Editing In-water recompression (section)

== Factors influencing a decision to use IWR ==
Recompression and hyperbaric oxygen administered in a recompression chamber are 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 with oxygen is an option where a group of divers, including the symptomatic diver, already have the necessary equipment and relevant training and knowledge that provides a sufficient understanding of the associated risks to allow the involved parties to collectively accept responsibility for a decision to proceed with IWR.<ref name="Mitchell et al 2018" />

The decision of whether or not to attempt IWR depends 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" /> There are no firm guidelines regarding expected delay to access of a decompression chamber, but divers generally consider a predicted delay of more than 8 hours from symptom onset to be reason to consider in-water recompression.<ref name="Walker and Murphy-Lavoie" />

=== Environmental conditions===
Water conditions, such as low temperature and rough sea state are relative contraindications, and the team must take these factors into account. Divers undergoing IWR risk becoming cold or hypothermic. They may already have done long dives in cold water, but the use of dry suits is common for such conditions, and the use of active heating systems in dry suit undergarments may be available. IWR requires a stable platform that can remain in one place for three hours. These factors should be considered when deciding whether to undertake IWR. Deteriorating condition of the diver or environmental conditions may make it necessary to abort or shorten treatment, or terminate it before full resolution.<ref name="Doolette and Mitchell 2018" /> There is no known reason to assume that this would be inherently worse than not providing what treatment is possible at reasonable risk.

===Indications===
Indications are based on symptoms and signs of [[decompression illness]] where expected benefits are likely to outweigh risk. There is a tension between conditions serious enough to justify the risks and clinical states which indicate excessive risk. Risk may not be considered justified for cases where the symptoms suggest a spontaneous recovery is likely without recompression, although the actual risk in these cases is likely to be relatively low. As of 2018 there is no widely accepted method for objectively selecting divers suitable for in-water recompression, and although remote consultation with a diving medical practitioner is advised by the Doolette and Mitchell 2018 protocol, it is likely that remote advice will vary significantly depending on who is contacted and how willing they are to accept responsibility for giving advice on a procedure with which they may have little personal experience and for which there is no clear decision tree.<ref name="Doolette and Mitchell 2018" />

An attempt has been made to provide some structure to the decision process which can be useful to divers without medical training, by the technical diving certification organisation [[International Association of Nitrox and Technical Divers]] (IANTD), which in consultation with diving medical experts, produced a decision map for field use. The system relies entirely on gross observation, omitting a detailed neurological examination. It categorises symptoms into three "tiers", which correspond roughly with perceived severity of DCI, and appropriateness of IWR in suitable conditions.<ref name="Doolette and Mitchell 2018" />

Tier 1 symptoms would not be severe enough to justify IWR, but would be monitored and discussed with a remote consultant. These are generally non-specific symptoms which may or may not be of DCI, and are not an immediate or significant threat, such as headache, lethargy, or nausea.<ref name="Doolette and Mitchell 2018" />

Tier 2 symptoms are severe enough to suggest IWR if they present soon after surfacing, or are progressive, but not necessarily if there is a delay of some hours and the symptoms are not progressive. IWR would be justified for tier 2 when it may prevent the development of more severe symptoms. These symptoms are likely to be of DCI, but are not likely to result in permanent injury or death if not treated. They include musculoskeletal pain, excepting symmetrical ''girdle pains'', lymphatic obstruction with subcutaneous swelling, skin rashes and [[Paresthesia|paraesthesias]] such as tingling.<ref name="Doolette and Mitchell 2018" />

Tier 3: symptoms are severe enough to justify IWR if there are no contraindications and the logistical requirements are in place. These symptoms and signs are likely to be of DCI and indicate a risk of permanent injury or death. Some of them are also contraindications to IWR. They include changes in state of consciousness, or obvious confusion, difficulty with speech, visual changes,{{clarify|date=September 2022}} disturbances in balance, obvious sensory loss (numbness), obvious weakness or paralysis, bladder dysfunction, (usually inability to urinate), bowel dysfunction, loss of limb coordination, shortness of breath, and bilaterally symmetrical girdle pains.<ref name="Doolette and Mitchell 2018" />

=== Contraindications ===
Symptoms of mild DCS have been described as being one or more of musculoskeletal pain, rash, subjective sensory change in a non-dermatomal distribution, and constitutional symptoms such as fatigue. Divers with only these symptoms could be adequately managed with surface oxygen, observation, and consultation with a diving physician. Exposing divers with stable mild symptoms to the risks of IWR might not be justified. In severe cases the diver may be so compromised that they could not safely endure the procedure. It may be difficult or impossible to reliably codify the decision process.<ref name="Doolette and Mitchell 2018" />

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, altered level of consciousness, shock, respiratory distress, or any physical injury or incapacitation which may make the procedure unsafe.<ref name="Doolette and Mitchell 2018" /> Suspected or confirmed cases of [[arterial gas embolism]] (AGE) are generally not considered suitable for IWR due to the high probability of loss of consciousness.<ref name="Walker and Murphy-Lavoie" />