Chapter 6- Rescue and Emergency Procedures Rescue and Emergency Procedures 181 stages, signals to the buddy, then looks toward the surface, extends a hand overhead, uses the buoyancy compensator inflator valve to vent excess air, and breathes normally while swimming directly to the surface at a normal ascent rate. Redundant systems are common among divers in highly technical specialties such as cave, ice, deep, and wreck diving. These specialties all require additional training. A very small redundant scuba system that holds about 27 to 57 L (1 to 2 cubic feet) of air also is available (figure 6-1). While very compact, it may not contain enough air to make a slow ascent and safety stop in an emergency. Emergency Swimming Ascent An out-of-air diver still has air in his or her lungs. During ascent, when the diver reaches relatively shallow depths, that volume of air will increase, and that air is most likely sufficient for the time that it will take to reach the surface. The diver retains the second stage in the mouth, looks toward the surface, extends a hand overhead, uses the buoyancy compensator valve to exhaust excess air, and swims directly to the surface as close to the normal ascent rate as possible while exhaling very gently all the way. Since scuba delivers air at ambient pressure, additional air may become available to the outof air diver as ambient pressure decreases during ascent. Attempts to inhale should be made because additional air may be available, and these attempts may also help to open the smallest of airways within the lungs, thus preventing possible lung over-expansion injuries. With training, a relaxed diver can execute the emergency swimming ascent from surprising depths (figure 6-2). A neutrally buoyant diver becomes more buoyant upon ascending a short distance, thereby reducing the effort required to swim to the surface. Indeed, keeping the rate of ascent slow enough is the more common problem. Exhalation should not be forced. In a desperate situation where the diver feels that he or she will not make it to the surface, the weight belt should be dropped. This will then become a buoyant ascent, which is described herein. Buoyancy Compensator Breathing The air contained in your buoyancy compensator is breathable provided you have not activated a CO2 cartridge. Because of the risk of severe lung infections, NAUI does not recommend training in this technique. It is described here purely for academic discussion purposes. To access this air, you must first clear any water from the inflator hose. Blow into the inflator mouthpiece while rolling from a face-down position away from the inflator hose over to your back. Look toward the surface, extend a hand overhead, and exhale into and inhale from the mouthpiece while holding the valve open. Breathe continuously, allowing excess air to escape from your mouth or nose as FIGURE 6-2. EMERGENCY SWIMMING ASCENT (ESA)
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