Nitrogen partial pressures in man after decompression from simulated scuba dives

In five subjects arterial and central venous nitrogen partial pressures (PN2) were measured after decompression from a chamber dive following a decompression schedule for scuba diving. The simulated dives consisted of exposure at rest to air at 6 bar for 30 min. corresponding to a depth of 50 m. Afterwards the subjects were decompressed with decompression stops at 2.5, 2.2, 1.9, 1.6 and 1.3 bar with a total decompression time of 73 min. Immediately after decompression and every 40 min. until the 240th min. arterial and central venous blood samples were analyzed for PN2 using a manometric Van Slyke apparatus. Venous PN2 remained elevated until 160 min. after decompression indicating still incomplete nitrogen wash-out at least two hours after decompression had been accomplished. Bubble formation is discussed as a cause for prolonged nitrogen elimination. Our data confirm that nitrogen elimination is prolonged after decompression from simulated dives at rest.