Any technical diver will agree that there are certain risks involved in the sport of scuba diving, but will add that it is even more dangerous when doing technical diving. The deeper we go the higher the risks of decompression sickness (DCS) and likelihood of barotrauma. Any diver should also agree that early oxygen therapy and evacuation to a hyperbaric facility (recommended by DAN) is necessary if DCS symptoms are experienced after a dive.
As a paramedic and technical diver I am always concerned with the treatment and evacuation options available if something should happen to a fellow diver or myself. My concern is mostly brought on due to the type of locations that we travel to in order to do our exciting sport. The remoteness of certain technical dive locations in South Africa can make it difficult to provide appropriate emergency care and fast evacuation transport. It is thus challenging to have a medical plan that is safe, efficient and that addresses the recompression needs of a patient.
Over the past few decades, in-water recompression (IWR), has emerged as a field treatment (at the scene) that is used by technical divers in remote locations. IWR is used as an alternative or extra method to recompress a diver with DCS. This practice is, however, seen as extremely controversial by some in the diving community and is heavily criticised by dive medical experts all over the world. So be warned if you try to use IWR as a ‘curveball, at a cocktail party!
IWR is defined as the practice of treating divers suffering from decompression sickness (DCS) by recompression underwater after the onset of DCS systems. Others add that the recompression is immediate and that it occurs in remote locations where no recompression chambers are available.
In practice there are three well-known methods of IWR that have been published, namely: the Australian method, the US Navy method and the Hawaiian method. There may also be others that have been developed for a specific purpose or region. The most commonly used is the Australian method which was first published in 1976. It is described as the surface supply of 100% oxygen to a diver with a full face mask at 9m. According to the symptoms of the diver he would spend between 30-90 minutes at 9m and would thereafter ascend at a rate of 1m every 12 minutes.
The US Navy method is described as being used when 100% oxygen rebreathers (with full face mask) are available and only in an emergency. This method was developed for military use and does not seem to be used by civilians. It is suggested that the diver breathes 100% oxygen at 9m for 60 minutes for type 1 DCS (pain only) or 90 minutes for type 2 DCS (neurological symptoms). This will be followed by an additional 60 minutes at 6m and again at 3m.
The Hawaiian method is a modification of the Australian method. The diver breathes air during a 10 minute descent to a depth of 9m deeper than the depth at which symptoms disappear. The maximum depth is 50m after which the diver will return from this “air spike” to 9m to breathe 100% oxygen for at least an hour.
The basic requirements of all the IWR methods are large amounts of oxygen whicht must be delivered with a full face mask. A tender diver is needed to monitor the diver all the time and a heavily weighted line for reference of depth is required. Some form of communication between the diver, tender and the surface support crew is also necessary.
In theory there are several dangers and risk factors associated with attempting IWR. There is a possibility that more nitrogen will be added to the already saturated tissues (if air is breathed) and thus worsening the DCS. There is also the risk of drowning due to DCS and also the time of exposure to cold water that can lead to hypothermia. At sea, strong currents can cause exertion and certain marine life can pose a threat to diver safety. The weightlessness experienced by the diver underwater can also make it difficult to assess if the DCS symptoms are getting better or worse.
There are, however, two distinct advantages of IWR that cannot be overlooked. The first is that it allows for immediate recompression and the second is that an elevated partial pressure of oxygen is breathed if 100% oxygen is used. Several cases of IWR were published and of 527 reported cases, 87,7% had complete resolution of symptoms. 9,7% Improved symptoms that no further treatment was sought and in 2,7% of cases symptoms persisted after IWR and further treatment was sought at a recompression facility. In all of these cases air was used as the recompression gas. Although this evidence can seem very compelling for using IWR, it must be recognised that this data does not necessarily include all attempted IWR cases. It was discovered that most of the IWR cases were attempted with no formalised knowledge of published IWR methods – they were basically ‘winging it’ so to speak. It also came to light that no one visited a diving physician after their recompression therapy.
The Divers Alert Network (DAN) suggests that IWR should not be attempted at all. It must be remembered that the ideal would be to have a portable chamber than can allow recompression early at the scene without going back into the water. This can also allow you to do recompression while transporting the patient to a hyperbaric facility. The problem with this plan is the cost implication when compared to IWR.
It seems that the controversy surrounding IWR can only be lifted once certain issues are cleared up. Are there any circumstances under which IWR can be done safely? And if so, which method should be used? It is evident that IWR has worked for some and the establishment of a formal database for these cases will certainly be a step in the right direction.
IWR should never be a substitute or replacement for proper treatment in a recompression chamber. It is also not a ‘poor man’s’ cure for DCS. It is therefore imperative that a diving physician is visited after the treatment has occurred.
Sources: Pyle, R.L. & Youngblood, D.A. 1995. The case for in water recompression. Aquacorps, 11: 35 – 46 and Pyle, R.L. 1999. Keeping up with the times: Applications of technical diving practices for in-water recompression. Undersea and Hyperbaric Medical Society, 74 – 88.