AWARENESS DURING ANESTHESIA

Abstract

The problem of intraoperative awareness has plagued anesthesiologists since the dawn of the modern era of anesthesia in the mid 1800s. In fact, early demonstrations of the administration of anesthesia were often ridiculed because patients experienced pain. There are several reports of awareness during anesthesia during the time period between the late 1840s and the mid-1940s. These reports were anecdotal, and there were certainly no scientific studies of intraoperative awareness from that era. The primary interest of the physician in those years was avoiding unpleasant patient recall. In addition to the patient experiencing pain and discomfort, the incident also reflected poorly upon the physician and could damage his or her reputation in the community. The introduction of muscle relaxants into the practice of anesthesia in the 1940s may have contributed to an increased incidence of intraoperative awareness. The routine use of muscle relaxants eliminated patient movement as a sign of light anesthesia and also introduced the problem of a patient being paralyzed while awake. The modern era of thought concerning awareness during anesthesia can be dated to studies conducted by Cheek in the late 1950s and 1960s.12, 13 These studies demonstrated virtually no incidence of conscious recall after surgery. Under hypnosis, however, patients exhibited considerable recall of intraoperative events. Also of interest, Cheek discovered that patients with poor postoperative recovery recalled (under hypnosis) negative remarks made about them by members of the surgical team. Cheek's findings were dramatically underscored by Levinson's study of patients receiving general anesthesia that were subjected to a contrived intraoperative crisis.32 Although none of the 10 patients had conscious recall of the intraoperative crisis, hypnosis revealed accurate recall in 4 of the patients and considerable emotional agitation in another 4 patients. Levinson concluded that patients might be susceptible to recall of untoward intraoperative events, even while receiving general anesthesia. He also suggested that positive audio suggestions might favorably influence the patient's postoperative course and enhance recovery. Consequently, Levinson introduced the broader concept of learning during general anesthesia. At the same time the technique of learning during physiologic sleep had gained considerable popularity with the public. Unfortunately, studies that have attempted to evaluate the ability to “teach” the patient during anesthesia have produced inconsistent and contradictory results.