barotrauma barotrauma barotrauma is physical damage to body tissues caused by a difference in pressure between a gas space inside, or contact with, the body and the surrounding gas or liquid. the initial damage is usually due to over-stretching the tissues in tension or shear, either directly by an expansion of the gas in the closed space or by pressure difference hydrostatically transmitted through the tissue. tissue rupture may be complicated by the introduction of gas into the local tissue or circulation through the initial trauma site, which can cause blockage of circulation at distant sites or interfere with the normal function of an organ by its presence. barotraumaother namessqueeze, decompression illness, lung overpressure injury, volutraumamild barotrauma to a diver caused by mask squeeze. eye and surrounding skin showing petechial and subconjunctival haemmorhages.symptomsdependent on locationcomplicationsarterial gas embolism, pneumothorax, mediastinal emphysemacausespressure difference between the environment and a gas-filled space in or in contact with the affected tissues barotrauma generally manifests as sinus or middle ear effects, lung overpressure injuries and injuries resulting from external squeezes. decompression sickness is indirectly caused by ambient pressure reduction, and tissue damage is caused directly and indirectly by gas bubbles. however, these bubbles form out of supersaturated solution from dissolved gases, and are not generally considered barotrauma. decompression illness is a term that includes decompression sickness and arterial gas embolism caused by lung overexpansion barotrauma. it is also classified under the broader term of dysbarism, which covers all medical conditions resulting from changes in ambient pressure. barotrauma typically occurs when the organism is exposed to 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 pressurized aircraft, but can also be caused by a shock wave. ventilator-induced lung injury (vili) is a condition caused by over-expansion of the lungs by mechanical ventilation used when the body is unable to breathe for itself and is associated with relatively large tidal volumes and relatively high peak pressures. barotrauma due to overexpansion of an internal gas-filled space may also be termed volutrauma. bats can be killed by lung barotrauma when flying in low-pressure regions close to operating wind-turbine blades, and fish with sealed swim bladders experience barotrauma when pulled up from the depths. the diagnosis and contribution of barotrauma to bat deaths near wind turbine blades have been called into question by other research. presentation examples of organs or tissues easily damaged by barotrauma are: middle ear and inner ear (barotitis or aerotitis) paranasal sinuses (causing aerosinusitis) lungs eyes (the under-pressure air space is inside the diving mask) skin (when wearing a diving suit which creates an air space) brain and cranium (temporal lobe injury secondary to temporal bone rupture) teeth (causing barodontalgia, i.e., barometric pressure related dental pain, or dental fractures) genital squeeze and associated urinary complications of p-valve use. causes any cause of sufficiently large and rapid environmental pressure change can potentially cause barotrauma. several commonly recognised examples are listed below. pressure differences while diving when diving, the pressure differences which cause the barotrauma are changes in hydrostatic pressure: there are two components to the surrounding pressure acting on the diver: 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. so, a descent from the surface to 10 metres (33 feet) underwater results in a doubling of the pressure on the diver. this pressure change will reduce the volume of a flexible gas-filled space by half. boyle's law describes the relationship between the volume of the gas space and the pressure in the gas. barotraumas of descent 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. 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. in this case the pressure difference causes a resultant tension in the surrounding tissues which exceeds their tensile strength. use of a hyperbaric chamber patients undergoing hyperbaric oxygen therapy must equalize their ears to avoid barotrauma. high risk of otic barotrauma is associated with unconscious patients. rapid decompression of a pressurised artificial environment 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. rapid uncontrolled decompression from caissons, airlocks, pressurised aircraft, spacecraft, and pressure suits can have similar effects of decompression barotrauma. rapid pressurisation of an artificial environment collapse of a pressure resistant structure such as a submarine, submersible, or atmospheric diving suit can cause rapid compression barotrauma. rapid change of altitude a rapid change of altitude can cause barotrauma when internal air spaces cannot be equalised. self inflicted barotrauma excessively strenuous efforts to equalise the ears using the valsalva manoeuvre can overpressurise the middle ear, and can cause middle ear and/or inner ear barotrauma. blast-induced barotrauma an explosive blast and explosive decompression create a pressure wave that can induce barotrauma. 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. lung injuries can also occur during rapid decompression, although the risk of injury is lower than with explosive decompression. ventilator-induced barotrauma