Barotrauma 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 is usually due to over-stretching the tissues in tension or shear, either directly by expansion of the gas in...
Barotrauma 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 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 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 normal function of an organ by its presence. Barotrauma generally manifests as sinus or middle ear effects, decompression sickness , lung overpressure injuries and injuries resulting from external squeezes. 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 pressurised aircraft, but can also be caused by a shock wave. Ventilator-induced lung injury 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. Bats can be killed by lung barotrauma when flying in low-pressure regions close to operating wind-turbine blades. Examples of organs or tissues easily damaged by barotrauma are: Gas in the arterial system can be carried to the blood vessels of the brain and other vital organs. Unconsciousness or other major changes to the state of consciousness within about 10 minutes of surfacing or completion of a procedure are generally assumed to be gas embolism until proven otherwise. The belief that the gas bubbles themselves formed static emboli which remain in place until recompression has been superseded by the knowledge that the gas emboli are normally transient, and the damage is due to inflammation following endothelial damage and secondary injury from inflammatory mediator upregulation. Hyperbaric oxygen can cause downregulation of the inflammatory response and resolution of oedema by causing hyperoxic arterial vasoconstriction of the supply to capillary beds. Relapses are common after discontinuing oxygen without recompression. 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 in water increases the ambient pressure by an amount approximately equal to the pressure of the atmosphere at sea level.