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Venous Catheter Angiography: Symptoms, Prevention and Treatment of Air Embolism During Placement

September 23, 2009
Written by: , Filed in: Cardiac Imaging
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Air embolism during central venous catheter placement may be fatal despite mild symptoms.

Central venous catheters are frequently placed by interventional radiologists. Careful technique is needed to prevent air embolism, and supplemental oxygen administration is the most effective treatment for air embolism.

While the use of ultrasound and/or fluoroscopy for guidance has improved the safety of central venous catheter placement, complications can and do occur. Air embolism caused by air being pulled into the central venous circulation during the procedure and lodging in the right ventricle or pulmonary artery may result in obstruction to blood flow, and a possible cardiovascular collapse.

A study evaluating the incidence, consequences, and treatment of air embolism occurring during percutaneous placement of central venous catheters appeared in the Journal of Vascular and Interventional Radiology.

A retrospective review of medical records found that 11,583 central venous catheters were placed in the Department of Radiology at the author’s institution over slightly more than five years, with 7,179 catheters being non-tunneled and 4,404 being tunneled.

Of these, 15 patients had an air embolus during the procedure. The mean age of these patients was 58.5 years, with a range of 23 to 90 years. All procedures were performed with conscious sedation.

The authors found that all 15 episodes of air embolization occurred in patients undergoing placement of a tunneled catheter while it was being passed through the peel-away introducer sheath, despite the fact that the sheath was pinched closed following removal of a unidilator.

An air embolus was determined to be present by an audible sound of air entering the catheter or sheath, or by visualization of an air embolism in the heart or pulmonary artery fluoroscopically.

Four patients were asymptomatic and were not treated. Six patients developed mild symptoms, including mild dyspnea, brief decrease in arterial oxygen saturation level, and momentary chest discomfort.

These six patients were treated with administration of oxygen, and two were placed in the left lateral decubitus position and symptoms rapidly resolved. Four patients experienced moderate to severe symptoms with chest pain, dyspnea, cough, perioral anesthesia, or a sensation of imminent death.

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In addition, one patient became unresponsive for five minutes. Signs included tachycardia, hypotension and cyanosis. These patients were treated with oxygen, and two were placed in the left lateral decubitus position. The patient who became unresponsive was also treated with Naloxone. Signs and symptoms completely resolved in all four patients.

In addition, one patient with Wegener’s granulomatosis and chronic dyspnea expired during the procedure from massive air embolism. Due to the patient’s chronic respiratory difficulties, the procedure was performed in a semi-sitting position. A large amount of air was visualized fluoroscopically in the heart, and after being turned into the left lateral decubitus position, the patient went into cardiac arrest.

The authors conclude that air embolism is uncommon, having occurred in only 15 patients out of 4,404 undergoing placement of a tunneled central venous catheter. Ten of these patients were asymptomatic or had only mild symptoms. All were treated with supplemental oxygen with complete resolution of signs and symptoms in all patients, except for one who died from massive air embolus.

Risk factors for air embolization include dehydration and performance of the procedure in sitting or semi-sitting positions, both of which decrease central venous pressures. Therefore, prevention of air embolism during central venous catheter placement includes:

  • having the patient well-hydrated;
  • placing the patient in a flat or head down position;
  • using a long sheath and positioning its tip in the upper inferior vena cava, which has a higher pressure than the superior vena cava;
  • not using a peel-away sheath, but instead using two stiff guide wires for catheter insertion.

Treatment of air embolus includes administration of oxygen, which is highly effective. Most patients have only mild symptoms or no symptoms at all. However, air embolus can cause severe symptoms and can be fatal. Prevention of air embolism by using a meticulous technique, in particular, not leaving the sheath or catheter open to air, is best.

If an air embolus should occur, administration of 100% oxygen is the most effective treatment. The study authors’ suggestion for redesigning the introducer sheath to include a hemostatic valve has turned out to be a promising one, with several manufacturers having produced a new sheath with a hemostatic valve while still maintaining the peel-away design since this study was first conducted.


Reference:
Vesely TM. Air Embolism during Insertion of Central Venous Catheters. Journal of Vascular and Interventional Radiology 2001; 12 (November): 1291-1295.

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