Pressure differences while diving When diving, the pressure differences which cause the<unk>  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 gas-filled space by half. Boyle's law describes the relationship between the volume of the gas space and the pressure in the gas.<unk> s 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.<unk> s 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. Besides tissue rupture, the overpressure may cause ingress of gases into the tissues and further afield through the circulatory system. This pulmonary<unk>  (PBt) 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, not usually all at the same time. Breathing gas at depth from underwater breathing apparatus results in the lungs containing gas at a higher pressure than atmospheric pressure. So a free-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<unk> , followed by severe decompression bubble formation and other related injury. The Byford Dolphin incident is an example. Blast-induced<unk>  An explosive blast and explosive decompression create a pressure wave that can induce<unk> . 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<unk>  Mechanical ventilation can lead to<unk>  of the lungs. This can be due to either: * absolute pressures used in order to ventilate non-compliant lungs. * shearing forces, particularly associated with rapid changes in gas velocity. The resultant alveolar rupture can lead to pneumothorax, pulmonary interstitial emphysema (PIE) and pneumomediastinum.<unk>  is a recognised complication of mechanical ventilation that can occur in any patient receiving mechanical ventilation, but is most commonly associated with acute respiratory distress syndrome. 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). As an indicator of transalveolar pressure, which predicts alveolar distention, plateau pressure or peak airway pressure (PAP) may be the most effective predictor of risk, but there is no generally accepted safe pressure at which there is no risk. Risk also appears to be increased by aspiration of stomach contents and pre-existing disease such as necrotising pneumonia and chronic lung disease. Status asthmaticus is a particular problem as it requires relatively high pressures to overcome bronchial obstruction. When lung tissues are damaged by alveolar over-distension, the injury may be termed volutrauma, but volume and transpulmonary pressure are closely related. Ventilator induced lung injury is often associated with high tidal volumes (Vt). Use of a hyperbaric chamber Patients undergoing hyperbaric oxygen therapy must equalize their ears to avoid<unk> . High risk of otic<unk>  is associated with unconscious patients.
Barotrauma
Blast injury
Polytrauma
Rheotrauma
Penetrating trauma
Microtrauma
Trauma
Blunt trauma