The symptoms may be subtle and not immediately noticeable, and may develop for some time after surfacing. Ventilator induced pulmonary barotrauma
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. Direct injection
Air can be injected directly into a vein or artery accidentally during clinical procedures. Misuse of a syringe to meticulously remove air from the vascular tubing of a hemodialysis circuit can allow air into the vascular system. Venous air embolism is a rare complication of diagnostic and therapeutic procedures requiring catheterization of a vein or artery. If a significant embolism occurs, the cardiovascular, pulmonary, or central nervous system may be affected. Interventions to remove or mitigate the embolism may include procedures to reduce bubble size, or withdrawal of air from the right atrium.The lethal dose for humans is considered theoretically between 3 and 5 ml per kg. It is estimated that 300-500 ml of gas introduced at a rate of 100 ml per sec would prove fatal. Mechanism
Air embolism can occur whenever a blood vessel is open and a pressure gradient exists favoring entry of gas. Because the circulatory pressure in most arteries and veins is greater than atmospheric pressure, an air embolus does not often happen when a blood vessel is injured.
During opening arguments for sentencing, prosecutors told the court that they would present evidence of an additional three murders and three attempted murders.Dorothy L. Sayers made use of direct injection air embolism as a murder method in her 1927 Lord Peter Wimsey mystery novel Unnatural Death (published in the US in 1928 as The Dawson Pedigree), although her description was subsequently criticised as implausible on account of the injection site and volume.Air embolism was the method used by an insane nurse to euthanize seven terminally ill patients in the episode "Amazing Grace" of the TV series Shadow Chasers.Near the end of young adult novel Catching Fire, as well as its film adaptation, protagonist Katniss Everdeen grabs a syringe and fills it with air, with the intention of killing Peeta Mellark quickly via air embolism. In plants
Air embolisms generally occur in the xylem of vascular plants because a fall in hydraulic pressure results in cavitation. Falling hydraulic pressure occurs as a result of water stress or physical damage. A number of physiological adaptations serve to prevent cavitation and to recover from it. The cavitation may be prevented from spreading by the narrow pores in the walls between vessel elements. The plant xylem sap may be able to detour around the cavitation through interconnections. Water loss may be reduced by closing off leaf stomata to reduce transpiration, or some plants produce positive xylem pressure from the roots. When xylem pressure increases, the cavitation gases may redissolve.