[1][21] Barotraumas of descent, also known as compression barotrauma, and squeezes, are caused by preventing the free change of volume of the gas in a closed space in contact with the diver, resulting in a pressure difference between the tissues and the gas space, and the unbalanced force due to this pressure difference causes deformation of the tissues resulting in cell rupture.

Collapse of a pressure resistant structure such as a submarine, submersible, or atmospheric diving suit can cause rapid compression barotrauma.

It used to be the most common complication of mechanical ventilation but can usually be avoided by limiting tidal volume and plateau pressure to less than 30 to 50 cm water column (30 to 50 mb).

[28] When lung tissues are damaged by alveolar over-distension, the injury may be termed volutrauma, but volume and transpulmonary pressure are closely related.

[30] A free-diver can dive and safely ascend without exhaling, because the gas in the lungs had been inhaled at atmospheric pressure, is compressed during the descent, and expands back to the original volume during ascent.

The bubbles are generally distributed and of various sizes, and usually affect several areas, resulting in an unpredictable variety of neurological deficits.

Unconsciousness or other major changes to the state of consciousness within about 10 minutes of surfacing are generally assumed to be gas embolism until proven otherwise.

[33] In a minority of cases, a one-way valve is formed by an area of damaged tissue, and the amount of air in the space between chest wall and lungs increases; this is called a tension pneumothorax.

Divers breathing compressed air (such as when scuba diving) may develop a pneumothorax as a result of barotrauma from ascending just 1 metre (3 ft) while breath-holding with their lungs fully inflated.

[38] Other conditions that can result in similar symptoms include a hemothorax (buildup of blood in the pleural space), pulmonary embolism, and heart attack.

Diagnosis of barotrauma generally involves a history of exposure to a source of pressure which could cause the injury suggested by the symptoms.

Diagnosis of middle and external ear barotrauma is relatively simple, as the damage is usually visible if severe enough to require intervention.

Barotrauma can occur in the external auditory canal if it is blocked by cerumen, exostoses, a tight-fitting diving suit hood or earplugs, which create an airtight, air-filled space between the eardrum and the blockage.

On descent, a pressure differential develops between the ambient water and the interior of this space, and this can cause swelling and haemorrhagic blistering of the canal.

In the other, the tube remains closed and increased cerebrospinal fluid pressure is transmitted through the cochlea and causes outward rupture of the round window.

[46] Divers who develop cochlear and/or vestibular symptoms during descent to any depth, or during shallow diving in which decompression sickness is unlikely, should be treated with bed rest with head elevation, and should avoid any activity which could cause raised cerebrospinal fluid and intralabyrinthine pressure.

[clarification needed] If there is no improvement in symptoms after 48 hours, exploratory tympanotomy may be considered to investigate possible repair of a labyrinthine window fistula.

[47] Limited case data suggest that recompression does not usually cause harm if the differential diagnosis between IEBt vs IEDCS is doubtful.

Lung over-pressure injury in ambient pressure divers using underwater breathing apparatus is usually caused by breath-holding on ascent.

Pulmonary barotrauma may also be caused by explosive decompression of a pressurised aircraft,[50] as occurred on 1 February 2003 to the crew in the Space Shuttle Columbia disaster.

Barotrauma may be caused when diving, either from being crushed, or squeezed, on descent or by stretching and bursting on ascent; both can be avoided by equalising the pressures.

A positive unbalanced pressure expands internal spaces rupturing tissue and can be equalised by letting air out, for example by exhaling.

There are a variety of techniques depending on the affected area and whether the pressure inequality is a squeeze or an expansion: Professional divers are screened for risk factors during initial and periodical medical examination for fitness to dive.

The damage is affected by the interaction of these forces and the pre-existing state of the lung tissues, and dynamic changes in alveolar structure may be involved.

Cyclic deformation of lung tissue may play a large part in the cause of VILI, and contributory factors probably include tidal volume, positive end-expiratory pressure and respiratory rate.

Diving injuries tend to correlate with trait anxiety and a tendency to panic, lack of experience, advancing age and reduction in fitness, alcohol usage, obesity, asthma, chronic sinusitis and otitis.

[69] Whales and dolphins develop severely disabling barotrauma when exposed to excessive pressure changes induced by navy sonar, oil industry airguns, explosives, undersea earthquakes and volcanic eruptions.

[citation needed] Injury and mortality of fish, marine mammals, including sea otters, seals, dolphins and whales, and birds by underwater explosions has been recorded in several studies.

The swim bladder is an organ of buoyancy control which is filled with gas extracted from solution in the blood, and which is normally removed by the reverse process.

Barotrauma can be directly fatal or disable the fish rendering it vulnerable to predation, but rockfish are able to recover if they are returned to depths similar to those they were pulled up from, shortly after surfacing.