Cause of Device-Related Incident
Device factors; User errors

Clinical Specialty or Hospital Department
Anesthesia; Cardiology / Cardiac Catheterization; CCU / ICU / NICU; Clinical/Biomedical Engineering; Nursing; Obstetrics and Gynecology; OR / Surgery; Pharmacy / IV therapy

Device Factors
Design / labeling error; Failure of accessory

Document Type
Hazard Reports

External Factors
*Not stated

Mechanism of Injury or Death
Embolism (gaseous or particulate)

Support System Failures
*Not stated

Tampering and/or Sabotage
*Not stated

User Errors
Accidental misconnections; Failure to perform pre-use inspection

UMDNS
Catheters, Central Venous [10-729]

Air Embolism through Central Venous Catheters



Hazard [Health Devices Dec 1985;14(14):436-7]

Problem

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.

Recommendations

  1. Alert all clinical personnel who use central venous catheters to this report and ensure that the risks of catheter disconnections are well understood.
  2. Where possible, use Luer-lock, rather than Luer-taper, connectors for all central venous catheter connections.
  3. 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.
  4. Tape a loop of tubing at the insertion site for strain relief.
  5. When inserting or changing a catheter, put the patient in the Trendelenburg position.
  6. 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.

Notes

  1. 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.
  2. 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.
  3. Kashuk JL, Penn I. Air embolism after central venous catherterization. Surg Gyn Obstet 1984; 159(Sep):249-52
  4. Peters JL. Current problems in central venous catheter systems (Editorial). Intensive Care Med 1982;8(Aug): 205-8.
  5. Peters JL, Armstrong R. Air embolism occurring as a complication of central venous catheterization. Ann Surg 1978;187(Apr):375-8.
  6. Jacobsen WK, Briggs BA, Mason LJ. Paradoxical air embolism as a complication of central venous catheterization. Crit Care Med 1983;11(May):388-9.
  7. Kashuk JL, Penn I. Supra note 3.
  8. Ostrow LS. Air embolism and central venous lines. Am J Nurs 1981;(Nov):2036-8.
  9. Coppa GF, Gouge TH, Hofstetter SR. Supra note 1.
  10. Lambert MJ. air embolism in central venous catheterization: Diagnosis, treatment, and prevention. South Med J 1982;(Oct):1189-91.

UMDNS Term

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

Embolism (gaseous)


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