Editing Decompression sickness (section)

===In-water recompression===
{{Main|In-water recompression}}

Recompression and hyperbaric oxygen administered in a recompression chamber is recognised as the definitive treatment for DCI, but when there is no readily available access to a suitable hyperbaric chamber, and if symptoms are significant or progressing, in-water recompression (IWR) with oxygen is a medically recognised option where a group of divers including the symptomatic diver already have relevant training and equipment that provides a sufficient understanding of the associated risks and allows the involved parties to collectively accept responsibility for a decision to proceed with IWR.<ref name="Mitchell et al 2018" /><ref name="Walker and Murphy-Lavoie" />

In-water recompression (IWR) or underwater oxygen treatment is the emergency treatment of decompression sickness by returning the diver underwater to help the gas bubbles in the tissues, which are causing the symptoms, to resolve. It is a procedure that exposes the diver to significant risk which should be compared with the risk associated with the other available options. Some authorities recommend that it is only to be used when the time to [[Medical evacuation|travel]] to the nearest [[recompression chamber]] is too long to save the victim's life, others take a more pragmatic approach, and accept that in some circumstances IWR is the best available option.<ref name=uhms /><ref name=Pyle /> The risks may not be justified for case of mild symptoms likely to resolve spontaneously, or for cases where the diver is likely to be unsafe in the water, but in-water recompression may be justified in cases where severe outcomes are likely, if conducted by a competent and suitably equipped team.<ref name="Doolette and Mitchell 2018" />

Carrying out in-water recompression when there is a nearby recompression chamber or without suitable equipment and training is never a desirable option.<ref name=uhms/><ref name=Pyle/> The risk of the procedure is due to the diver suffering from DCS being seriously ill and may become [[paralysed]], [[Unconsciousness|unconscious]] or [[Apnea|stop breathing]] while under water. Any one of these events is likely to result in the diver [[drowning]] or asphyxiating or suffering further injury during a subsequent rescue to the surface. This risk can be reduced by improving airway security by using surface supplied gas and a helmet or full-face mask.<ref name="Doolette and Mitchell 2018" />

Several schedules have been published for in-water recompression treatment, but little data on their efficacy is available.<ref name="Doolette and Mitchell 2018" />

The decision of whether or not to attempt IWR is dependent on identifying the diver whose condition is serious enough to justify the risk, but whose clinical condition does not indicate that the risk is unacceptable. The risk may not be justified for mild DCI, if spontaneous recovery is probable whether the diver is recompressed or not, and surface oxygen is indicated for these cases. However, in these cases the risk of the recompression is also low, and early abandonment is also unlikely to cause further harm.<ref name="Doolette and Mitchell 2018" />

==== Contraindications ====
Some signs of decompression illness which suggest a risk of permanent injury are nevertheless considered contraindications for IWR.  Hearing loss and vertigo displayed in isolation with no other symptoms of DCI can have been caused by inner ear barotrauma rather than DCI, and inner ear barotrauma is generally considered a contraindication for recompression. Even when caused by DCI, vertigo can make in-water treatment hazardous if accompanied by nausea and vomiting. A diver with a deteriorating level of consciousness or with a persisting reduced level of consciousness should also not be recompressed in-water nor should a diver who does not want to go back down, or with a  history of oxygen toxicity in the preceding dives, or any physical injury or incapacitation which may make the procedure unsafe.<ref name="Doolette and Mitchell 2018" />