Cardiac arrest after spinal anesthesia in Thailand: a prospective multicenter registry of 40,271 anesthetics.

Background And Objectives: As part of the Thai Anesthesia Incidents Study of anesthetic adverse outcomes, we evaluated the incidence and factors related to cardiac arrest during spinal anesthesia.

Methods: During a 12-mo period (March 1, 2003, to February 28, 2004), a prospective, multicenter registry of patients receiving anesthesia was initiated in 20 hospitals (7 university, 5 tertiary, 4 general, and 4 district hospitals) across Thailand. Anesthesia personnel reported patient-, surgery-, and anesthetic-related variables and adverse outcomes, including cardiac arrest during spinal anesthesia (defined as the time period from induction of spinal anesthesia until the end of operation). Adverse event specific forms were recorded within 24 h of an anesthetic procedure whenever a specific adverse event occurred. Univariate and multivariate analysis were used to identify factors related to cardiac arrest during spinal anesthesia. A P value <0.05 was considered significant.

Results: In the registry of 40,271 cases of spinal anesthesia, there were 11 cardiac arrests, corresponding to an incidence of 2.73 (95% CI: 1.12-4.34) per 10,000 anesthetics. The mortality rate was 90.9% among patients who arrested. Among 11 patients who arrested, there were 5 cases of cesarean delivery and 6 cases of extremity surgery, including hip surgery. In 4 patients (36.3%), the anesthetic contributed directly to the arrest (high sympathetectomy, local anesthetic overdose, or lack of electrocardiography monitoring), whereas some arrests were associated with specific events (cementing of prosthesis, massive bleeding, suspected pulmonary embolism, and suspected myocardial infarction). From multivariate analysis, the risks of cardiac arrest during anesthesia were shorter stature (odds ratio 0.944 [95% CI: 0.938-0.951], P < 0.001), longer duration of surgery (odds ratio 1.003 [95% CI: 1.001-1.005], P = 0.002), and spinal anesthesia administered by the surgeon (odd ratio 23.508 [95% CI: 6.112-90.415], P < 0.001), respectively.

Conclusion: The incidence of cardiac arrest during spinal anesthesia was infrequent, but was associated with a high mortality rate. If the surgeon performed the spinal anesthetic, this was a significant factor associated with cardiac arrest. Increasing the number of anesthesiologists, improving monitoring guidelines for spinal anesthesia and improving the nurse-anesthetist training program may decrease the frequency of arrest and/or improve patient outcome.