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Chapter: Clinical Anesthesiology: Perioperative & Critical Care Medicine: Anesthetic Complications

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Anesthetic Complications: Awareness

continuing series of media reports have imprinted the fear of awareness under general anesthesia into the psyche of the general population.

AWARENESS

 

continuing series of media reports have imprinted the fear of awareness under general anesthesia into the psyche of the general population. Accounts of recall and helplessness while paralyzed have made unconsciousness a primary concern of patients undergoing general anesthesia. When unintended intraoperative awareness does occur, patients may exhibit symptoms ranging from mild anxiety to posttraumatic stress disorder (eg, sleep disturbances, nightmares, and social difficulties).

Although the incidence is difficult to measure, approximately 2% of the closed claims in the ASA Closed Claims Project database relate to awareness under anesthesia. Analysis of the NHS Litigation Authority database from 1995–2007 revealed that 19 of 93 relevant claims were for “awake paralysis.” Clearly, awareness is of great concern to patients and may lead to litigation. Certain types of surgeries are most frequently associated with awareness, includ-ing those for major trauma, obstetrics, and major cardiac procedures. In some instances, awareness may result from the reduced depth of anesthesia that can be tolerated by the patient. In early studies, recall rates for intraoperative events during major trauma surgery have been reported to be as frequent as 43%; the incidence of awareness during cardiac surgery and cesarean sections is 1.5% and 0.4%, respectively. As of 1999, the ASA Closed Claims Project reported 79 awareness claims; approximately 20% of the claims were for awake paralysis, and the remainder of the claims were for recall under general anesthe-sia. Most claims for awake paralysis were thought to be due to errors in drug labeling and administra-tion, such as administering paralytics before induc-ing narcosis. Since the 1999 review, another 71 cases have appeared in the database. Claims for recall were more likely in women undergoing general anesthesia without a volatile agent. Patients with long term sub-stance abuse may have increased anesthesia require-ments which if not met can lead to awareness.

 

Other specific causes of awareness include inad-equate inhalational anesthetic delivery (eg, from vaporizer malfunction) and medication errors. Some patients may complain of awareness, when, in fact, they received regional anesthesia or monitored anes-thesia care; thus, anesthetists should make sure that patients have reasonable expectations when regional or local techniques are employed. Likewise, patients requesting regional or local anesthesia because they want to “see it all” and/ or “stay in control” often can become irate when sedation dulls their memory of the perioperative experience. In all cases, frank dis-cussion between anesthesia staff and the patient is necessary to avoid unrealistic expectations.

 

Some clinicians routinely discuss the possibil-ity of intraoperative recall and the steps that will be taken to minimize it as part of the informed consent for general anesthesia. This makes particular sense for those procedures in which recall is more likely. It is advisable to also remind patients who are under-going monitored anesthesia care with sedation that awareness is expected. Volatile anesthetics should be administered at a level consistent with amne-sia. If this is not possible, benzodiazepines (and/or scopolamine) can be used. Movement of a patient may indicate inadequate anesthetic depth. Docu-mentation should include end-tidal concentrations of anesthetic gases (when available) and dosages of amnesic drugs. Use of a bispectral index scale (BIS) monitor or similar monitors may be helpful although randomized clinical trials have failed to demonstrate a reduced incidence of awareness with use of BIS when compared with a group receiving appropriate concentrations of volatile agents. Finally, if there is evidence of intraoperative awareness during post-operative rounds, the practitioner should obtain a detailed account of the experience, answer patient questions, be very empathetic, and refer the patient for psychological counseling if appropriate.

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