Venous air embolism retrieval catheters cannot capture bubbles; an air lock is required.

Differently designed right atrial venous air embolism retrieval catheters were tested in vitro in clinical simulations to determine if increasing numbers of aspirating orifices enhance the recovery of air bubbles by aspirating through these catheters. Air bubbles of 1.5 to 2.0 mm diameter were directly observed to pass against the aspirating orifices while catheters were vertically suspended in a 3.7 cm diameter glass cylinder filled with hetastarch. Essentially, no air, only fluid, was recovered by any of these submerged catheters upon aspiration. Only when an orifice was positioned above a fluid level could air be retrieved.