Intraoperative Awareness During General Anesthesia

Objective: To investigate the incidence of intraoperative awareness during general anesthesia and to find the potential causes and to analyze the risk factors.Methods: 1000 noncardiac surgical patients who had undergone general anesthesia were structurally interviewed. Interviews were conducted in 1-3 days postoperatively for nonneurosurgery patients and 3-6 days postoperatively for neurosurgery patients.Results: Of all the inpatients, 16 (1.6%) patients were reported awareness and 6 (0.6%) were reported dreaming during general anesthesia. Seven of the 16 patients (43.75%) with awareness during operation had auditory perceptions, 8 (50%) were unable to move and 2 (12.5%) were unable to breathe, 14 (87.5%) had the sensations of operations on themselves, 11 (68.75%) felt pain, 6 (37.5%) had the sensations of endotracheal tube or felt tube in throat, and 1 (6.25%) felt fear during operation. Postoperative effects appeared in 4 of the 16 patients (25%). Awareness occurred in some of the patients undergone elective operation, but the ratio in the patients undergone laparoscopic surgery in gynecology is higher than others. Logistic regession analysis showed that awareness in gynecological patients undergone laparoscopic surgery was associated with the mean maintenance dose of propofol less than 4 mg·kg^-1·h^-1 (OR=20.426, 95%CI=1.634-374.152). Age, weight, anesthesia time, waiting time (from tracheal intubation to operation starting), ASA physical status, premedication of benzodiazepines, using of volatile anesthetics, using of other hypnotic drugs, intraoperative hypotension and anesthesiologist did not influence the incidence of intraoperative awareness.Conclusion: The incidence of awareness in noncardiac surgery patients during general anesthesia was 1.6% and dreaming during anesthesia was described by 0.6% of the patients in our study. The incidence of awareness is higher in gynecological patients undergone laparoscopic surgery than others. While its mean maintenance dose of propofol is less than 4 mg·kg^-1·h^-1 is a risk factor of intraoperative awareness.