Air Embolism through Central Venous Catheters
Hazard [Health Devices Dec 1985;14(14):436-7]
ECRI investigated an incident in which an air embolism developed after the
male Luer taper (also known as a Luer slip) connector of a central venous catheter was
inadvertently disconnected from an IV filter. The patient was receiving intravenous
hyperalimentation, also known as total parenteral nutrition (TPN), through a subclavian
(central venous) infusion site; the connector was secured with tape. While the patient was
being assisted from a bedside commode, the catheter disconnected from the IV filter, and
the patient immediately became unresponsive. The patient suffered neurologic damage and
became numb in her left arm and leg.
Many fatal instances of air emboli in
patients with central venous catheters have been reported in the
literature.(1,2,3,4,5) They frequently occur when
the tubing becomes tangled while a patient is getting out of bed, causing the catheter to
disconnect. Although less common, cracks in the catheter hub can also allow air to enter
the venous system.
Central venous catheters are also used in applications other than TPN.
These include central venous pressure monitoring, rapid infusion of fluids, pulmonary
arterial pressure monitoring using Swan-Ganz catheters, and hemodialysis. Also, a central
venous catheter is often placed in the right atrium during surgery to remove air that
might be introduced elsewhere in the venous system. It is possible for an air embolism to
develop during all of these central venous applications.
An air embolism can develop when the right side of the heart is open to
outside air through a disconnected catheter and a negative intrathoracic pressure is
present, such as during inspiration. The right side of the heart is open to outside air
when the catheter is first inserted and during catheter changes. The path to outside air
can also be opened accidentally in three ways: if the Luer taper fitting disconnects and
becomes tangled in the tubing when the patient gets out of bed or rolls over; if the
stopcock is placed in the wrong position; or if there is a crack in the hub of the
catheter. When the path to the outside is open, the negative intrathoracic pressure
generated by respiration can draw air into the right side of the heart through the
catheter. The air passes through the pulmonary artery and, if the bubble is large enough,
may cause a pulmonary infarction.
However, air can also pass to the left side of the heart. Emboli can then
develop in the arterial system, possibly causing a myocardial infarction or stroke. An
estimated 20 to 25% of the population may have a patent foramen ovale (opening between the
left and right atrium).(6) This usually remains closed because the left atrial pressure is
higher than the right atrial pressure. However, air bubbles can pass through the patent
foramen ovale in the following circumstances: if the right atrium is lower than the left
because of body position; if there is turbulence in the atria; or during the use of
intermittent positive pressure ventilation (IPPV) or positive end-expiratory pressure
(PEEP), which raises pulmonary—and therefore right heart—pressure. Left heart
pressure is not raised correspondingly because of the pressure drop across the
capillaries. This pressure gradient causes the air to move to the left side of the heart.
Although the maximum safe amount of air is
unknown, it has been estimated from studies with dogs that as little as 20
mL/sec of air will be associated with symptoms of air emboli, and 70 to 150
mL/sec of air can be fatal.(7,8) Various retrospective clinical studies
show that air embolism due to catheter disconnection has a mortality rate
between 29 and 43%.(9,10) However, any air entering the left side of the heart may
enter the cerebral or coronary circulation and result in dangerous air emboli. We believe
that this risk has been generally unappreciated. In addition to the risk of developing an
air embolism, IV disconnection increases the risk of infection and may result in
significant blood loss, especially in neonates and infants.
ECRI's investigation of the disconnection incident mentioned above
indicates that the Luer taper connector is unreliable, especially in view of the serious
complications that can arise from disconnection. The IV set tubing is usually looped and
taped to the patient to provide strain relief and to secure the assembly to the patient.
These precautions help prevent patient movement from causing a disconnection. Our
investigation shows, however, that taping alone is unreliable because the tape tends to
get wet and become loose.
ECRI strongly recommends the use of Luer-lock, rather than Luer-taper,
connectors for all central venous catheters. At least three other sources in the
literature have made a similar recommendation or have stated that they are using Luer-lock
connectors exclusively following an incident.
Resistance to the use of Luer-lock fittings stems from reports of catheter
disruption during connection and from their being too bulky to allow comfortable dressing
of the IV site. They are also more expensive. However, we believe that when they are
properly applied, Luer-locks are more reliable, and the increased cost is justified.
- Alert all clinical personnel who use central venous
catheters to this report and ensure that the risks of catheter
disconnections are well understood.
- Where possible, use Luer-lock, rather than
Luer-taper, connectors for all central venous catheter connections.
- Inspect all catheter hubs for hairline cracks when
attaching the catheter and redressing the insertion site. Immediately
replace any catheters or IV tubing connectors that leak.
- Tape a loop of tubing at the insertion site for
- When inserting or changing a catheter, put the
patient in the Trendelenburg position.
- When infusing fluid through a central venous line, use an infusion pump
or controller with an air-in-line detector or other protective mechanism to
detect air embolism.
- Coppa GF, Gouge TH, Hofstetter SR. Air embolism: A lethal but
preventable complication of subclavian vein cateterization. J Prevent
Enteral Nutr 1981;5(Apr):166-8.
- Eisenhauer ED, Derveloy RJ, Hastings PR. Prospective evaluation of
central venous pressure (CVP) catheters in a large city-county hospital.
Ann Surg 1982;196(Nov):560-4.
- Kashuk JL, Penn I. Air embolism after central venous catherterization.
Surg Gyn Obstet 1984;
- Peters JL. Current problems in central venous catheter systems
(Editorial). Intensive Care Med 1982;8(Aug): 205-8.
- Peters JL, Armstrong R. Air embolism occurring as a complication of
central venous catheterization. Ann Surg 1978;187(Apr):375-8.
- Jacobsen WK, Briggs BA, Mason LJ. Paradoxical air embolism as a
complication of central venous catheterization. Crit Care Med
- Kashuk JL, Penn I. Supra note 3.
- Ostrow LS. Air embolism and central venous lines. Am J Nurs
- Coppa GF, Gouge TH, Hofstetter SR. Supra note 1.
- Lambert MJ. air embolism in central venous catheterization: Diagnosis,
treatment, and prevention. South Med J 1982;(Oct):1189-91.
Catheters, Central Venous [10-729]
Cause of Device-Related Incident
Device factors: Design/labeling error; failure of accessory
User errors: Accidental misconnection; Failure to perform pre-use inspection
Mechanism of Injury or Death