Cardiac arrest during neuraxial anesthesia: frequency and predisposing factors associated with survival.

The frequency and predisposing factors associated with cardiac arrest during neuraxial anesthesia remain undefined, and the survival outcome data are contradictory. In this retrospective study, we evaluated the frequency of cardiac arrest, as well as the association of preexisting medical conditions and periarrest events with survival after cardiac arrest during neuraxial anesthesia between 1983 and 2002. To assess whether survival after cardiac arrest differs for patients who arrest during neuraxial versus general anesthesia, data were also obtained for patients who experienced cardiac arrest under general anesthesia during similar surgical procedures during the same time interval. Over the 20-yr study period at the Mayo Clinic, there were 26 cardiac arrests during neuraxial blockade and 29 during general anesthesia. The overall frequency of cardiac arrest during neuraxial anesthesia for 1988 to 2002 was 1.8 per 10,000 patients, with more arrests in patients receiving spinal versus epidural anesthesia (2.9 versus 0.9 per 10,000; P = 0.041). In 14 (54%) of the 26 patients who arrested during a neuraxial technique, the anesthetic contributed directly to the arrest (high sympathectomy or respiratory depression after sedative administration), whereas in 12 (46%) patients, the arrest was associated with a specific surgical event (cementing of joint components, spermatic cord manipulation, reaming of the femur, and rupture of amniotic membranes). Patients who arrested during general anesthesia had a higher ASA classification than those who arrested during a neuraxial block (P = 0.031). Hospital survival was significantly improved for patients who arrested during neuraxial anesthesia versus general anesthesia (65% vs 31%; P = 0.013). The association of improved survival with neuraxial anesthesia remained statistically significant after adjusting for all patient/procedural characteristics, with the exception of ASA classification and emergency procedures. We conclude that a cardiac arrest during neuraxial anesthesia is associated with an equal or better likelihood of survival than a cardiac arrest during general anesthesia.