BIS does not predict dreams reported after anaesthesia

Abstract

Dreaming during anaesthesia seems to be a separate phenomenon, not in general related to insufficient anaesthesia as indicated by high BIS levels.

Propofol dose and incidence of dreaming during sedation

“…Our result contrasts with studies during general anaesthesia reporting that BIS values were not significantly different between dreamers and nondreamers [9][10][11]. This suggests that a certain depth of anaesthesia is required before dreaming can occur and could be explored further using a randomized trial design.…”

Effect of epidural dexmedetomidine on intraoperative awareness and post‐operative pain after one‐lung ventilation

“…It is apparent that there may be an incidence of intraoperative awareness that persists despite a low displayed BIS value and the best preventative efforts 27 . Dreaming during anaesthesia seems to be a separate phenomenon, not in general related to insufficient anaesthesia as indicated by BIS levels 28,29 . BIS does not consistently reflect anaesthetic depth for different anaesthetic drug combinations 30,31 and has not been studied extensively in the presence of concomitant medications especially in elderly patients.…”

Unresponsiveness ≠ Unconsciousness

“…This will result in both false negative and false positive errors – which cannot be overcome with more sophisticated signal processing techniques. The numerous reports of failed detection of consciousness with recall 94 , dreaming 11,95 and response on the isolated forearm technique (connected consciousness) 33,34,96 by currently-used depth of anesthesia monitors are eloquent witness to this problem. To detect consciousness reliably, the electroencephalographic index should directly correspond with the actual neurobiological process required for consciousness – i.e.…”