hours after apnea. The second group (e.g., thromboxane B2) showed a slower increase, with its maximum concentration 0.5 hour post-apnea followed by a decrease four hours post-apnea. Group 3 (9- and 13-hydroxyoctadecadienoic acid) is characterized by two concentration increase peaks directly after apnea and four hours afterward compared to baseline. Group 4 (e.g., prostaglandin D2) shows no clear response.


Conclusion
Changes in the PUFA metabolism after even a single apnea revealed different kinetics of pro- and anti-inflammatory regulations and changes for oxidative stress levels. Due to the importance of these mediators, apnea diving should be evaluated carefully and be performed only with great caution against the background of cardiovascular diseases and inflammation processes.