Air embolism is a rare but potentially lethal adverse event caused by certain medical and surgical procedures. It is considered a preventable event that can cause catastrophic injury, is a serious reportable event and costs related to its treatment are not paid by Medicare and Medicaid. The Pennsylvania Patient Safety Authority, did a 7 year review and found 74 air embolism injuries. The majority of these air embolism injuries resulted from central venous catheters and access devices. The ubiquitous use of central venous catheters when combined with the high mortality rate associated with air embolus requires that hospitals pay special attention to the processes and procedures for their use.
Air embolism occurs when there is a direct connection between a source of air and the blood stream and there is a pressure gradient that allows air to flow into the vascular system. Air can enter when active injection pushes it into the blood or can be passive when the pressure of the venous system is less than the pressure in the intravenous tubing system. Except in cases of trauma and decompression syndrome, most cases occur as a result of medical procedures. Surgical procedures performed in the upright position are particularly prone to create situations where air enters the blood stream. Other causes are intravascular catheterization, radiological procedures especially when an automatic contrast injector is used and positive pressure ventilation.
The resultant injury depends on the amount of air, the rate of entry and whether the air is introduced into the venous or the arterial system. The body can generally tolerate small amounts of air when introduced into the venous system at a slow rate, but large volumes of air into the venous system create a pulmonary embolus that causes circulatory collapse and death. Small amounts of air introduced into the arterial system are generally not tolerated without tissue death including stroke when air bubbles lodge in end arterioles. A detailed review of the medical record is required when a suspected air embolism injury occurs, and lessons need to be learned to prevent what should be a preventable event from happening again.