Air or Gas Embolism
Gas embolism occurs when gas bubbles enter into the arteries or veins. Arterial gas embolism (AGE) was classically described during submarine escape training, in which pulmonary barotrauma occurred during free ascent after breathing compressed gas at depth. AGE can also occur while SCUBA diving if during rapid ascent to the surface the diver holds their breath. Gas can then enter into the pulmonary vein circulation, return to the systemic circulation and result in intra-arterial gas embolism with resultant manifestations which can include but are not limited to: loss of consciousness, confusion, focal neurological deficits, cardiac arrhythmias or ischemia. Venous gas embolism can also result in similar outcomes if the volume of gas is sufficiently large enough to overwhelm the pulmonary capillary network or by directly entering the left side of the heart via an arterial septal defect or patent foramen ovale.
Causes of gas embolism other than diving related include accidental intravenous air injection, cardiopulmonary bypass accidents, needle biopsy of the lung, hemodialysis, central venous catheter placement or disconnection, gastrointestinal endoscopy, hydrogen peroxide irrigation or ingestion, arthroscopy, cardiopulmonary resuscitation, percutaneous hepatic puncture, blowing air into the vagina during orogenital sex and sexual intercourse after childbirth. Air embolism can occur during procedures in which the surgical site is under pressure (e.g. laparoscopy, transurethral surgery, vitrectomy, endoscopic vein harvesting and hysteroscopy). Massive VGE can occur due to passive entry of air into surgical wounds that are elevated above the level of the heart (such that the pressure in adjacent veins is subatmospheric). This has classically been described in sitting craniotomy but has also occurred during cesarean section, prostatectomy using the radical perineal and retropubic approaches, spine surgery, hip replacement, liver resection, liver transplantation and insertion of dental implants.
Clinical deficits can occur after intra-arterial injection of only small volumes of air. Intravenous injection is often asymptomatic unless larger volumes are infused.
While imaging studies sometimes reveal intravascular air, brain imaging is often normal even in the presence of severe neurological abnormalities. Findings that support the diagnosis of AGE include evidence of pulmonary barotrauma (pnemothorax/pneumomediastinum) and evidence of intravascular gas on radiographic images, ultrasound or direct observation (e.g. aspiration of gas from a central venous line).
Hyperbaric oxygen therapy is recommended in cases of AGE with neurological manifestations. A short interval between embolism and recompression treatment is associated with a higher probability of good outcome.
The above information was obtained from:
Moon RE. Air or Gas Embolism. Hyperbaric Oxygen Therapy Indications, 12th Edition, Undersea and Hyperbaric Medical Society, Durnham, NC; 2008
Long Beach Memorial Medical Center
Department of Hyperbaric Medicine
2801 Atlantic Avenue
Long Beach, California 90806
Telephone: (562) 933-6960
Fax: (562) 933-6060