INCIDENCE OF AWARENESS IN TOTAL IV ANESTHESIA BASED ON PROPOFOL, ALFENTANIL AND NEUROMUSCULAR BLOCKADE

Background: There is no reliable technique for monitoring drug concent rations in total i.v. anaesthesia (TIVA) with muscle relaxation. An in creased risk of awareness with TIVA has been stated as a possible draw back (1, 2). The present study was conducted in order to assess the in cidence of conscious awareness in TIVA based on propofol, alfentanil a nd neuromuscular blockade. Methods: One thousand patients anaesthetize d with TIVA based on propofol, alfentanil, and neuromuscular blockade were subjected postoperatively to a structured interview for conscious awareness on two separate occasions: on discharge from the post-anaes thesia care unit, and the day after anaesthesia. Five hundred of those patients were also interviewed a third time, approximately 1 week lat er. Results: Two cases of awareness were detected (0.2%). One of these was identified immediately after extubation. The second patient had n o memory of intraoperative events or dreams at the first interview, re called a bad dream on the day after, and had explicit recall of intrao perative events at the interview 8 days later. in both cases, haemodyn amic signs of inadequate anaesthesia were present. The incidence of co nscious awareness in this study is similar to the lowest previously re ported incidence of awareness following general anaesthesia in patient s who had been paralyzed and thereafter subjected to a structured post anaesthesia interview. Conclusions: If the true incidence of conscious awareness is to be determined, interviews must be extended beyond the first postoperative day. Our study indicates that ii appropriate dosi ng of propofol and alfentanil are adhered to, and proper action is tak en in case of haemodynamic alterations suggestive of inadequate anaest hesia, the incidence of conscious awareness in noncardiac TIVA with ne uromuscular blockade is low.