Diver rescue

Recommended procedures for recovering a disabled or unresponsive scuba diver to the surface have varied over time, and to some extent depend on circumstances and the equipment in use.

Nevertheless, recreational divers are usually advised by their training agencies to dive as buddy pairs so they can assist each other if one gets into difficulty.

The effort and difficulty of a rescue varies widely and depends on many factors such as the nature of the problem, the underwater conditions and the type and depth of the dive site.

A complex and high-risk rescue would be to locate, free and bring to the surface a lost diver who is trapped underwater in an enclosed space such as a shipwreck or cave with limited breathing gas supplies.

This is common in scuba accidents, where separation of the diving team members is often the first indication of a potential problem, and many emergencies are first recognised when a diver fails to surface at the expected time.

Even when open circuit equipment is used it may be difficult to see the bubbles due to surface conditions of wind, waves and spray, fog, or darkness.

[3][4] A standard precaution when entering enclosed spaces is to use a guideline to mark the exit route, which may be needed after the diver's fins, wash, and bubbles dislodge silt and loose overhead materials such as rust which can reduce underwater visibility to near zero.

At the end of a deep dive they will need more gas to breathe during the longer ascent to the surface and during any decompression stops.

Another entrapment risk occurs when divers try to squeeze through small gaps where they or their equipment can become wedged or caught.

Old ferrous shipwrecks can be structurally unstable; they may retain their shape but have lost their strength through corrosion and therefore have components or cargos that have high potential energy due to gravity, and may collapse without warning.

Lifting bags can be used to help move heavy objects underwater, but are not carried as standard equipment by most divers.

A closed bell may be partly flooded to aid lifting the casualty through the bottom lock opening, after which it will be blown down with breathing gas to remove the water.

If there is a swell running, the line tension will decrease after each wave passes, at which time winding in will be easier.

[2] In this situation and if the rescuer needs to do decompression stops, the rescuer has a dilemma; take the casualty to the surface and increase the risk or severity of decompression sickness, including irreversible injuries or death, or do the stops and risk leaving the casualty to die by asphyxiation or drowning.

[2] Expanding gases will generally pass passively out of the airway during rescue from depth, and pulmonary barotrauma is rare.

[8] The US Navy Diving Manual Revision 6 Volume 4 section 17.11.1.4 recommends the following procedure for managing a convulsing casualty at depth.

Furthermore, the main goal while the diver is in the water is to prevent drowning, and secondarily ensure that the airway is open after the convulsion stops by keeping the neck extended.

The Diving Committee of the Undersea and Hyperbaric Medical Society reviewed the procedures for rescuing a submerged unresponsive compressed-gas diver and published their recommendations in 2012.

[2] The Medical Panel of the NATO Underwater Diving Working Group (UDWG) examined the procedure for management of a convulsing diver using a half-mask and separate mouthpiece at depth.

They concluded that the available evidence to support delaying surfacing until the clonic phase of oxygen toxicity convulsions dissipated was insufficient, that the probability of complete airway obstruction during a seizure was low, and that the survivability of pulmonary barotrauma was relatively high.

Often with a small group of rescuers the emergency services can only be contacted after the highest priority job of getting the casualty is out of the water has taken place.

[3] If the casualty is not breathing, it is possible to sustain respiration or even restart it by artificial ventilation (AV) at the surface of the water.

Ropes and webbing can be very useful, but some precautions are need: "Purbuckling" (or parbuckling) can be used to lift a casualty from the water up a vertical surface such as a high sided boat, pontoon or a jetty.

The loop of rope is positioned so that in passes outside the arms between the shoulder and elbow and around the outside of the legs between the knee and the hip.

[10] In other parts of the world and particularly in remote locations, it may be difficult to quickly arrange reliable emergency medical transport and treatment; good insurance and self-reliance are needed.

This may in some cases involve sending an unresponsive victim to the surface by making them positively buoyant while the rescuer completes their decompression.

Saturation divers cannot be decompressed to surface at acceptable risk, and must remain under pressure during first aid and further medical treatment.

This means that they must transfer from whatever environment they occupy at the time of the emergency, to a place of safety at effectively the same pressure at all stages.

Rescuers should not take unacceptable risks; any rescuers who become casualties themselves may jeopardise the rescue of the original casualty particularly as many of the emergency resources available at dive site, such as rescue manpower, first aid oxygen, underwater time and gas are generally in short supply.

The level and quality of training and required skill for certification may vary depending on the jurisdiction and relevant code of practice.