Intraoperative Recall

Incidence in USA: 20 million anesthetics annually

Incidence is approximately 0.1% in general surgical population and increases to approximately 1% in high-risk populations.

Procedure risk factors include OB surgery, cardiac surgery, trauma, and rigid bronchoscopy.

Pt risk factors include prior awareness, significant CV disease, COPD, substance abuse, chronic opioid use, and chronic benzodiazepine use.

Anesthetic risk factors include absent/low benzodiazepine premedication, absent/low halogenated agent, and dense NM blockade.

PTSD is a common sequela (up to 50% incidence).

Awareness caused a significant fraction of closed claims against anesthesia personnel (1.9–12%).

Many cases are preventable and identified as attributable to lapses in technique.

Explicit recall: Conscious, articulable recollection of events when intended to be unaware.

Implicit recall: Change in behavior attributable to perception of intraoperative events, but no explicit awareness. Much harder to study.

Intraoperative awareness: Consciousness during presumed general anesthesia; does not necessarily lead to postoperative recall.

Hemodynamic changes are neither sensitive nor specific signs of awareness.

Processed EEG monitoring (such as BIS) may decrease incidence of awareness.

Maintenance of adequate end-tidal halogenated agent (≥0.7 MAC, age adjusted) using audible alarms may decrease incidence of awareness.