Venous air embolism may arise from 4 possible areas of air entry into the dialysis circuit

Schematic diagram of a hemodialysis circuit depicting four possible areas of air entry. (1) A broken or loose luer connection between the arterial needle and the tubing can result in air entry because this segment has negative intraluminal pressure. (2) A hole or break in the arterial tubing can suck air into the arterial line. (3) Air can be injected inadvertently while administering an anticoagulant or saline. (4) Inadequate priming can result in air entry from the dialyzer or dialysis tubing. A crack in the venous bloodline will not result in air entry because it has positive intraluminal pressure. Air entering the circuit presents to the venous air trap and forms foam or bubble at the top of the blood level. When the blood level in the venous air trap chamber falls below the level of the air detector, an alarm is triggered and blood flow is automatically stopped.