Less Invasive Anesthesia Safer in Endovascular AAA Repair
Epidurals didn't seem to be any better than general anesthesia on any count, but none of the less-invasive anesthesia methods hurt mortality rates, the group reported in the November issue of the Journal of Vascular Surgery.Use of local anesthesia, with or without monitored anesthesia care, or spinal anesthesia should increase for suitable patients, Edwards' group argued.Endovascular techniques were originally introduced to reduce the risk of open surgical repair for the "relatively high-risk population inherent with aneurysmal disease of the aorta," they noted.
To determine what the results have been when anesthesia further capitalizes on the less-invasive nature of the endovascular intervention, Edwards' group analyzed the American College of Surgeons' National Surgical Quality Improvement Program database.It included reporting from 211 North American hospitals during the study period from 2005 through 2008.Of the 6,009 elective procedures identified for endovascular repair of infrarenal abdominal aortic aneurysms, most (81%) were done under general anesthesia.Another 419 cases (7%) were done with spinal anesthesia, 331 (5.5%) with an epidural, and 391 (6.5%) with local anesthesia.Monitored anesthesia care was lumped in with local anesthesia, since some form of local anesthesia is required even with centrally acting sedative and dissociative agents.
The risk of any morbidity tended to be higher among general anesthesia patients than for those who received spinal anesthesia (odds ratio 1.4, P=0.0831) or local anesthesia (OR 1.6, P=0.0181).But multivariate adjustment for age, gender, surgical fitness, and other factors eliminated the associations.Risks of dying or suffering renal or wound complications were similar across groups in both univariate and multivariate analyses.
On the other hand, persistent increased risk was seen with general anesthesia for pulmonary morbidity, such as pneumonia or failure to wean from the ventilator within two days.This risk was four-fold higher compared with spinal anesthesia and 2.6-fold higher compared with local anesthesia after multivariate adjustment (P=0.020 and P=0.041, respectively).Length of hospital stay was 10% longer for general anesthesia compared with spinal anesthesia and 20% longer compared with local anesthesia in the adjusted analysis (P=0.0001 and P<0.0001, respectively).The mean duration of stay was 2.9 ± 4.2 days with general anesthesia compared with 2.1 ± 1.8 with spinal anesthesia and 2.3 ± 6.1 with local anesthesia.
"Given the high estimated cost of such nosocomial pneumonias (more than $12,000 per occurrence) and the potential savings of the observed decreases in length of stay, the significance of these data to contemporary American health care is obvious," Edwards' group concluded.The reason results weren't better with epidurals might have been because of the local anesthetic or adjuvant agents typically used with them, they suggested.
"When patients are supine, cephalad spread of local anesthetics or epidural narcotics to the midthoracic or lower cervical regions during a continued infusion may impair pulmonary mechanics, thus increasing the risk of postoperative pulmonary dysfunction and length of stay," the group explained in the paper.
In addition, the narcotics that are often added, "also have the potential to centrally suppress respiratory drive and thereby affect rates of reintubation and length of stay," they noted.Avoiding general anesthesia with spinal or local anesthesia, though, may be beneficial because it avoids the impact of endotracheal intubation and mechanical ventilation, along with possible residual neuromuscular paralysis afterward, they pointed out.The group cautioned that the study was limited by lack of data on conversion between anesthesia techniques and why a particular type of anesthesia was chosen for a given patient.The observational results were likely influenced by surgeon and anesthesiologist preferences, medical risk, anatomy, and many other confounding factors, they added.