Excursions to the Surface as a Component of Emergency Decompression from Air or Nitrox Saturation Exposures

Present equipment capability precludes a pressurized transfer of personnel rescued from a pressurized, distressed submarine using either the Submarine Rescue Chamber (SRC) or the Deep Submergence Rescue Vehicle (DSRV). An unpressurized transfer risks potentially lethal decompression sickness. Experiments were conducted at this laboratory to determine the period of time available for such an unpressurized transfer to be conducted safely, with a minimal risk of decompression disease. Eighteen active duty and reserve Navy divers were saturated on air at each of 3 pressures; 20 psig (45 fswg), 24.5 psig (55 fswg) and 29 psig (65 fswg). Direct release of the pressure was followed by a surface or unpressurized interval of 30, 17 and 10 minutes, respectively, prior to recompression. The data indicate that this procedure is safe, and carries less than a 10% risk of decompression sickness for the intervals examined. Furthermore, the data would predict that excursions to the surface from air or nitrox saturation exposures are safe from depths much greater than previously predicted.