Treatment of diving disorders depends on the specific disorder or combination of disorders, but two treatments are commonly associated with first aid and definitive treatment where diving is involved. These are first aid oxygen administration at high concentration, which is seldom contraindicated, and generally recommended as a default option in diving accidents where there is any significant probability of hypoxia, and hyperbaric oxygen therapy (HBO), which is the definitive treatment for most incidences of decompression illness. Hyperbaric treatment on other breathing gases is also used for treatment of decompression sickness if HBO is inadequate.

The administration of oxygen as a medical intervention is common in diving medicine, both for first aid and for longer term treatment.

First aid is common for both DCS and AGE:

- Monitor the patient for responsiveness, airway, breathing and circulation, resuscitate if necessary.

- Treat for shock.

- Lay the patient on their back, or for drowsy, unconscious, or nauseated victims, on their side.

- Administer 100% oxygen as soon as possible.

- Seek immediate medical assistance, locate a hospital with hyperbaric facilities and plan for possible transport.

- Allow the patient to drink water or isotonic fluids only if responsive, stable, and not suffering from nausea or stomach pain. Administration of intravenous saline solution is preferable.

- Record details of recent dives and responses to first aid treatment and provide to the treating medical specialist. The diving details should include depth and time profiles, breathing gases used and surface intervals.

All cases of decompression sickness should be treated initially with 100% oxygen until hyperbaric oxygen therapy (100% oxygen delivered in a high-pressure chamber) can be provided. 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.

Recompression on air was shown to be an effective treatment for minor DCS symptoms by Keays in 1909. Evidence of the effectiveness of recompression therapy utilizing oxygen was first shown by Yarbrough and Behnke, and has since become the standard of care for treatment of DCS. Recompression is normally carried out in a recompression chamber. At a dive site, a riskier alternative is in-water recompression.

Oxygen first aid has been used as an emergency treatment for diving injuries for years. 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. Most fully closed-circuit rebreathers 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.

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. 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, but are no longer recommended for extended periods, owing to concerns regarding cerebral edema.

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 treatment schedules is the US Navy Table 6, which provides hyperbaric oxygen therapy with a maximum pressure equivalent to of seawater 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.

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. 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. In most cases the patient can be adequately treated in a monoplace chamber at the receiving hospital.

Treatment for the "Decompression Sickness" and the "Arterial Gas Embolism" components of DCI may differ significantly. Refer to the separate treatments under those articles.

Immediate treatment with 100% oxygen, followed by recompression in a hyperbaric chamber, will in most cases result in no long-term effects. However, permanent long-term injury from DCS is possible. Three-month follow-ups on diving accidents reported to DAN in 1987 showed 14.3% of the 268 divers surveyed had ongoing symptoms of Type II DCS, and 7% from Type I DCS. Long-term follow-ups showed similar results, with 16% having permanent neurological sequelae.

The most straightforward way to avoid nitrogen narcosis is for a diver to limit the depth of dives. Since narcosis becomes more severe as depth increases, a diver keeping to shallower depths can avoid serious narcosis. Most recreational dive schools will only certify basic divers to depths of , and at these depths narcosis does not present a significant risk. Further training is normally required for certification up to on air, and this training should include a discussion of narcosis, its effects, and cure. Some diver training agencies offer specialized training to prepare recreational divers to go to depths of , often consisting of further theory and some practice in deep dives under close supervision. Scuba organizations that train for diving beyond recreational depths, may forbid diving with gases that cause too much narcosis at depth in the average diver, and strongly encourage the use of other breathing gas mixes containing helium in place of some or all of the nitrogen in air – such as trimix and heliox – because helium has no narcotic effect. The use of these gases forms part of technical diving and requires further training and certification.

While the individual diver cannot predict exactly at what depth the onset of narcosis will occur on a given day, the first symptoms of narcosis for any given diver are often more predictable and personal. For example, one diver may have trouble with eye focus (close accommodation for middle-aged divers), another may experience feelings of euphoria, and another feelings of claustrophobia. Some divers report that they have hearing changes, and that the sound their exhaled bubbles make becomes different. Specialist training may help divers to identify these personal onset signs, which may then be used as a signal to ascend to avoid the narcosis, although severe narcosis may interfere with the judgement necessary to take preventive action.

Deep dives should be made only after a gradual training to test the individual diver's sensitivity to increasing depths, with careful supervision and logging of reactions. Diving organizations such as Global Underwater Explorers (GUE) emphasize that such sessions are for the purpose of gaining experience in recognizing the onset symptoms of narcosis for an individual , which are somewhat more repeatable than for the average group of divers. Scientific evidence does not show that a diver can train to overcome any measure of narcosis at a given depth or become tolerant of it.

Equivalent narcotic depth (END) is a commonly used way of expressing the narcotic effect of different breathing gases. The National Oceanic and Atmospheric Administration (NOAA) Diving Manual now states that oxygen and nitrogen should be considered equally narcotic. Standard tables, based on relative lipid solubilities, list conversion factors for narcotic effect of other gases. For example, hydrogen at a given pressure has a narcotic effect equivalent to nitrogen at 0.55 times that pressure, so in principle it should be usable at more than twice the depth. Argon, however, has 2.33 times the narcotic effect of nitrogen, and is a poor choice as a breathing gas for diving (it is used as a drysuit inflation gas, owing to its low thermal conductivity). Some gases have other dangerous effects when breathed at pressure; for example, high-pressure oxygen can lead to oxygen toxicity. Although helium is the least intoxicating of the breathing gases, at greater depths it can cause high pressure nervous syndrome, a still mysterious but apparently unrelated phenomenon. Inert gas narcosis is only one factor influencing the choice of gas mixture; the risks of decompression sickness and oxygen toxicity, cost, and other factors are also important.

Because of similar and additive effects, divers should avoid sedating medications and drugs, such as marijuana and alcohol before any dive. A hangover, combined with the reduced physical capacity that goes with it, makes nitrogen narcosis more likely. Experts recommend total abstinence from alcohol for at least 12 hours before diving, and longer for other drugs. Abstinence time needed for marijuana is unknown, but owing to the much longer half-life of the active agent of this drug in the body, it is likely to be longer than for alcohol.

The primary medications for lung barotrauma are oxygen, oxygen-helium or nitrox, isotonic fluids, anti-inflammatory medications, decongestants, and analgesics.

Pulmonary barotrauma:

- Endotracheal intubation may be required if the airway is unstable or hypoxia persists when breathing 100% oxygen.

- Needle decompression or tube thoracostomy may be necessary to drain a pneumothorax or haemothorax

- Foley catheterization may be necessary for spinal cord AGE if the person is unable to urinate.

- Intravenous hydration may be required to maintain adequate blood pressure.

- Therapeutic recompression is indicated for severe AGE. The diving medical practitioner will need to know the vital signs and relevant symptoms, along with the recent pressure exposure and breathing gas history of the patient. Air transport should be below if possible, or in a pressurized aircraft which should be pressurised to as low an altitude as reaonably possible.

Sinus squeeze and middle ear squeeze are generally treated with decongestants to reduce the pressure differential, with anti-inflammatory medications to treat the pain. For severe pain, narcotic analgesics may be appropriate.

Suit, helmet and mask squeeze are treated as trauma according to symptoms and severity.

Oxygen first aid treatment is useful for suspected gas embolism casualties or divers who have made fast ascents or missed decompression stops. Most fully closed-circuit rebreathers can deliver sustained high concentrations of oxygen-rich breathing gas and could be used as an alternative to pure open-circuit oxygen resuscitators. However pure oxygen from an oxygen cylinder through a Non-rebreather mask is the optimal way to deliver oxygen to a decompression illness patient.

Recompression is the most effective, though slow, treatment of gas embolism in divers. Normally this is carried out in a recompression chamber. As pressure increases, the solubility of a gas increases, which reduces bubble size by accelerating absorption of the gas into the surrounding blood and tissues. Additionally, the volumes of the gas bubbles decrease in inverse proportion to the ambient pressure as described by Boyle's law. In the hyperbaric chamber the patient may breathe 100% oxygen, at ambient pressures up to a depth equivalent of 18 msw. Under hyperbaric conditions, oxygen diffuses into the bubbles, displacing the nitrogen from the bubble and into solution in the blood. Oxygen bubbles are more easily tolerated. Diffusion of oxygen into the blood and tissues under hyperbaric conditions supports areas of the body which are deprived of blood flow when arteries are blocked by gas bubbles. This helps to reduce ischemic injury. The effects of hyperbaric oxygen also counteract the damage that can occur with reperfusion of previously ischemic areas; this damage is mediated by leukocytes (a type of white blood cell).

Prevention is a more successful strategy than treatment. By using the most conservative decompression schedule reasonably practicable, and by minimizing the number of major decompression exposures, the risk of DON may be reduced. Prompt treatment of any symptoms of decompression sickness (DCS) with recompression and hyperbaric oxygen also reduce the risk of subsequent DON.

Treatment is difficult, often requiring a joint replacement. Spontaneous improvement occasionally happens and some juxta-articular lesions do not progress to collapse. Other treatments include immobilization and osteotomy of the femur. Cancellous bone grafts are of little help.

Administration of oxygen at 15 litres per minute by face mask or bag valve mask is often sufficient, but tracheal intubation with mechanical ventilation may be necessary. Suctioning of pulmonary oedema fluid should be balanced against the need for oxygenation. The target of ventilation is to achieve 92% to 96% arterial saturation and adequate chest rise. Positive end-expiratory pressure will generally improve oxygenation. Drug administration via peripheral veins is preferred over endotracheal administration. Hypotension remaining after oxygenation may be treated by rapid crystalloid infusion. Cardiac arrest in drowning usually presents as asystole or pulseless electrical activity. Ventricular fibrillation is more likely to be associated with complications of pre-existing coronary artery disease, severe hypothermia, or the use of epinephrine or norepinephrine.

The checks for responsiveness and breathing are carried out with the person horizontally supine. If unconscious but breathing, the recovery position is appropriate. If not breathing, rescue ventilation is necessary. Drowning can produce a gasping pattern of apnea while the heart is still beating, and ventilation alone may be sufficient, as the heart may be basically healthy, but hypoxic. The airway-breathing-circulation (ABC) sequence should be followed, rather than starting with compressions as is typical in cardiac arrest, as the basic problem is lack of oxygen. Five initial breaths are recommended, as the initial ventilation may be difficult because of water in the airways which can interfere with effective alveolar inflation. Thereafter a sequence of two breaths and 30 chest compressions is recommended, repeated until vital signs are re-established, the rescuers are unable to continue, or advanced life support is available.

Attempts to actively expel water from the airway by abdominal thrusts, Heimlich maneuver or positioning head downwards should be avoided as there is no obstruction by solids, and they delay the start of ventilation and increase the risk of vomiting, with a significantly increased risk of death, as aspiration of stomach contents is a common complication of resuscitation efforts.

Treatment for hypothermia may also be necessary. Because of the diving reflex, people submerged in cold water and apparently drowned may revive after a relatively long period of immersion. Rescuers retrieving a child from water significantly below body temperature should attempt resuscitation even after protracted immersion.

Narcosis is potentially one of the most dangerous conditions to affect the scuba diver below about . Except for occasional amnesia of events at depth, the effects of narcosis are entirely removed on ascent and therefore pose no problem in themselves, even for repeated, chronic or acute exposure. Nevertheless, the severity of narcosis is unpredictable and it can be fatal while diving, as the result of illogical behavior in a dangerous environment.

Tests have shown that all divers are affected by nitrogen narcosis, though some experience lesser effects than others. Even though it is possible that some divers can manage better than others because of learning to cope with the subjective impairment, the underlying behavioral effects remain. These effects are particularly dangerous because a diver may feel they are not experiencing narcosis, yet still be affected by it.

It is likely that HPNS cannot be entirely prevented but there are effective methods to delay or change the development of the symptoms.

Utilizing slow rates of compression or adding stops to the compression have been found to prevent large initial decrements in performance.

Including other gases in the helium–oxygen mixture, such as nitrogen (creating trimix) or hydrogen (producing hydreliox) suppresses the neurological effects.

Alcohol, anesthetics and anticonvulsant drugs have had varying results in suppressing HPNS with animals. None are currently in use for humans.

High incidence of relapse after hyperbaric oxygen treatment due to delayed cerebral edema.

To counter the effects of high-altitude diseases, the body must return arterial p toward normal. Acclimatization, the means by which the body adapts to higher altitudes, only partially restores p to standard levels. Hyperventilation, the body’s most common response to high-altitude conditions, increases alveolar p by raising the depth and rate of breathing. However, while p does improve with hyperventilation, it does not return to normal. Studies of miners and astronomers working at 3000 meters and above show improved alveolar p with full acclimatization, yet the p level remains equal to or even below the threshold for continuous oxygen therapy for patients with chronic obstructive pulmonary disease (COPD). In addition, there are complications involved with acclimatization. Polycythemia, in which the body increases the number of red blood cells in circulation, thickens the blood, raising the danger that the heart can’t pump it.

In high-altitude conditions, only oxygen enrichment can counteract the effects of hypoxia. By increasing the concentration of oxygen in the air, the effects of lower barometric pressure are countered and the level of arterial p is restored toward normal capacity. A small amount of supplemental oxygen reduces the equivalent altitude in climate-controlled rooms. At 4000 m, raising the oxygen concentration level by 5 percent via an oxygen concentrator and an existing ventilation system provides an altitude equivalent of 3000 m, which is much more tolerable for the increasing number of low-landers who work in high altitude. In a study of astronomers working in Chile at 5050 m, oxygen concentrators increased the level of oxygen concentration by almost 30 percent (that is, from 21 percent to 27 percent). This resulted in increased worker productivity, less fatigue, and improved sleep.

Oxygen concentrators are uniquely suited for this purpose. They require little maintenance and electricity, provide a constant source of oxygen, and eliminate the expensive, and often dangerous, task of transporting oxygen cylinders to remote areas. Offices and housing already have climate-controlled rooms, in which temperature and humidity are kept at a constant level. Oxygen can be added to this system easily and relatively cheaply.

A prescription renewal for home oxygen following hospitalization requires an assessment of the patient for ongoing hypoxemia.

Dysbarism refers to medical conditions resulting from changes in ambient pressure. Various activities are associated with pressure changes. underwater diving is the most frequently cited example, but pressure changes also affect people who work in other pressurized environments (for example, caisson workers), and people who move between different altitudes.

Management has generally been reported to be conservative, though deaths have been reported.

- Removal from water

- Observation

- Diuretics and / or Oxygen when necessary

- Episodes are generally self-limiting in the absence of other medical problems

High pressure nervous syndrome is rarely of importance to recreational divers. Breathing any gas at great depths (hundreds of feet) can cause seizures. Interestingly it was discovered because divers were using gas mixtures without nitrogen to be able to go to great depths without experiencing nitrogen narcosis. It turns out that nitrogen prevents HPNS. The answer? Add very small amounts of nitrogen to gas mixes when diving at great depth, small enough to avoid nitrogen narcosis, but sufficient to prevent HPNS.

Subcutaneous emphysema is usually benign. Most of the time, SCE itself does not need treatment (though the conditions from which it results may); however, if the amount of air is large, it can interfere with breathing and be uncomfortable. It occasionally progresses to a state "Massive Subcutaneous Emphysema" which is quite uncomfortable and requires surgical drainage. When the amount of air pushed out of the airways or lung becomes massive, usually due to positive pressure ventilation, the eyelids swell so much that the patient cannot see. Also the pressure of the air may impede the blood flow to the areolae of the breast and skin of the scrotum or labia. This can lead to necrosis of the skin in these areas. The latter are urgent situations requiring rapid, adequate decompression. Severe cases can compress the trachea and do require treatment.

In severe cases of subcutaneous emphysema, catheters can be placed in the subcutaneous tissue to release the air. Small cuts, or "blow holes", may be made in the skin to release the gas. When subcutaneous emphysema occurs due to pneumothorax, a chest tube is frequently used to control the latter; this eliminates the source of the air entering the subcutaneous space. If the volume of subcutaneous air is increasing, it may be that the chest tube is not removing air rapidly enough, so it may be replaced with a larger one. Suction may also be applied to the tube to remove air faster. The progression of the condition can be monitored by marking the boundaries with a special pencil for marking on skin.

Since treatment usually involves dealing with the underlying condition, cases of spontaneous subcutaneous emphysema may require nothing more than bed rest, medication to control pain, and perhaps supplemental oxygen. Breathing oxygen may help the body to absorb the subcutaneous air more quickly.

In closed circuit SCUBA (rebreather) diving, exhaled carbon dioxide must be removed from the breathing system, usually by a scrubber containing a solid chemical compound with a high affinity for CO, such as soda lime. If not removed from the system, it may be re-inhaled, causing an increase in the inhaled concentration.

Small spontaneous pneumothoraces do not always require treatment, as they are unlikely to proceed to respiratory failure or tension pneumothorax, and generally resolve spontaneously. This approach is most appropriate if the estimated size of the pneumothorax is small (defined as <50% of the volume of the hemithorax), there is no breathlessness, and there is no underlying lung disease. It may be appropriate to treat a larger PSP conservatively if the symptoms are limited. Admission to hospital is often not required, as long as clear instructions are given to return to hospital if there are worsening symptoms. Further investigations may be performed as an outpatient, at which time X-rays are repeated to confirm improvement, and advice given with regard to preventing recurrence (see below). Estimated rates of resorption are between 1.25% and 2.2% the volume of the cavity per day. This would mean that even a complete pneumothorax would spontaneously resolve over a period of about 6 weeks. There is, however, no high quality evidence comparing conservative to non conservative management.

Secondary pneumothoraces are only treated conservatively if the size is very small (1 cm or less air rim) and there are limited symptoms. Admission to the hospital is usually recommended. Oxygen given at a high flow rate may accelerate resorption as much as fourfold.

If pneumothorax occurs in a smoker, this is considered an opportunity to emphasize the markedly increased risk of recurrence in those who continue to smoke, and the many benefits of smoking cessation. It may be advisable for someone to remain off work for up to a week after a spontaneous pneumothorax. If the person normally performs heavy manual labor, several weeks may be required. Those who have undergone pleurodesis may need two to three weeks off work to recover.

Air travel is discouraged for up to seven days after complete resolution of a pneumothorax if recurrence does not occur. Underwater diving is considered unsafe after an episode of pneumothorax unless a preventative procedure has been performed. Professional guidelines suggest that pleurectomy be performed on both lungs and that lung function tests and CT scan normalize before diving is resumed. Aircraft pilots may also require assessment for surgery.