WAKEFUL RESPONSE TO COMMAND INDICATES MEMORY POTENTIAL DURING EMERGENCE FROM GENERAL-ANESTHESIA

Objective. An important aspect of assessing anesthetic depth is determ ining whether a patient will remember events during surgery. We looked for a clinical sign that would indicate a patient's potential for mem ory formation during emergence from anesthesia. A clinical sign indica ting memory potential could be a useful endpoint for measuring the per formance of anesthetic depth monitors and for titrating administration of anesthetic agents. Methods. We evaluated patients' responses to co mmands to open the eyes, squeeze the hand four times, and count 20 num bers. These responses were correlated with results on recall, cued rec all, and multiple-choice memory tests. Main Results. Patients did not have evidence of memory formation until they sustained wakefulness suf ficiently long to complete at least four hand squeezes or count four n umbers. Of 28 patients, 13 (46%) with this sustained wakeful response had memory. Of 22 patients, 0 (0%) had evidence of memory formation wh en they demonstrated a brief wakeful response, defined as being respon sive to command but unable to complete more than one hand squeeze or c ount, or an intermediate response, defined as two or three hand squeez es or counts. Conclusions. We conclude that a brief wakeful response t o command indicates that a patient is unlikely to form memories, while a sustained wakeful response indicates that a patient may form memori es. Thus, a patient's wakeful response to command could be a useful in dicator of potential for memory.