Nitrogen washout during a fatty meal while breathing nitrogen-free gas at sea level

Introduction: The reasons for wide variability in the incidence of decompression sickness (DCS) are not well known, but diet may play a role. The hypothesis of the present study was that raising plasma triglycerides via a high-fat meal would increase the rate of nitrogen washout and, therefore, might be a useful adjunct when denitrogenation is used to reduce the likelihood of DCS in diving and exposure to altitude. Methods: Nitrogen elimination was measured for 125 min in 10 subjects by gas chromatography while they breathed a normoxic argon-oxygen mixture at sea level. Measurements were performed on separate days after high-fat and control, low-fat meals. Results: The high-fat meal increased blood triglycerides by 236 ± 86% while there was no significant change after the control meal. Despite causing a significant increase in cardiac output (21.6 ± 13.8%), there was no difference in nitrogen elimination after high-fat (817.4 ± 233.1 ml) vs. control (828.3 ± 180.5 ml). Discussion: These data suggest that raising blood triglycerides via a high-fat meal does not affect the rate of whole-body nitrogen elimination. The lack of effect of the increase in cardiac output may be due to an increased blood flow to the gastrointestinal tract being negated by decreased blood flow in other vascular beds.