Awareness during general anaesthesia: a review of 81 cases from the Anaesthetic Incident Monitoring Study

Abstract

SummaryBecause of recent studies suggesting that awareness is still a major issue in anaesthetic practice, we reviewed 8372 incidents reported to the Anaesthetic Incident Monitoring Study. There were 81 cases in which peri-operative recall was consistent with awareness. There were 50 cases of definite awareness and 31 cases with a high probability of awareness. In 13 of the 81 incidents, the patients appeared to receive adequate doses of anaesthetic drugs. Where the cause could be determined, awareness was mainly due to drug error resulting in inadvertent paralysis of an awake patient (n ¼ 32) and failure of delivery of volatile anaesthetic (n ¼ 16). Less common causes included prolonged attempts at intubation of the trachea (n ¼ 5), deliberate withdrawal of volatile anaesthetic (n ¼ 4) or muscle relaxant apnoea with inadequate administration of hypnotic (n ¼ 3). An objective central nervous system depth of anaesthesia monitor may have prevented 42 of these incidents and an improved drug administration system may have prevented 32. On the basis of these reports, we have developed guidelines that may have prevented the majority of these incidents.

Awareness

“…Obwohl die Awareness nur 1-2 aller Patientenklagen [21] oder Zwischenfälle [9] im Zusammenhang mit der Anästhe-sie ausmacht, dürfen die Auswirkungen nicht bagatellisiert werden [38]. …”

“…Eine Sonderform der Awareness ist die "wache Paralyse": Versehentlich wird einem wachen Patienten ein Muskelrelaxans verabreicht -Medikamentenverwechslungen kommen leider immer wieder vor und wirken sich bei Muskelrelaxanzien sehr dramatisch aus. So waren in einer Analyse von Anästhesiezwischen-fällen in Neuseeland 31 von 50 Fällen sicherer Awareness auf eine Medikamentenverwechslung zurückzuführen [9]. Die wache Paralyse wird ebenfalls mög-lich, wenn es am Ende der Anästhesie unterlassen wird, den Grad der Muskelrelaxation zu überprüfen, v. a. wenn bei Succinylcholin oder Mivacurium ein verzö-gerter Abbau vorliegt [50].…”

Fatores de risco para o despertar intraoperatório

“…Reported awareness cases with techniques using inhalation anesthesia in general seem to be associated with issues in the vaporizers or lack of anesthetic gas monitoring; Bergman et al 36 have reported in their study that in the 13% of the patients who experienced awareness there had been a failure in the supply of nitrous oxide or volatile agents as a malfunctioning of the equipment, showing that in most cases the anesthetic agent concentrations (exhaled and inhaled) had not been monitored.…”

“…The most frequent causes of motor paralysis complaints in awaken patients are errors made in the administration or identification of intravenous drugs. Among of which succinylcholine is the most frequently related with the wrongful administration in place of the sedative or hypnotic agents in the anesthetic induction 36 .…”

The Clinical Effectiveness of the Bispectral Index (BIS) To Reduce the Risk of Awareness for Elective Surgical Patients Undergoing General Anesthesia: A Prospective, Randomized, Double-Blind, Controlled Trial

“…There were 13 cases (16%) with no apparent cause. In 36 cases (44.5%), incidents were due to a low volatile inspired concentration or insufficient hypnosis, and in 32 cases (39.5%), the event was due to the drug's fault [26]. …”