Alternative Protocol for In-Water Recompression by Dr Carl Edmonds

This is an alternative Protocol by Dr Carl Edmonds of the Australian Navy School of Underwater Medicine for treatment of DCS in water at a shallower depth, as suggested by John Lippmann.

In-water Oxygen Treatment Procedures Oxygen should be supplied at maximum depth of 9 msw (30 fsw), from a surface supply system. The ascent is commenced after 30 minutes in mild cases, or 60 minutes in severe cases, if significant improvement has occurred. These times may be extended for another 30 minutes, if there has been no improvement.

The ascent is at the rate of 12 minutes per metre (4 minutes/foot). A diver attendant should always be present, and the ascent controlled by the surface tenders. The duration of the tables range from 2 hours 36 minutes or 3 hours 6 minutes depending on the treatment options used.

After surfacing the patient should be given periods of oxygen breathing, interspersed with air breathing, usually on a one hour on, one hour off, basis, with respiratory volume measurements and chest X-ray examination if possible. The treatment can be repeated twice daily, if needed.

The equipment required for this treatment is similar to that used in a surface supplied oxygen decompression system with some important differences. In the case of an in-water treatment, a G size cylinder (220 cubic feet or 7000 litres) of medical oxygen is probably adequate though specific requirements can easily be calculated. This is usually available form local gas supply companies or hospitals, although in some cases industrial oxygen has been used.

For a diver at rest, breathing this volume of oxygen at a depth varying between 9 meters (30 feet) and the surface is usually insufficient to produce either neurological (CNS) or respiratory oxygen.

Note that all equipment used with pure oxygen must be rated for oxygen service. Also, whenever oxygen is given, the cylinder should be turned on slowly and the flow commenced, before it is given to patients or divers. A 2-stage regulator, set at 550 kPa (80 psi) is fitted with a safety valve, and connects with 12 metres (40 feet) of supply hose. This allows for 9 metres depth, 2 metres from the surface of the water to the cylinder, and 1 metre around the diver. A non-return valve is attached between the supply line and the full face mask.

The full face mask is critical as it enables the system to be used with a semiconscious or unwell patient. It reduces the risk of aspiration of sea water, allows the patient to speak to his attendants, and also permits vomiting to occur without obstructing the respiratory gas supply. The supply line is marked in distances of 1 metre from the surface to the diver, and is tucked under the weight belt, between the diver’s legs, or is attached to a harness. The diver must be weighted to prevent drifting upwards in an arc by the current.

In-water air treatment of DCS is not to be undertaken lightly, however, in the absence of a recompression chamber or other options, it may be the only treatment available to prevent death or severe disability.


Dr.Carl Edmonds is a founding member of the South Pacific Underwater Medicine Society (SPUMS).

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2 thoughts on “Alternative Protocol for In-Water Recompression by Dr Carl Edmonds”

  1. Great article, In the water O2 deco has been used for sport diving since 1980, Captain Billy Deans started using In water O2 while diving the wreck of the USS Wilkes Barrier, max depth 240 fsw. The first time I was aware of in the water use of O2 was in 1969 when a diver salvaging the local wrecks SS Oregon and others for their brass & bronze he set up a 55 gallon barrel weighted and submerged it at 20 fsw with and surface supplied O2 regulator for the divers to decompress on, very cutting edge. In 1980, I was operating the Wahoo out of Long Island and running dives to the Andrea Doria and we moved out of the dark ages of the NO NO to O2 use on dive boats, O 2 was frowned on by all the training agencies and the Coast Guard, on the Wahoo we set up an O2 system using a 300 cf cylinder with a high output regulator with a Y connector supplying two different hoses and regulator, the hoses were 50 foot long so they could use the regulators around the boat and out to the swim platform incase a diver surfaced with a problem and needed O2 boarding the boat with the tank in the cabin it gave us a wide range of area to supply the O2 too. At this time we had no set this up for surface supplied in-water deco it was used only aboard the boat and not used the O2 system for actual in water decompression, that came about in 1985 when Captain Billy Deans brought a group of divers for an Andrea Doria expedition and brought his surface supplies in-water system, we used a 300 cf O2 bottle and high performance regulator with twin regulators and weighted and submerged the regulators to 30 fsw for the divers to use before exiting the water after each dive. After seeing the in-water system work so well and easy to deploy and recover and the benefits of removing some n2 from the divers, I built the Wahoo’s system for my deep diving expeditions. The system needed a lot of thought, when operating deep offshore dives for 24 divers the amount of O2 gas needed would be several 300 cfm cylinders and including a manifold to connect the bottles as it was used and to have a large enough O2 gas to get any diver back to shore if they had a problem. The in-water surface supplies system we used was not to encourage divers to modify their dives or encourage the divers to change their dive profile or extend their dives but to be used to help degas from their planned dive or in the event of a malfunction incident during their planned dive. The surface supplied O2 system was not used for local wreck dives, it was used for the offshore multi day deep wreck dives. There are three basic types of O2, used Welding, Medical and Aviation O2. in many states to use medical O2 you need a prescription for a doctor, welding gas is frowned on and the way the bottle are handled and not always clean, the opens the use of Aviation gas .

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