The Thai Anesthesia Incidents Study (THAI study) of ambulatory anesthesia: II. Anesthetic profiles and adverse events.

BACKGROUND: There is a continuing trend to have more elective surgery performed on an outpatient basis. OBJECTIVE: To determine anesthetic profiles and adverse events in practice of ambulatory anesthesia for elective surgery in different levels of hospitals across Thailand. MATERIAL AND METHOD: A prospective descriptive study was conducted in 20 hospitals comprising seven university, five regional four general and four district hospitals across Thailand. Consecutive patients undergoing anesthesia for elective surgery were included. The included patients, classified as outpatients, were selected and extracted for summary of the result by using descriptive statistics. RESULTS: The authors reported 7786 outpatients receiving anesthesia for elective surgery. The majority of patients were in ASA class 1 and 2 (96.2%) while the rest were in ASA class 3 (3.8%). Nearly 90% of the ASA class 3 patients were in university hospitals. The majority of patients (83.1%) did not receive premedication. Diazepam was used more frequently (11.5% vs. 0.1%) than other drugs. Noninvasive blood pressure monitoring and pulse oximetry were used in greater than 90%, while electrocardiogram (EKG) was used in 67.2% and end tidal CO2 in only 6.8%. The three most common anesthetic techniques were general anesthesia (including inhalation anesthetics), total intravenous anesthesia (TIVA), and monitored anesthesia care (MAC). Regional anesthesia was performed in 12% of cases. The three most common regional anesthetic techniques were brachial plexus block (7.1%), spinal anesthesia (2.21%), and other peripheral nerve blocks (2.06%). Propofol was the most common drug for induction. Succinylcholine was used for intubation in 8.8%. The three most common nondepolaring neuromuscular blocking agents were atracurium, cisatracurium, and vecuronium. Fentanyl was the most common drug used among opioids. The three most common volatile anesthetics were sevoflurane, halothane, and isolurane. Lidocaine was the most frequently used in 29.76% of cases, while bupivacaine in 7.9% and ropivacaine only in 0.05%. The majority of the events relating to respiratory system were hypoxia or oxygen desaturation (18:10,000), reintubation (2.6:10,000) and difficult intubation (2.6:10,000), pulmonary aspiration (2.6:10,000), and esophageal intubation (1.3:10,000). Other adverse events included awareness (1.3:10,000), suspected myocardial infarction or ischemia (1.3:10,000), and drug error (1.3:10,000). Five patients (0.06%) received unplanned hospital admission. No patients developed cardiac arrest or died. CONCLUSION: The incidence of major adverse events was low in ambulatory anesthesia for elective surgery when compared to the incidence in general surgical population. The majority of the events occurred in the respiratory system. The authors did not find any complications relating to regional anesthesia. Despite a low incidence of adverse events in ambulatory anesthesia, anesthesia personnel who are responsible for ambulatory anesthesia should have adequate knowledge and skills in selection and preparation of the patients. Therefore, a system of preanesthesia evaluation is very important.