Recall of awareness during cardiac anaesthesia: influence of feedback information to the anaesthesiologist

We interviewed 303 cardiac surgery patients to evaluate the incidence of intraoperative awareness with recall.
First, we randomly interviewed 99 patients, of whom four patients (4%) reported awareness and recall. We informed the cardiac anaesthesiologists of the results of these interviews, and we also gave general information regarding means to reduce awareness and recall during general anaesthesia. Thereafter, we interviewed 204 consecutive cardiac surgery patients. Now, three of the patients (1.5%) had intraoperative awareness with recall. The reduction in the incidence from 4% to 1.5% was not significant. However, the doses of principal anaesthetic drugs had increased significantly between the two interview phases, while the dose of pancuronium, the main muscle relaxant used, had decreased significantly. Also, there was a significant increase in the number of anaesthesias where anaesthetic agents had been administered continuously instead of bolus or non-continuous dosing techniques. Between the patients with awareness and recall and those without it, there was no difference in the doses of anaesthetic agents given. The patients with awareness were significantly younger than those not aware.
In conclusion, with educational measures and vigilance over the problem, the incidence of intraoperative awareness during cardiac anaesthesia may be reduced. The incidence figure of 1.5% we observed is of the magnitude reported recently by others with modern cardiac anaesthesia techniques.