Editing Decompression sickness (section)

== Treatment ==
{{Further|Hyperbaric medicine}}
[[File:Nasa decompression chamber.jpg|thumb|alt=A large horizontal cylinder with a bank of instruments and monitors|The recompression chamber at the [[Neutral Buoyancy Lab]].]]
[[File:ХБОТ у једномесној барокомори.jpg|thumb|Hyperbaric oxygen treatment in a monoplace chamber|alt=View of the side of a small cylindrical structure with several curved windows and an instrument panel, with a person visible inside]]

Recompression on air was shown to be an effective treatment for minor DCS symptoms by Keays in 1909.{{r|Keays1909}} Evidence of the effectiveness of recompression therapy utilizing oxygen was first shown by Yarbrough and [[Albert R. Behnke|Behnke]],{{r|Yarbrough1939}} and has since become the standard of care for treatment of DCS.{{r|Berghage 1978}} Recompression is normally carried out in a [[recompression chamber]]. At a dive site, a riskier alternative is [[in-water recompression]].{{r|Edmonds1998 | Pyle1995 | Kay108}}<ref name="Doolette and Mitchell 2018" />

[[Oxygen first aid]] has been used as an emergency treatment for diving injuries for years.{{sfn|Moon & Gorman|p=616}} Particularly if given within the first four hours of surfacing, it increases the success of recompression therapy as well as decreasing the number of recompression treatments required.{{r|Longphre}} Most fully closed-circuit [[diving rebreather]]s can deliver sustained high concentrations of oxygen-rich [[breathing gas]] and could be used as a means of supplying oxygen if dedicated equipment is not available.{{r|Goble2003}}

It is beneficial to give fluids, as this helps reduce [[dehydration]]. It is no longer recommended to administer aspirin, unless advised to do so by medical personnel, as [[analgesics]] may mask symptoms. People should be made comfortable and placed in the supine position (horizontal), or the [[recovery position]] if vomiting occurs.{{r|ThalmannDAN}} In the past, both the [[Trendelenburg position]] and the left lateral [[decubitus position]] (Durant's maneuver) have been suggested as beneficial where air emboli are suspected,{{r|O'Dowd2000}} but are no longer recommended for extended periods, owing to concerns regarding [[cerebral edema]].{{sfn|Moon & Gorman|p=616}}{{r|Bove2009}}

===First aid===
All cases of decompression sickness should be treated initially with the highest available concentration of oxygen until [[hyperbaric oxygen therapy]] (100% oxygen delivered in a hyperbaric chamber) can be provided.{{sfn|Marx|p=1912}} Mild cases of the "bends" and some skin symptoms may disappear during descent from high altitude; however, it is recommended that these cases still be evaluated. Neurological symptoms, pulmonary symptoms, and mottled or marbled skin lesions should be treated with hyperbaric oxygen therapy if seen within 10 to 14 days of development.{{sfn|Marx|p=1813}} Early recompression has a history of better outcomes and less treatment being needed.<ref name="Doolette and Mitchell 2018" />

Normobaric oxygen administered at as close to 100% as practicable is known to be beneficial based on observed bubble reduction and symptom resolution. For this reason diver training in oxygen administration, and a system for administering a high percentage of inspired oxygen at quantities sufficient for plausible evacuation scenarios is desirable. Where oxygenation may be compromised the administration rate should be adjusted to ensure that the best practicable supplementation is maintained until supplies can be replenished.<ref name="Doolette and Mitchell 2018" />

A horizontal position is preferable during evacuation if possible, with the recovery position recommended for unconscious divers, as there is evidence that inert gas washout is improved in horizontal subjects, and that large arterial bubbles tend to distribute towards the head in upright positions. A head down position is thought to be harmful in DCS.<ref name="Doolette and Mitchell 2018" />

Oral hydration is recommended in fully conscious persons, and fluids should ideally be isotonic, without alcohol, carbonation or caffeine, as diving is known to cause dehydration, and rehydration is known to reduce post-dive venous gas emboli.<ref name="Doolette and Mitchell 2018" />

Intravascular rehydration is recommended if suitably competent responders are present. Glucose free [[Tonicity#Isotonicity|isotonic]] [[crystalloid solution]]s are preferred. Case evidence shows that aggressive rehydration can be life-saving in severe cases.<ref name="Doolette and Mitchell 2018" />

If there are no contraindications, a [[non-steroidal anti-inflammatory drug]] along with hyperbatic oxygen is likely to improve rate of recovery. The most prominent NSAIDs are [[aspirin]], [[ibuprofen]], and [[naproxen]]; all available [[Over-the-counter drug|over the counter]] in most countries.<ref name="The Physician and Sportsmedicine 20103" /> [[Paracetamol]] (acetaminophen) is generally not considered an NSAID because it has only minor anti-inflammatory activity.<ref name="Hinz_20083" />[[Corticosteroid]]s, [[pentoxyphylline]], [[aspirin]], [[lidocaine]] and [[nicergoline]] have been used in early management of DCS, but there is insufficient evidence on their effectiveness.<ref name="Doolette and Mitchell 2018" />

Divers should be kept comfortably warm, as warm subjects are known to eliminate gas more quickly, but overheating aggravates neurological injury.<ref name="Doolette and Mitchell 2018" />

===Delay of recompression===
Observational evidence shows that outcomes after recompression are likely to be better after immediate recompression, which is only possible when on-site recompression is possible, although the 2004 workshop on decompression came to the conclusion that for cases with mild symptoms, a delay before recompression is unlikely to cause any worsening of long-term outcomes.<ref name="Doolette and Mitchell 2018" />

In more serious cases recompression should be done as soon as safely possible. There is some evidence that delays longer than six hours result in slower or less complete recovery, and the number of treatments required may be increased.<ref name="Doolette and Mitchell 2018" />

===Transport of a symptomatic diver===
Exposing a case of decompression sickness to reduced ambient pressure will cause the bubbles to expand if not constrained by a rigid local tissue environment. This can aggravate the symptoms, and should be avoided if reasonably practicable. If a diver with DCS is transported by air, cabin pressure should be kept as close to sea level atmospheric pressure as possible, preferably not more than 150 m, either by cabin pressurisation or by remaining at low altitude throughout the flight. The risk of deterioration at higher altitudes must be considered against the risk of deterioration if not transported. Some divers with symptoms or signs of mild decompression sickness may be evacuated by pressurised commercial airliner for further treatment after a surface interval of at least 24 hours. The 2004 workshop considered it unlikely for this to cause a worse outcome. Most experience has been for short flights of less than two hours. There is little known about the effects of longer flights. Where possible, pre-flight and in-flight oxygen breathing at the highest available percentage is considered best practice. Similar precautions apply to surface transport through higher altitudes.<ref name="Doolette and Mitchell 2018" />

===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" />

===Definitive treatment===
{{Further|Hyperbaric treatment schedules}}

The duration of recompression treatment depends on the severity of symptoms, the dive history, the type of recompression therapy used and the patient's response to the treatment. One of the more frequently used [[Hyperbaric treatment schedules|treatment schedules]] is the [[Hyperbaric treatment schedules#US Navy Recompression Treatment Table 6|US Navy Table 6]], which provides hyperbaric oxygen therapy with a maximum pressure equivalent to {{convert|60|ft|m}} of seawater (2.8 bar P<sub>O<sub>2</sub></sub>) for a total time under pressure of 288 minutes, of which 240 minutes are on oxygen and the balance are air breaks to minimise the possibility of [[oxygen toxicity]].{{r|USNDM Table 6}}

A multiplace chamber is the preferred facility for treatment of decompression sickness as it allows direct physical access to the patient by medical personnel, but monoplace chambers are more widely available and should be used for treatment if a multiplace chamber is not available or transportation would cause significant delay in treatment, as the interval between onset of symptoms and recompression is important to the quality of recovery.{{r|Kindwall 1988}} It may be necessary to modify the optimum treatment schedule to allow use of a monoplace chamber, but this is usually better than delaying treatment. A US Navy treatment table 5 can be safely performed without air breaks if a built-in breathing system is not available.{{r|Kindwall 1988}} In most cases the patient can be adequately treated in a monoplace chamber at the receiving hospital.{{r|Kindwall 1988}}

===Altitude decompression sickness===
{{further|Decompression (altitude)}}

Treatment and management may vary depending on the grade or form of decompression sickness and the treating facility or organization. First aid at altitude is oxygen at the highest practicable concentration and earliest and largest practicable reduction in cabin altitude.

Ground-level 100% oxygen therapy is suggested for 2 hours following type-1 decompression sickness that occurs at altitude, if it resolves upon descent. In more severe cases, hyperbaric oxygen therapy following standard recompression protocols is indicated. Decompression sickness in aviation most commonly follows flights in non-pressurized aircraft, flights with cabin pressure fluctuations, or in individuals who fly after diving. Cases have also been reported after the use of altitude chambers. These are relatively rare clinical events.<ref name="Statpearls" />