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.
|Other names||Squeeze, Decompression illness, Lung overpressure injury|
|Mild barotrauma to a diver caused by mask squeeze|
|Specialty||Emergency medicine, occupational medicine, hyperbaric medicine |
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 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 (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.
Examples of organs or tissues easily damaged by barotrauma are:
- Middle ear (barotitis or aerotitis)
- Paranasal sinuses (causing aerosinusitis)
- 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 complications of P-valve use)
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 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 the circulatory system. This pulmonary barotrauma (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 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. 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.
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.
Barotrauma 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 barotrauma. High risk of otic barotrauma is associated with unconscious patients.
In terms of barotrauma the diagnostic workup for the affected individual would include the following:
- Creatine kinase (CPK) level: Increases in CPK levels indicate tissue damage associated with decompression sickness.
- Complete blood count (CBC)
- Arterial blood gas (ABG) determination
- Chest radiography can show pneumothorax, and is indicated if there is chest discomfort or breathing difficulty
- 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. It can be used where barotrauma-related pneumothorax is suspected and chest radiograph findings are negative.
- Echocardiography can be used to detect 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 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.
A problem mostly of historical interest, but still relevant to surface supplied divers who dive with the helmet sealed to the dry suit. If the air supply hose is ruptured near or above the surface, the pressure difference between the water around the diver and the air in the hose can be several bar. The non-return valve at the connection to the helmet will prevent backflow if it is working correctly, but if absent, as in the early days of helmet diving, or if it fails, the pressure difference will tend to squeeze the diver into the rigid helmet, which can result in severe trauma. The same effect can result from a large and rapid increase in depth if the air supply is insufficient to keep up with the increase in ambient pressure.
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. The lungs do not sense pain when over-expanded giving the diver little warning to prevent the injury. This does not affect breath-hold 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 ambient pressure gas is taken at depth, which may then expand on ascent to more than the lung volume. Pulmonary barotrauma may also be caused by explosive decompression of a pressurised aircraft.
Barotrauma may be caused when diving, either from being crushed, or squeezed, on descent or by stretching and bursting on ascent; both can be avoided by equalising the pressures. A negative, unbalanced pressure is known as a squeeze, crushing eardrums, dry suit, lungs or mask inwards and can be equalised by putting air into the squeezed space. A positive unbalanced pressure expands internal spaces rupturing tissue and can be equalised by letting air out, for example by exhaling. Both may cause barotrauma. There are a variety of techniques depending on the affected area and whether the pressure inequality is a squeeze or an expansion:
- Ears and sinuses: There is a risk of stretched or burst eardrums, usually crushed inwards during descent but sometimes stretched outwards on ascent. The diver can use a variety of methods to let air into or out of the middle ears via the Eustachian tubes. Sometimes swallowing will open the Eustachian tubes and equalise the ears.
- Lungs: There is a risk of pneumothorax, arterial gas embolism, and mediastinal and subcutanous emphysemas during ascent, which are commonly called burst lung or lung overpressure injury by divers. To equalise the lungs, all that is necessary is not to hold the breath during ascent. This risk does 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. Some people have pathologies of the lung which 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. 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.
- Diving mask squeeze enclosing the eyes and nose: The main risk is 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. This can be avoided by breathing air into the mask through the nose. Goggles covering only the eyes are not suitable for deep diving as they cannot be equalised.
- Dry suit squeeze. The main risk is skin getting pinched and bruised by folds of the dry suit when squeezed on descent. Most dry suits can be equalised against squeeze via a manually operated valve fed from a low pressure gas supply. Air must be manually injected during the descent to avoid squeeze and is manually or automatically vented on the ascent to maintain buoyancy control.
- Diving helmet squeeze: Helmet squeeze will occur 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. Severity will depend on the hydrostatic pressure difference. A very rapid descent, usually by accident, may exceed the rate at which the breathing gas supply can equalise the pressure causing a temporary squeeze. The introduction of the non-return valve and high maximum gas supply flow rates have all but eliminated both these risks. In helmets fitted with a neck dam, the dam will admit water into the helmet if the internal pressure gets too low; this is less of a problem than helmet squeeze but the diver may drown if the gas supply is not reinstated quickly.:90 This form of barotrauma is avoidable by controlled descent rate, which is standard practice for commercial divers, who will use shotlines, diving stages and wet bells to control descent and ascent rates.
Professional divers are screened for risk factors during initial and periodical medical examination for fitness to dive. In most cases recreational divers are not medically screened, but are required to provide a medical statement before acceptance for training in which the most common and easy to identify risk factors must be declared. If these factors are declared, the diver may be required to be examined by a medical practitioner, and may be disqualified from diving if the conditions indicate.
Asthma, Marfan syndrome, and COPD pose a very high risk of pneumothorax. In some countries these 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.
A significant part of entry level diver training is focused on understanding the risks and procedural avoidance of barotrauma. Professional divers and recreational divers with rescue training are trained in the basic skills of recognizing and first aid management of diving barotrauma.
In mechanical ventilation
Isolated mechanical forces may not adequately explain ventilator induced lung injury (VILI). The damage is affected by the interaction of these 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. Cyclic deformation of lung tissue may play a large part in the cause of VILI, and contributory factors probably include tidal volume, positive end-expiratory pressure and respiratory rate. There is no protocol guaranteed to avoid all risk in all applications.
Treatment of diving barotrauma depends on the symptoms. Lung over-pressure injury may require a chest drain to remove air from the pleura or mediastinum. Recompression with hyperbaric oxygen therapy is the definitive treatment for arterial gas embolism, as the raised pressure reduces bubble size, low inert gas partial pressure accelerates inert gas solution and high oxygen partial pressure helps oxygenate tissues compromised by the emboli. Care must be taken when recompressing to avoid a tension pneumothorax. 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, assessment of airway, breathing and circulation, neurological assessment, and managing any immediate life-threatening conditions. High-flow oxygen up to 100% is considered appropriate for diving accidents. Large-bore venous access with isotonic fluid infusion is recommended to maintain blood pressure 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 haemothorax
- Foley catheterization may be necessary for spinal cord AGE if the person is unable to urinate.
- Intravenous hydration may be required to maintain adequate blood pressure.
- Therapeutic recompression is indicated for severe AGE. The diving medical practitioner will need to know the vital signs and relevant symptoms, along with the recent pressure exposure and breathing gas history of the patient. Air transport should be below 1,000 feet (300 m) if possible, or in a pressurized aircraft which should be pressurised to as low an altitude as reasonably possible.
Sinus squeeze and middle ear squeeze are generally treated with decongestants to reduce the pressure differential, with anti-inflammatory medications to treat the pain. For severe pain, narcotic analgesics may be appropriate.
Suit, helmet and mask squeeze are treated as trauma according to symptoms and severity.
Barotrauma in animals
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.
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. Bats can suffer fatal barotrauma in the low pressure zones behind the blades of wind turbines due to their more fragile mammalian lung structure in comparison with the more robust Avian lungs, which are less affected by pressure change.
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 extracted from solution in 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 can be directly fatal or disable the fish rendering it vulnerable to predation, but rockfish are able to recover if they are returned to depths similar to those they were pulled up from, 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 – Dizziness resulting from unequal pressures in the middle ears
- Atelectotrauma – Damage caused to the lung by mechanical ventilation
- Barodontalgia – Tooth pain caused by ambient pressure change
- Diving hazards and precautions – List of the hazards to which an underwater diver may be exposed, their possible consequences and the common ways to manage the associated risk
- Dysbarism – Medical conditions resulting from changes of ambient pressure.
- Modes of mechanical ventilation – The methods of inspiratory support
- Rheotrauma – The harm caused to a patient's lungs by high gas flows as delivered by mechanical ventilation
- Weather pains, also known as Meteoropathy – Claims of pain associated with changes in barometric pressure, humidity or other weather phenomena
- Uncontrolled decompression – An unplanned drop in the pressure of a sealed system
- US Navy Diving Manual, 6th revision. United States: US Naval Sea Systems Command. 2006.
- Brubakk, A. O.; Neuman, T. S. (2003). Bennett and Elliott's physiology and medicine of diving, 5th Rev ed. United States: Saunders Ltd. p. 800. ISBN 978-0-7020-2571-6.
- Baerwald, Erin F.; D'Amours, Genevieve H.; Klug, Brandon J.; Barclay, Robert M. R. (26 August 2008). "Barotrauma is a significant cause of bat fatalities at wind turbines". Current Biology. 18 (16): R695–R696. doi:10.1016/j.cub.2008.06.029. OCLC 252616082. PMID 18727900. Lay summary – CBC Radio - Quirks & Quarks (20 September 2008). Laysource includes audio podcast of interview with author.
- Reinhart, Richard O. (1996). Basic Flight Physiology. McGraw-Hill Professional. ISBN 978-0-07-052223-7.
- Fitzpatrick, D. T.; Franck, B. A.; Mason, K. T.; Shannon, S. G. (1999). "Risk factors for symptomatic otic and sinus barotrauma in a multiplace hyperbaric chamber". Undersea and Hyperbaric Medicine. 26 (4): 243–7. PMID 10642071.
- Fiesseler, F. W.; Silverman, M. E.; Riggs, R. L.; Szucs, P. A. (2006). "Indication for hyperbaric oxygen treatment as a predictor of tympanostomy tube placement". Undersea and Hyperbaric Medicine. 33 (4): 231–5. PMID 17004409.
- Klokker, M.; Vesterhauge, S.; Jansen, E. C. (November 2005). "Pressure-equalizing earplugs do not prevent barotrauma on descent from 8000 ft cabin altitude". Aviation, Space, and Environmental Medicine. 76 (11): 1079–82. PMID 16313146. Retrieved 5 June 2008.
- Broome, J. R.; Smith, D. J. (November 1992). "Pneumothorax as a complication of recompression therapy for cerebral arterial gas embolism". Undersea Biomedical Research. 19 (6): 447–55. PMID 1304671.
- Nicol, E.; Davies, G.; Jayakumar, P.; Green, N. D. (April 2007). "Pneumopericardium and pneumomediastinum in a passenger on a commercial flight". Aviation, Space, and Environmental Medicine. 78 (4): 435–9. PMID 17484349. Retrieved 5 June 2008.
- Butler, F. K.; Gurney, N. (2001). "Orbital hemorrhage following face-mask barotrauma". Undersea and Hyperbaric Medicine. 28 (1): 31–4. PMID 11732882.
- Cortes, Maria D. P.; Longridge, Neil S.; Lepawsky, Michael; Nugent, Robert A. (May 2005). "Barotrauma Presenting as Temporal Lobe Injury Secondary to Temporal Bone Rupture" (PDF). American Journal of Neuroradiology. 26: 1218–1219.
- Robichaud, R.; McNally, M. E. (January 2005). "Barodontalgia as a differential diagnosis: symptoms and findings". Journal of the Canadian Dental Association. 71 (1): 39–42. PMID 15649340.
- Rauch, J. W. (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". Aviation, Space, and Environmental Medicine. 77 (8): 864–6. PMID 16909883.
- Zadik, Y.; Chapnik, L.; Goldstein, L. (June 2007). "In-flight barodontalgia: analysis of 29 cases in military aircrew". Aviation, Space, and Environmental Medicine. 78 (6): 593–6. PMID 17571660.
- Zadik, Yehuda (April 2009). "Barodontalgia". Journal of Endodontics. 35 (4): 481–5. doi:10.1016/j.joen.2008.12.004. PMID 19345791.
- Zadik, Y.; Einy, S.; Pokroy, R.; Bar Dayan, Y.; Goldstein, L. (June 2006). "Dental Fractures on Acute Exposure to High Altitude". Aviation, Space, and Environmental Medicine. 77 (6): 654–7. PMID 16780246.
- 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.
- 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. 39 (4): 210–2. PMID 22752741.
- Staff. "Mechanism of Injury for Pulmonary Over-Inflation Syndrome". DAN Medical Frequently Asked Questions. Diver's Alert Network. Retrieved 17 January 2017.
- Torkki, Markus; Koljonen, Virve; Sillanpää1, Kirsi; Tukiainen, Erkki; Pyörälä, Sari; Kemppainen, Esko; Kalske, Juha; Arajärvi, Eero; Keränen, Ulla; Hirvensalo, Eero (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.
- Williams, Kenneth Gabriel (1959). The New Frontier: Man's Survival in the Sky. Thomas.
- Bason, R.; Yacavone, D. W. (May 1992). "Loss of cabin pressurization in U.S. Naval aircraft: 1969–90". Aviation, Space, and Environmental Medicine. 63 (5): 341–5. PMID 1599378.
- Parker JC, Hernandez LA, Peevy KJ (1993). "Mechanisms of ventilator-induced lung injury". Crit Care Med. 21 (1): 131–43. doi:10.1097/00003246-199301000-00024. PMID 8420720.
- Soo Hoo, Guy W (31 December 2015). Mosenifar, Zab (ed.). "Barotrauma and Mechanical Ventilation". Drugs and Diseases – Clinical procedures. Medscape.
- Haake, Ronald; Schlichtig, Robert; Ulstad, David R.; Henschen, Ross R. (April 1987). "Barotrauma: Pathophysiology, Risk Factors, and Prevention" (PDF). Chest. 91 (4): 608–613. doi:10.1378/chest.91.4.608. PMID 3549176. Retrieved 16 January 2017.
- Albaiceta GM, Blanch L (2011). "Beyond volutrauma in ARDS: the critical role of lung tissue deformation". Crit Care. 15 (2): 304. doi:10.1186/cc10052. PMC 3219320. PMID 21489320.
- 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.
- Kaplan, Joseph. Alcock, Joe (ed.). "Barotrauma Workup: Laboratory Studies, Imaging Studies, Other Tests". emedicine.medscape.com. Retrieved 15 January 2017.
- 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.
- Barsky, Steven; Neuman, Tom (2003). Investigating Recreational and Commercial Diving Accidents. Santa Barbara, California: Hammerhead Press. pp. 61, 90. ISBN 978-0-9674305-3-9.
- Staff (29 March 2013). "Aircraft Operations at Altitudes Above 25,000 Feet Mean Sea Level or Mach Numbers Greater Than .75" (PDF). Advisory Circular 61-107B. U.S. Department of Transportation Federal Aviation Administration. p. 36. Retrieved 13 January 2017.
- Kay, E (2000). "Prevention of middle ear barotrauma". Doc's Diving Medicine. staff.washington.edu. Archived from the original on 16 January 2017. Retrieved 13 January 2017.
- Vorosmarti, J.; Linaweaver, P. G., eds. (1987). "Fitness to Dive. 34th Undersea and Hyperbaric Medical Society Workshop". UHMS Publication Number 70(WS-WD)5-1-87. Bethesda, Maryland: Undersea and Hyperbaric Medical Society. Retrieved 13 January 2017.
- 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.
- Barsky, Steven M.; Long, Dick; Stinton, Bob (2006). Dry Suit Diving: A Guide to Diving Dry. Ventura, Calif.: Hammerhead Press. ISBN 9780967430560.
- Staff. "Incidents list". Incidents database. The Divers Association. p. 22. Retrieved 18 May 2017.
- Joint Medical Subcommittee of ECHM and EDTC (24 June 2003). Wendling, Jürg; Elliott, David; Nome, Tor (eds.). Fitness to Dive Standards – Guidelines for Medical Assessment of Working Divers (PDF). pftdstandards edtc rev6.doc (Report). European Diving Technology Committee. Retrieved 18 May 2017.CS1 maint: uses authors parameter (link)
- Richardson, Drew. "The RSTC Medical statement and candidate screening model". South Pacific Underwater Medicine Society (SPUMS) Journal Volume 30 No.4 December 2000. South Pacific Underwater Medicine Society. pp. 210–213.
- Adir, Yochai; Bove, Alfred A. (2016). Yochai Adir and Alfred A. Bove (eds.). "Can asthmatic subjects dive?" (PDF). Number 1 in the Series "Sports-related Lung Disease". European Respiratory Review. 25 (140): 214–220. doi:10.1183/16000617.0006-2016. PMID 27246598. Retrieved 10 June 2016.CS1 maint: uses editors parameter (link)
- Staff (1 October 2004). "Minimum course standard for Open Water Diver training" (PDF). World Recreational Scuba Training Council. pp. 8–9.
- "Diving Regulations 2009". Occupational Health and Safety Act 85 of 1993 – Regulations and Notices – Government Notice R41. Pretoria: Government Printer. Archived from the original on 4 November 2016. Retrieved 3 November 2016 – via Southern African Legal Information Institute.
- Staff (29 October 2009). "International Diver Training Certification: Diver Training Standards, Revision 4" (PDF). Diver Training Standards. Malestroit, Brittany: International Diving Schools Association. Archived from the original (PDF) on 3 March 2016. Retrieved 6 November 2016.
- Stephenson, Jeffrey. "Pathophysiology, treatment and aeromedical retrieval of SCUBA – related DCI". Journal of Military and Veterans' Health. 17 (3). ISSN 1835-1271.
- Kaplan, Joseph. Alcock, Joe (ed.). "Barotrauma Treatment & Management". emedicine.medscape.com. Retrieved 15 January 2017.
- Kaplan, Joseph. Alcock, Joe (ed.). "Barotrauma Treatment & Management: Emergency Department Care". emedicine.medscape.com. Retrieved 15 January 2017.
- Kaplan, Joseph. Alcock, Joe (ed.). "Barotrauma Medication". emedicine.medscape.com. Retrieved 15 January 2017.
- Bentz, Brandon G.; Hughes, C. Anthony (October 2012). "Barotrauma". Hearing and balance disorders. American Hearing Research Foundation. Retrieved 16 January 2017.
- Danil, K; St.Leger, J.A. (2011). "Seabird and Dolphin Mortality Associated with Underwater Detonation Exercises" (PDF). Marine Technology Society Journal. 45 (6): 89–95. doi:10.4031/mtsj.45.6.5.
- "Wind farms cause thousands of bats to die from trauma". The Times. 26 August 2008.
- staff (26 August 2008). "Why Wind Turbines Can Mean Death For Bats". Science news. Science Daily.
- Tripp, Emily (5 November 2012). "Saving Rockfish Stocks One Recompression at a Time". Marine Science Today.