General Anesthesia Linked To Pulmonary Risk In Carotid Endarterectomy

By Jeff Evans

WASHINGTON -- Carotid endarterectomies that are performed on patients under general anesthesia may be associated with a significantly greater risk of pulmonary complications than when such procedures are carried out on pateints under regional anesthesia, Dr. Byron J. Faler reported at the annual meeting of the Eastern Vascular Society.

"Currently there are conflicting results in the literature as to whether regional anesthesia reduces postoperative complications, compared to general anesthesia for carotid endarterectomy," said Dr. Faler of the department of surgery at the Washington DC VA Medical Center.

Regional anesthesia has been presumed to be advantageous over general anesthesia because of less hemodynamic instability, the ability to perform intraoperative clinical neurologic monitoring, as well as the avoidance of the effects and potential complications that endotracheal intubation and mechanical ventilation have on the patient.

"It is not clear whether these effects translate into true clinical benefits, such as decreased postoperative complications," he said.

To determine if regional anesthesia reduced the incidence of major complications and death, compared with general anesthesia, Dr. Faler and his colleagues used data from 123 Veterans Affairs medical centers in the VA National Surgical Quality Improvement Program.

In the analysis that was done of all carotid endarterectomies that were performed at the centers during the period 1995-2003, significantly higher percentages of the 18,466 patients who received general anesthesia had a previous stroke (19.3% vs. 16.5%) compared with those who had regional anesthesia. In addition, a significantly higher percentage of these patients with general anesthesia also had a previous transient ischemic attack (33.2% vs. 30.8%), and a rating of 4 on the American Society of Anesthesiologists' system of classifying physical status (15.4% vs. 11.9%), compared with those 2,687 patients who received regional anesthesia.

Pulmonary complications, which included pneumonia, any unplanned intubation, and failure to wean from the ventilator after 48 hours, occurred at a significantly higher rate in patients who underwent general (1.67%) rather than regional (0.71%) anesthesia.

The incidence of preoperative chronic obstructive pulmonary disease (COPD) did not differ significantly between the general (16%) and regional anesthesia (17.2%) groups.

In multivariate analyses, patients who received general anesthesia were nearly four times more likely to develop pulmonary complications if they had COPD (odds ratio 5.7) than if they did not have it (odds ratio 1.6).

"Patients should be properly screened for pulmonary risk factors, especially COPD," and those with such risk factors "should be considered for a [carotid endarterectomy] under regional anesthesia," Dr. Faler suggested.

In patients without COPD, significant independent risk factors for pulmonary complications besides general anesthesia included type 1 or 2 diabetes, and a glomerular filtration rate of less than 30 mL/min per 1.73 m2 of body surface area. In addition, an ASA physical status of 4, current smoking, the need for assistance in activities of daily living, and a history of stroke or transient ischemic attack were also seen as independent risk factors in patients without COPD.

Only age and a glomerular filtration rate of 30-59 mL/min per 1.73 m2 were significant independent risk factors for pulmonary complications in patients with COPD.

The rates of cardiac (myocardial infarction or cardiac arrest) and neurologic (entry into coma or a new neurologic deficit lasting more than 24 hours) complications, as well as 30-day mortality, were not found to differ significantly between the groups.