[Critical incidents during regional anesthesia in Japanese Society of Anesthesiologists-Certified Training Hospitals: an analysis of responses to the annual survey conducted between 1999 and 2002 by the Japanese Society of Anesthesiologists].

Background: Recently, a national survey in France including 35,439 patients who had received spinal anesthesia showed that the incidences of cardiac arrest and mortality associated with spinal anesthesia were 2.5 and 0.8 per 10,000 anesthetics, respectively. In this study, we investigated these values using data obtained from annual surveys conducted by the Japanese Society of Anesthesiologist (JSA).

Methods: Since 1994, JSA has conducted annual surveys concerning critical incidents in the operating theater by sending confidential questionnaires to JSA-certified training hospitals, then collecting and analyzing the responses. We investigated critical incidents associated with regional anesthesia using data from annual surveys between 1999 and 2002. The questionnaire was identical in each survey conducted during these years. The total number of anesthetics available for this analysis was 3,855,384, of which spinal anesthesia, combined spinal-epidural anesthesia and epidural anesthesia were performed in 409,338, 146,282, and 69,001 patients, respectively. In patients receiving regional anesthesia, 628 critical incidents including 108 cardiac arrests, and 45 subsequent deaths were reported. The causes of critical incidents were classified as follows: totally attributable to anesthetic management, due mainly to intraoperative pathological events, preoperative complications, and surgical management. IP consists of coronary ischemia including coronary vasospasm not suspected preoperatively, arrhythmias including severe bradycardia, pulmonary thromboembolism, and other conditions. Mortality was determined by postoperative day 7. Statistical analysis was performed by chi-square test and Mann-Whitney test. A p value less than 0.05 was considered significant.

Results: The incidences of cardiac arrest and mortality due to all etiologies were 1.69 and 0.76 with spinal anesthesia, 1.78 and 0.68 with combined spinal-epidural anesthesia, and 1.88 and 0.58/10,000 anesthetics with epidural anesthesia, respectively. The incidences of cardiac arrest and mortality due to anesthetic management were 0.54 and 0.02 with spinal anesthesia, 0.55 and 0.00 with combined spinal-epidural anesthesia, and 0.72 and 0.14/10,000 anesthetics with epidural anesthesia, respectively. These values did not significantly differ among regional anesthesia. Death attributable to anesthetic management was reported in 2 patients: both patients were classified as ASA-PS 3 E, and developed cardiac arrest; one due to inadvertent high spinal anesthesia with spinal anesthesia, and the other due to local anesthetic intoxication with epidural anesthesia. Anesthetic management and intraoperative pathological events comprised 33 and 43% of cardiac arrests, respectively. The distribution of causes of death was as follows: anesthetic management, 5%; intraoperative pathological events, 34%; preoperative complications, 35%; surgical management, 26%. Among the causes of anesthetic management-induced critical incidents, inadvertent high spinal anesthesia was the leading cause of cardiac arrest in spinal and combined spinalepidural anesthesia: 90% of arrests occurred in patients with ASA-PS 1+2; 88% in patients below 65 years of age; 45 and 25% in patients undergoing hip or lower extremities surgery, and cesarean section, respectively. Among the causes of intraoperative pathological event-induced critical incidents, pulmonary thromboembolism was the leading cause of cardiac arrest in spinal and combined spinal-epidural anesthesia: 59% of arrests occurred in patients with ASA-PS 1+2; 81% in patients above 66 years of age; 91% in patients undergoing hip or lower extremity surgery.

Conclusions: The incidence of cardiac arrest and mortality associated with spinal anesthesia in Japan was shown to be in the same order as in France by analyzing a larger population. In patients with good ASA-PS, critical incidents occurred more often under regional anesthesia than under general anesthesia. Inadvertent high spinal anesthesia should be carefully avoided. We should also pay much attention to subclinical deep vein thrombosis in patients who were scheduled for hip or lower extremity surgery, and tourniquet- or bone cement-associated pulmonary embolism in these patients.