[Critical events in the operating room among 1,440,776 patients with ASA PS 1 for elective surgery]

The Japanese Society of Anesthesiologists (JSA) survey of critical incidents in the operating room has shown that preoperative complications are the leading causes of critical incidents, and affect the occurrence, severity and outcome of critical incidents which are due to causes other than preoperative complications. Causes of critical events in the operating room were examind in patients for elective surgery with American Society of Anesthesiologists physical status (ASA PS) 1.

JSA has conducted annual surveys of critical incidents in the operating room by sending and collecting confidential questionnaires to all JSA Certified Training Hospitals. From 1999 to 2002, 3,855,384 anesthesia patients were registered. Among these, 1,440,776 patients with ASA PS 1 for elective surgery were analyzed. The causes of critical incidents were classified as follows: totally attributable to anesthetic management (AM), mainly to intraoperative pathological events (IP), to preoperative complications (PC), and to surgical management (SM). IP consists of coronary ischemia mainly due to coronary vasospasm, arrhythmias, pulmonary embolism, and other conditions.

The incidences of cardiac arrest, critical incidents other than cardiac arrest and subsequent death were 9.86, 59.41 and 3.12 per 100,000 anesthesia cases, respectively. IP and SM were responsible for 36.6% and 34.5% of cardiac arrest, respectively. AM and SM were responsible for 46.7% and 26.8% of critical incidents other than cardiac arrest, respectively. SM, IP and AM were responsible for 66.7%, 22.2% and 4.4% of subsequent deaths (within 7 postoperative days), respectively. Coronary ischemia and pulmonary embolism were the main causes of death due to IP. The incidences of cardiac arrest and death totally attributable to AM were 1.87 and 0.14 per 100,000 anesthesia cases, respectively. Medication problems were responsible for 48.1% of arrests, while airway/ventilation problems were for 57.2% of critical incidents other than arrest. Human factors (SM combined with AM) were responsible for 53.5%, 73.5%, and 71.1% of cardiac arrest, critical incidents other than arrest and death, respectively.

Even in elective patients with good physical status, non-lethal incidents were not rare, and lethal incidents were also reported. We should pay significant attention to the following findings, and take some measures to overcome these problems especially related to human factors. Firstly, SM badly harmed some operative patients. Secondly, coronary vasospasm and pulmonary embolism were the main causes of death due to IP. Thirdly, drug administration and airway/ventilation management were the major causes of critical incidents totally attributable to AM. Human factors were responsible for 70.6% of critical incidents and 71.1% of deaths.