Air embolism 447738 224603604 2008-07-09T16:46:56Z 140.254.45.27 /* Treatment */ {{Infobox_Disease | Name = {{PAGENAME}} | Image = | Caption = | DiseasesDB = 313 | ICD10 = {{ICD10|O|88|0|o|85}}, {{ICD10|T|79|0|t|79}} | ICD9 = {{ICD9|673.0}}, {{ICD9|999.1}} | ICDO = | OMIM = | MedlinePlus = | eMedicineSubj = emerg | eMedicineTopic = 787 | MeshID = D004618 | }} An '''air embolism''', or more generally '''gas embolism''', is a medical condition caused by [[gas]] bubbles in the bloodstream (''embolism'' in a medical context refers to any large moving mass or defect in the blood stream). Small amounts of air often get into the blood circulation accidentally during surgery and other medical procedures, but most of these in veins are stopped at the lungs, and a venous air embolism that shows [[symptom]]s are very rare. Death may occur if a large bubble of gas becomes lodged in the heart, stopping blood from flowing from the right [[Ventricle (heart)|ventricle]] to the [[lungs]] (this is similar to [[vapor lock]] in engine fuel systems). However, the amount of gas necessary for this to happen is quite variable, and also depends on a number of other factors, such as body position. Gas embolism into an artery, termed [[arterial gas embolism]], or AGE, is a more serious matter than in a vein, since a gas bubble in an artery may directly cause stoppage of blood flow to an area fed by the artery. The symptoms of AGE depend on the area of blood flow, and may be those of [[stroke]] or [[myocardial infarction|heart attack]] if the brain or heart, respectively, are affected. ==Pathogenesis== Air embolism can occur whenever a blood vessel is open and a pressure gradient exists favoring entry of gas. Because the pressure in most arteries and veins is greater than atmospheric pressure, an air embolus does not always happen when a blood vessel is injured. In the veins above the heart, such as in the head and neck, the pressure is less than atmospheric and an injury may let air in. This is one reason why [[surgery|surgeon]]s must be particularly careful when operating on the [[brain]], and why the head of the bed is tilted down when inserting or removing a [[central venous catheter]] from the [[jugular vein|jugular]] or [[subclavian vein]]s. When air enters the veins, it travels to the right side of the heart, and then to the lungs. This can cause the vessels of the lung to constrict, raising the pressure in the right side of the heart. If the pressure rises high enough in a patient who is one of the 20% to 30% of the population with a [[patent foramen ovale]], the gas bubble can then travel to the left side of the heart, and on to the brain or [[coronary circulation|coronary arteries]]. Such bubbles are responsible for the most serious of gas embolic symptoms. [[physical trauma|Trauma]] to the lung can also cause an air embolism. This may happen after a patient is placed on a [[ventilator]] and air is forced into an injured vein or artery, causing sudden death. Breath-holding while ascending from [[scuba diving]] may also force lung air into pulmonary arteries or veins in a similar manner, due to the pressure difference. Air can be injected directly into the veins either accidentally or as a deliberate act. Examples include misuse of a [[syringe]], and [[industrial injury]] resulting from use of [[compressed air]]. However, the amount of air that would be administered by a single small syringe is, in most cases, not enough suddenly stop the heart, nor cause instant death. Single air bubbles in a vein do not stop the heart, due to being too small.{{Fact|date=December 2007}} However, such bubbles may occasionally reach the arterial system through a [[patent foramen ovale]], as noted above, and cause random [[ischemic]] damage, depending on their route of arterial travel. ===Gas embolism in diving=== '''Gas embolism''' is one of the [[diving disorders]] [[Scuba diving|SCUBA divers]] sometimes suffer when they receive [[barotrauma|pressure damage]] to their lungs following a rapid ascent where the breath is inappropriately held against a closed [[glottis]], allowing pressure to build up inside the lungs, relative to the blood. It is termed "gas" because the diver may be using a diving [[breathing gas]] other than [[air]]. The gas bubbles can impede the flow of oxygen-rich blood to the brain and vital organs. They can also cause [[clot]]s to form in [[blood]] vessels. Gas embolism and [[decompression sickness]] (DCS) may be difficult to distinguish, as they may have similar symptoms, especially in the [[central nervous system]]. The treatment for both, up to point of hospitalization, is the same, because they are both the result of gas bubbles in the body. In a diving context, the two are often called [[decompression illness]] (DCI). ==Treatment== Recompression is the most effective treatment of an air embolism.<ref>{{cite web |url=http://www.uhms.org/ResourceLibrary/Indications/AirorGasEmbolism/tabid/271/Default.aspx |title=Air or Gas Embolism |author=Undersea and Hyperbaric Medical Society |accessdate=2008-05-19 }}</ref> Normally this is carried out in a [[recompression chamber]]. This is because as pressure increases, the solubility of a gas increases. Additionally, owing to Boyle's law, the size of the gas bubble or bubbles decreases in proportion to the increase in atmospheric pressure. In the hyperbaric chamber the patient breathes 100% oxygen. Under hyperbaric conditions, oxygen diffuses into the bubbles, displacing the nitrogen from the bubble and into solution in the blood. Oxygen bubbles are more easily tolerated. Air is composed of 21% oxygen and 78% nitrogen with trace amounts of other gases. Additionally, diffusion of oxygen into the blood and tissues under hyperbaric conditions supports areas of the body which are deprived of blood flow when arteries are blocked by gas bubbles. This helps to reduce ischemic injury. Finally, the effects of hyperbaric oxygen antagonize leukocyte-medicated ischemic-reperfusion injury. [[Oxygen first aid]] treatment is useful for suspected gas embolism casualties or divers who have made fast ascents or missed decompression stops.<ref name=Longphre>{{cite journal |last=Longphre |first=J. M. |coauthors=P. J. DeNoble; R. E. Moon; R. D. Vann; J. J. Freiberger |title=First aid normobaric oxygen for the treatment of recreational diving injuries. |journal=Undersea Hyperb Med. |volume=34 |issue=1 |pages=43-49 |date=[[2007]] |issn=1066-2936 |oclc=26915585 |pmid=17393938 |url=http://archive.rubicon-foundation.org/5514 |accessdate=2008-05-30 }}</ref> Most fully closed-circuit [[rebreather]]s can deliver sustained high concentrations of oxygen-rich [[breathing gas]] and could be used as an alternative to pure [[open-circuit]] oxygen [[resuscitator]]s. ==Pop culture== In season 4, episode 15 of [[House (TV series)|House]], a bus driver had an air embolism from dental surgery. During the hospital scene in the 2006 re-make of The Omen, Katherine Thorn (played by actress Julia Stiles) has a lethal amount of oxygen injected into her IV (by her son's babysitter) giving her an air embolism followed by almost instantaneous cardiac arrest, killing her. In the film Apt Pupil, the Nazi war criminal commits suicide in the hospital by intentionally blowing air into his IV line. In the film The Ring Two when the psychiatric doctor tells Aiden (who is possessed by Samara, the girl who died in the well) that he cannot go home, he "shows" the doctor something by some means of mental projection, that makes her inject herself with a full syringe of air. In an episode of [[The Simpsons]] Homer is injected with a syringe full of air, after which he passes out. ==External links== * [http://www.scuba-doc.com/artgsemb.htm Arterial Gas Embolism] {{Pathology of pregnancy, childbirth and the puerperium}} {{Consequences of external causes}} [[Category:Diving medicine]] [[Category:Medical emergencies]] [[de:Luftembolie]] [[it:Embolia gassosa arteriosa]] [[pl:Zator gazowy]] [[pt:Aeroembolismo]] [[ru:Газовая эмболия]] [[tr:Hava ambolisi]]