Barotrauma refers to is physical damage to body tissues caused by a difference in pressure between a gas space inside, or in contact with, the body, and the surrounding gas or fluid.

The initial damage on barotrauma is usually due to over-stretching the tissues in tension or shear, either directly by expansion of the gas in the closed space or by pressure difference hydrostatically transmitted through the tissue. 

Tissue rupture can introduce gas into the local tissue or circulation through the initial trauma site, which can cause blockage of circulation at distant sites or interfere with normal function of an organ.

Mild barotrauma to a diver can cause mask squeeze, with surrounding skin showing petechial and subconjunctival hemmorhages.

Barotrauma generally manifests as sinus or middle ear effects, decompression sickness (DCS), lung overpressure injuries and injuries resulting from external squeezes.

Barotrauma typically occurs when there is a significant change in ambient pressure, such as when a scuba diver, a free-diver or an airplane passenger ascends or descends or during uncontrolled decompression of a pressure vessel such as a diving chamber or pressurised aircraft, but can also be caused by a shock wave. 

Ventilator-induced lung injury is caused by over-expansion of the lungs by mechanical ventilation used and is associated with relatively large tidal volumes and relatively high peak pressures. 

Arterial gas embolism refers to gas in the arterial system that can be carried to the blood vessels of the brain and other vital organs. 

It typically causes transient embolism similar to thromboembolism.

Middle ear barotitis.

Paranasal aerosinusitis


Where damage occurs to the endothelium inflammation develops and symptoms resembling stroke may follow. 

The bubbles of various sizes affect several areas, result in an unpredictable variety of neurological deficits. 

Venous gas can be admitted to the arterial circulation by passing through pulmonary or intracardial shunts, bypassing the pulmonary filter. 

Gas emboli are normally transient, and cause damage due to inflammation following endothelial injury and secondary injury from inflammatory mediator upregulation. 

Hyperbaric oxygen causes hyperoxic arterial vasoconstriction of the supply to capillary beds, and regulates the inflammatory response and resolution of edema:High concentration normobaric oxygen is not considered definitive treatment even when the symptoms appear to resolve, as relapses are common after discontinuing oxygen without recompression.

Diving causes pressure differences which cause the barotrauma changes trilateral to  hydrostatic pressure.

Divers experience surrounding pressure due to the atmospheric pressure and the water pressure.

A descent of 10 metres (33 feet) in water increases the ambient pressure by an amount approximately equal to the pressure of the atmosphere at sea level:

doubling of the pressure on the diver. 

Such a pressure change reduces the volume of a gas-filled space by half: Boyle’s law.

Barotraumas of descent prevents 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.

Barotraumas of ascent are also caused when the free change of volume of the gas in a closed space in contact with the diver is prevented: the pressure difference causes a resultant tension in the surrounding tissues which exceeds their tensile strength. 

Besides tissue rupture, the overpressure may cause gases into the tissues and through the circulatory system.

This pulmonary barotrauma of ascent is also known as pulmonary over-inflation syndrome (POIS), lung over-pressure injury (LOP) and burst lung.

Consequent injuries may include arterial gas embolism, pneumothorax, mediastinal, interstitial and subcutaneous emphysemas.

Breathing gas at depth from underwater breathing apparatus results in the lungs containing gas at a higher pressure than atmospheric pressure. 

A diver can dive to 10 metres (33 feet) and safely ascend without exhaling, because the gas in the lungs had been inhaled at atmospheric pressure, whereas a diver who inhales at 10 metres and ascends without exhaling has lungs containing twice the amount of gas at atmospheric pressure and is very likely to suffer life-threatening lung damage.

Explosive decompression of a hyperbaric environment can produce severe barotrauma, followed by severe decompression bubble formation and other related injury. The Byford Dolphin incident is an example.

An explosive blast and explosive decompression create a pressure wave that can induce barotrauma. 

As a result of a blast the difference in pressure between internal organs and the outer surface of the body causes injuries to internal organs that contain gas, such as the lungs, gastrointestinal tract, and ear.

Similarly, lung injuries can also occur during rapid decompression, with a risk of injury that is lower than with explosive decompression.

Mechanical ventilation can lead to barotrauma of the lungs by the 

absolute pressures used in order to ventilate non-compliant lungs, or the 

shearing forces, particularly associated with rapid changes in gas velocity.

With alveolar rupture pneumothorax, pulmonary interstitial emphysema and pneumomediastinum can occur.

Barotrauma from mechanical ventilation is most commonly associated with acute respiratory distress syndrome. 

The barotrauma 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.

There is no generally accepted safe pressure at which there is no risk.

The barotrauma complication of mechanical ventilation risk is increased by aspiration of stomach contents and pre-existing lung diseases.

When lung tissues are damaged by alveolar over-distension, the injury may be termed volutrauma.

Patients undergoing hyperbaric oxygen therapy must equalize their ears to avoid barotrauma.


In terms of barotrauma the diagnostic workup for the affected individual would include the following:

Creatine kinase (CPK) level, that indicate tissue damage associated with decompression sickness.

Complete blood count (CBC)

Arterial blood gas (ABG) determination


Chest radiography for pneumothorax.

Computed tomography (CT) scans and magnetic resonance imaging (MRI) may be indicated when there is severe headache or severe back pain after diving.

CT is the most sensitive method to evaluate for pneumothorax, and is used where barotrauma-related pneumothorax is suspected and chest radiograph findings are negative.

Echocardiography detects the number and size of gas bubbles in the right side of the heart.

Barotrauma can affect the external, middle, or inner ear. 

Middle ear barotrauma (MEBT) is the most common being experienced by between 10% and 30% of divers.

Middle ear barotrauma is due to insufficient equilibration of the middle ear. 

External ear barotrauma may occur on ascent if high pressure air is trapped in the external auditory canal:  tight fitting diving equipment or ear wax. 

Inner ear barotrauma is much less common than middle ear barotrauma.

Mechanical trauma to the inner ear can lead to varying degrees of conductive and sensorineural hearing loss as well as vertigo., and auditory hypersensitivity.

The sinuses are susceptible to barotrauma if their openings become obstructed and may be associated with pain as well as epistaxis.

Mask squeeze refers to a diver’s mask not being equalized during descent.

The relative negative pressure can produce petechial hemorrhages in the area covered by the mask along with subconjunctival hemorrhages.

Pulmonary barotrauma

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

The compressed gas in the lungs expands as the ambient pressure decreases causing the lungs to over-expand and rupture unless the diver allows the gas to escape by maintaining an open airway, as in normal breathing. 

Breath-hold divers as they bring a lungful of air with them from the surface, re-expanding safely to near its original volume on ascent.

If a breath of ambient pressure gas is taken at depth, it may  expand on ascent to more than the lung volume. 

Pulmonary barotrauma may also be caused by explosive decompression of a pressurized aircraft.

Ears and sinuses with barotrauma:

There is a risk of stretched or burst eardrums, usually crushed inwards during descent but sometimes stretched outwards on ascent. 

There is a risk of pneumothorax, arterial gas embolism, and mediastinal and subcutaneous emphysema during ascent in diving.

To equalize the lungs, all that is necessary is not to hold the breath during ascent. 

These risks do not occur when breath-hold diving from the surface, unless the diver breathes from an ambient pressure gas source underwater; breath-hold divers do suffer squeezed lungs on descent, crushing in the chest cavity, but, while uncomfortable, this rarely causes lung injury and returns to normal at the surface. 

Patients  with lung disease prevent rapid flow of excess air through the passages, which can lead to lung barotrauma even if the breath is not held during rapid depressurisation. 

Patients  with lung disease should not dive as the risk is unacceptably high. 

Diving mask squeeze that enclosed the eyes and nose risks rupture of the capillaries of the eyes and facial skin because of the negative pressure difference between the gas space and blood pressure, or orbital emphysema from higher pressures.

Diving mask squeeze can be avoided by breathing air into the mask through the nose. 

Goggles covering only the eyes are not suitable for deep diving:cannot be equalized.

Dry suit squeeze refers to the skin getting pinched and bruised by folds of the dry suit when squeezed on descent. 

Dry suits can be equalized against squeeze via a manually operated valve fed from a low pressure gas supply: Air is manually injected during the descent to avoid squeeze and is manually or automatically vented on the ascent to maintain buoyancy control.

Helmet squeeze occurs if the gas supply hose is severed above the diver and the non-return valve at the helmet gas inlet fails or is not fitted. 

This form of barotrauma is avoidable by controlled descent rate, which is standard practice for commercial divers.

Asthma, Marfan syndrome, and COPD pose a very high risk of pneumothorax, and  may be considered absolute contraindications, while in others the severity may be taken into consideration. 

Asthmatics with a mild and well controlled condition may be permitted to dive under restricted circumstances.

Ventilator induced lung injury (VILI) is affected by the interaction of barotrauma forces and the pre-existing state of the lung tissues, and dynamic changes in alveolar structure may be involved. 

Factors such as plateau pressure and positive end-expiratory pressure (PEEP) alone do not adequately predict injury, and cyclic deformation of lung tissue may play a large part in the cause of ventilator induced lung injury , and contributory factors probably include tidal volume, positive end-expiratory pressure and respiratory rate. 

Treatment of diving barotrauma depends on the symptoms. 

Over-pressure lung  injury may require a chest drain to remove air from the pleura or mediastinum. 

Hyperbaric oxygen therapy is the definitive treatment for arterial gas embolism.     

Barotraumas that do not involve gas in the tissues are generally treated according to severity and symptoms for similar trauma from other causes.

Pre-hospital care for lung barotrauma includes basic life support of maintaining adequate oxygenation and perfusion, venous access with isotonic fluid infusion is recommended to maintain blood pressure and pulse.

High-flow oxygen up to 100% is considered appropriate for diving accidents. and pulse.

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 hemothorax.

Intravenous hydration may be required to maintain adequate blood pressure.

Therapeutic recompression is indicated for severe arterial getting as embolism.

Air transport should be below 1,000 feet, if possible, or in a pressurized aircraft which should be pressurized to as low an altitude as reasonably possible.

Sinus squeeze and middle ear squeeze are treated with decongestants to reduce the pressure differential.

Suit, helmet and mask squeeze are treated as traumatic injuries.

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

Following barotrauma of the ears or lungs from diving, recovery can take weeks to months.

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