|Barotrauma, otitic & Barotrauma, sinus|
|Classification and external resources|
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, but can also be caused by a shock wave. Whales and dolphins are also vulnerable to barotrauma if exposed to rapid and excessive changes in diving pressures.
- 1 Types of injury
- 2 Diving barotrauma
- 3 Blast induced barotrauma
- 4 Ventilator induced barotrauma
- 5 Industry-related barotrauma in animals
- 6 See also
- 7 References
Types of injury
Examples of organs or tissues easily damaged by barotrauma are:
- middle ear (barotitis or aerotitis)
- paranasal sinuses (causing Aerosinusitis)
- eyes (the unsupportive 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 complications of P-valve use) 
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 and 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 either by tight fitting diving equipment or ear wax. Inner ear barotrauma (IEBT) though much less common than MEBT shares a similar mechanism. Mechanical trauma to the inner ear can lead to varying degrees of conductive and sensorineural hearing loss as well as vertigo. It is also common for conditions affecting the inner ear to result in auditory hypersensitivity.
Lung pressure damage in scuba divers 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 breathes out. The lungs do not sense pain when over-expanded giving the diver little warning to prevent the injury. This does not affect breath-hold skin divers as they bring a lungful of air with them from the surface, which merely re-expands safely to near its original volume on ascent. The problem only arises if a breath of compressed gas is taken at depth, which will then expand on ascent to more than the lung volume. Pulmonary barotrauma may also be caused by explosive decompression of a pressurised aircraft.
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 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. Besides tissue rupture, the overpressure may cause ingress of gases into the tissues and further afield through venous blood vessels.
Breathing gas at depth from underwater breathing equipment results in the lungs containing gas at a higher pressure than atmospheric pressure. So a free-diving 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 breathes 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.
Avoidance and treatment
Diving barotrauma can be avoided by eliminating any pressure differences acting on the tissue or organ by equalizing the pressure. There are a variety of techniques:
- The air spaces in the ears, and the sinuses. The risk is burst eardrum. Here, the diver can use a variety of methods, to let air into the middle ears via the Eustachian tubes. Sometimes swallowing will open the Eustachian tubes and equalise the ears.
- The lungs. The risk includes pneumothorax, arterial gas embolism, and mediastinal and subcutanous emphysemas. which are commonly called burst lung or lung overpressure injury by divers. To equalise, all that is necessary is not to hold the breath during ascent. This risk does not arise when snorkel diving from the surface, unless the snorkeller breathes from a high pressure gas source underwater, or from submerged air pockets. Some people have pathologies of the lung which prevent rapid flow of excess air though the passages, which can lead to lung barotrauma even if the breath is not held during rapid depressurisation. These people should not dive as the risk is unacceptably high. Most commercial or military diving medical examinations will look specifically for signs of this pathology.
- The air inside the usual eyes-and-nose diving mask (also known as a half mask). The main risk is bleeding around the eyes from the negative pressure or orbital emphysema from higher pressures. Here, let air into the mask through the nose. Do not dive in eyes-only goggles as sometimes seen on land with industrial breathing sets.
- Air spaces inside a dry suit. The main risk is folds of skin getting pinched inside folds of the drysuit. Most modern drysuits have a tube connection to feed air in from the cylinder. Air must be injected on the descent and vented on the ascent.
Following barotrauma of the ears or lungs from diving the diver should not dive again until thoroughly cleared by a doctor, which can take many months. 
Use of a hyperbaric chamber. Patients undergoing hyperbaric oxygen therapy must learn to equalize in order to avoid barotrauma. Some patients may be at greater risk of otic barotrauma than others.
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.
On study of a panda (hanna), the effects of barotrauma has also been researched in animals.
Ventilator induced barotrauma
Mechanical ventilation can lead to barotrauma 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.
Whales and dolphins suffer severely disabling barotrauma when exposed to excessive pressure changes induced by navy sonar, oil industry airguns, explosives, undersea earthquakes and volcanic eruptions.[unreliable source?]
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.
Swim bladder overexpansion
Fish with isolated swim bladders are susceptible to barotrauma of ascent when brought to the surface by fishing. The swim bladder is an organ of buoyancy control which is filled with gas from the blood, and which is normally removed by the reverse process. If the fish is brought upwards in the water column faster than the gas can be resorbed, the gas will expand until the bladder is stretched to its elastic limit, and may rupture. Barotrauma could be fatal, but rockfish are able to recover if they are sent back to depths of about 45 meters, shortly after surfacing. Scientists at NOAA developed the Seaqualizer to quickly return rockfish to depth. The device could increase survival in caught-and-released rockfish.
- Alternobaric vertigo
- Bell's Palsy
- Dental barotrauma
- Diving hazards and precautions
- Jet ventilation
- Uncontrolled decompression
- US Navy Diving Manual, 6th revision. United States: US Naval Sea Systems Command. 2006. Retrieved 2008-05-26.
- Brubakk, A. O.; T. S. Neuman (2003). Bennett and Elliott's physiology and medicine of diving, 5th Rev ed. United States: Saunders Ltd. p. 800. ISBN 0-7020-2571-2.
- Deafwhale Society (deafwhale.com)
- Richard O. Reinhart (1996). Basic Flight Physiology. McGraw-Hill Professional. ISBN 0-07-052223-5. Retrieved 2008-09-01.
- Fitzpatrick DT, Franck BA, Mason KT, Shannon SG (1999). "Risk factors for symptomatic otic and sinus barotrauma in a multiplace hyperbaric chamber". Undersea and Hyperbaric Medicine 26 (4): 243–7. PMID 10642071. Retrieved 2008-05-23.
- Fiesseler FW, Silverman ME, Riggs RL, Szucs PA (2006). "Indication for hyperbaric oxygen treatment as a predictor of tympanostomy tube placement". Undersea and Hyperbaric Medicine 33 (4): 231–5. PMID 17004409. Retrieved 2008-05-23.
- Klokker M, Vesterhauge S, Jansen EC (November 2005). "Pressure-equalizing earplugs do not prevent barotrauma on descent from 8000 ft cabin altitude". Aviat Space Environ Med 76 (11): 1079–82. PMID 16313146. Retrieved 2008-06-05.
- Broome JR, Smith DJ (November 1992). "Pneumothorax as a complication of recompression therapy for cerebral arterial gas embolism". Undersea Biomedical Research 19 (6): 447–55. PMID 1304671. Retrieved 2008-05-23.
- Nicol E, Davies G, Jayakumar P, Green ND (April 2007). "Pneumopericardium and pneumomediastinum in a passenger on a commercial flight". Aviat Space Environ Med 78 (4): 435–9. PMID 17484349. Retrieved 2008-06-05.
- Butler FK, Gurney N (2001). "Orbital hemorrhage following face-mask barotrauma". Undersea and Hyperbaric Medicine 28 (1): 31–4. PMID 11732882. Retrieved 2008-07-06.
- http://www.ajnr.org/cgi/reprint/26/5/1218.pdf Barotrauma Presenting as Temporal Lobe Injury Secondary to Temporal Bone Rupture - AJNR Am J Neuroradiol 26:1218–1219, May 2005
- Robichaud R, McNally ME (January 2005). "Barodontalgia as a differential diagnosis: symptoms and findings". J Can Dent Assoc 71 (1): 39–42. PMID 15649340. Retrieved 2008-07-19.
- Rauch JW (1985). "Barodontalgia--dental pain related to ambient pressure change". Gen Dent 33 (4): 313–5. PMID 2863194.
- Zadik Y (August 2006). "Barodontalgia due to odontogenic inflammation in the jawbone". Aviat Space Environ Med 77 (8): 864–6. PMID 16909883. Retrieved 2008-07-16.
- Zadik Y, Chapnik L, Goldstein L (June 2007). "In-flight barodontalgia: analysis of 29 cases in military aircrew". Aviat Space Environ Med 78 (6): 593–6. PMID 17571660. Retrieved 2008-07-16.
- Yehuda Zadik (April 2009). "Barodontalgia". J Endod 35 (4): 481–5. doi:10.1016/j.joen.2008.12.004. PMID 19345791. Retrieved 2009-06-01.
- Zadik Y; Einy, S; Pokroy, R; Bar Dayan, Y; Goldstein, L (June 2006). "Dental Fractures on Acute Exposure to High Altitude". Aviat Space Environ Med 77 (6): 654–7. PMID 16780246. Retrieved 2008-07-16.
- Zadik, Yehuda (January 2009). "Aviation dentistry: current concepts and practice" (PDF). British Dental Journal 206 (1): 11–6. doi:10.1038/sj.bdj.2008.1121. PMID 19132029. Retrieved 2009-01-26.
- Zadik, Yehuda; Drucker Scott (September 2011). "Diving dentistry: a review of the dental implications of scuba diving". Aust Dent J. 56 (3): 265–71. doi:10.1111/j.1834-7819.2011.01340.x. PMID 21884141.
- Harris, Richard (December 2009). "Genitourinary infection and barotrauma as complications of 'P-valve' use in drysuit divers". Diving and Hyperbaric Medicine : the Journal of the South Pacific Underwater Medicine Society 39 (4): 210–2. PMID 22752741. Retrieved 2013-04-04.
- Marx, John (2010). Rosen's emergency medicine: concepts and clinical practice 7th edition. Philadelphia, PA: Mosby/Elsevier. p. 1906. ISBN 978-0-323-05472-0.
- Marx, John (2010). Rosen's emergency medicine: concepts and clinical practice 7th edition. Philadelphia, PA: Mosby/Elsevier. p. 1907. ISBN 978-0-323-05472-0.
- Bolognini A, Delehaye E, Cau M, Cosso L (2008). "Barotraumatic orbital emphysema of rhinogenic origin in a breath-hold diver: a case report". Undersea and Hyperbaric Medicine 35 (3): 163–7. PMID 18619111. Retrieved 2009-08-07.
- Life effects of Barotrauma at the American Hearing Research Foundation
- Lehm Jan P, Bennett Michael H (2003). "Predictors of middle ear barotrauma associated with hyperbaric oxygen therapy". South Pacific Underwater Medicine Society Journal 33: 127–133. Retrieved 2009-07-15.
- Torkki, Markus; Virve Koljonen; Kirsi Sillanpää1; Erkki Tukiainen; Sari Pyörälä; Esko Kemppainen; Juha Kalske; Eero Arajärvi; Ulla Keränen; Eero Hirvensalo (August 2006). "Triage in a Bomb Disaster with 166 Casualties". European Journal of Trauma 32 (4): 374–80. doi:10.1007/s00068-006-6039-8.
- Kenneth Gabriel Williams (1959). The New Frontier: Man's Survival in the Sky. Thomas. Retrieved 2008-07-28.
- Bason R, Yacavone DW (May 1992). "Loss of cabin pressurization in U.S. Naval aircraft: 1969-90". Aviat Space Environ Med 63 (5): 341–5. PMID 1599378.
- Barotrauma Causes Whales to Mass Beach Themselves!
- Danil, K, and J.A. St.Leger. "Seabird and Dolphin Mortality Associated with Underwater Detonation Exercises." Marine Technology Society Journal 45, no. 6 (2011): 89-95. http://swfsc.noaa.gov/uploadedFiles/Divisions/PRD/Programs/Photogrammetry/Danil%20%20St.%20Leger%202011.pdf
- The Times, 26 August 2008, Wind farms cause thousands of bats to die from trauma