Symptomatic cerebral air embolism during neuro-angiographic procedures: incidence and problem avoidance.

BACKGROUND: While clinically symptomatic cerebral air embolism secondary to neuro-angiographic procedures is rare, the incidence in a large series of procedures is unknown. Understanding this complication's frequency and etiology is critical if systems are to be instituted to reduce its incidence.
METHODS: We prospectively reviewed 4,568 consecutive neuro-angiographic procedures performed between June 2000 and July 2005. The occurrence and etiology of a symptomatic air embolus was noted, and an incidence was calculated for all procedures and for diagnostic arteriograms and interventional procedures individually.
RESULTS: Four symptomatic cerebral arterial air emboli occurred in 4,568 neuro-angiographic procedures over the five-year period (0.08%). No events occurred in 3,150 diagnostic angiograms while four occurred during 1,418 interventional procedures (0.2%). Two cases occurred during aneurysm coiling embolization (2/548; 0.4%); one case occurred during a carotid stent placement (1/138; 0.7%); one occurred during an internal carotid artery balloon occlusion test (1/73; 1.3%). Three of these complications resulted in permanent neurologic deficits while one resulted in a transient neurologic change that cleared within 60 min of onset. Sources for the emboli included the pressurized arterial flush lines connected to internal carotid artery catheters (three cases) and sudden hypotension with air subsequently entering the internal carotid artery catheter (one case). Two patients were treated with hyperbaric oxygen therapy.
CONCLUSION: Symptomatic cerebral air embolism is a rare event during neuro-angiographic procedures. Analysis of the etiologies of this infrequent event may permit us to further reduce its incidence.