[Annual study of perioperative mortality and morbidity for the year of 1999 in Japan: the outlines--report of the Japan Society of Anesthesiologists Committee on Operating Room Safety]

Abstract

Anesthetic mortality and morbidity in Japan Society of Anesthesiologists (JSA) Certified Training Hospitals (CTH) for the year 1999 were reported as continuation of annual studies started in 1993. The JSA Committee on Operating Room Safety (CORS) sent confidential questionnaires to 774 CTH and received valid responses from 60.3% of hospitals. A total number of 793,840 anesthetics were documented. The respondents were asked to report all cases of cardiac arrests and other critical incidents (serious hypotension, serious hypoxemia and others), and their outcomes (death in operating room, death within 7 days, transfer to vegetative state and rescue without sequelae) as well as one principal cause for each incident from list of 52 items. They were also requested to submit the tabulation of patients by ASA physical status, age distribution, surgery sites and anesthetic methods. Analysis was made by total incidents under anesthesia/surgery, and also by incidents totally attributable to anesthetic management (AM), due to preoperative complications (PC), due to intraoperative pathological events (IP) and due to surgery (SG), with special reference to each of four tabulation groups and the whole group of patients. This paper focused analysis on all patients, as analyses with special reference to ASA physical status, age distribution, surgery sites and anesthetic methods were previously reported. Total incidence of cardiac arrest under anesthesia/surgery was 6.53 per 10,000 anesthetics. PC, IP and SG represented principal causes in 42.9%, 22.0% and 21.4% causes of total cardiac arrest cases, respectively. AM was noted as the principal cause in 12.0% of cases, with an incidence rate of 0.78 per 10,000. In 52 more detailed classification of principal causes, the most frequent cause of cardiac arrest was preoperative hemorrhagic shock, 20.3% of all cardiac arrests. The second cause was massive hemorrhage and/or hypovolemia due to surgical procedures (13.1%), and the third was intraoperative myocardial infarction/coronary ischemia/coronary spasm (9.5%). Prognoses of cardiac arrest cases declined due to PC: 71.1% of cardiac arrests died in the operating room or within 7 days after surgery and only 19.8% survived without sequelae. The best prognoses were found in cardiac arrest cases due to AM: 69.4% survived without sequelae and 12.9% died. The mortality rate post-cardiac arrest was 3.44 per 10,000 anesthetics, of those 0.10 due to AM, 0.57 due to IP, 1.99 due to PC and 0.76 due to SG. The mortality rate after critical incidents other than cardiac arrest such as severe hypotension and severe hypoxemia was 3.75, of those 0.03 due to AM, 0.28 due to IP, 2.31 due to PC and 1.13 due to SG. The final mortality rate attributable to anesthesia/surgery including deaths post-cardiac arrest and after other critical incidents was 7.19 per 10,000 anesthetics and very close to 7.18 [6.22, 8.13], that of mean [95% C.I.] in 1994-1998. The final mortality rate totally attributable to anesthesia was 0.13 per 10,000 anesthetics, which was significantly improved from 0.21 [0.15, 0.27], that of mean [95% C.I.] in 1994-1998. IP, PC and SG showed the final mortality rate of 0.84, 4.30 and 1.89, respectively. Five major causes of all critical incidents were massive hemorrhage due to surgical procedures (20.8%), preoperative hemorrhagic shock (10.7%), surgical technique (8.0%), inappropriate airway management (5.2%) and intraoperative myocardial infarction and coronary ischemia (4.5%). Drug overdose or selection error (3.9%) and overdose of main anesthetic (2.9%) as a result of human error occupied the 7th and 10th places. As far as anesthetic management to reduce mortality and morbidity related to anesthesia is concerned, we should increase vigilance to avoid human errors in addition to improving preanesthetic preparations and assessment of cardiovascular status as well as intraoperative management of cardiovascular events.