Intraoperative awareness and recall during total hip arthroplasty.

A case of intraoperative recall and awareness in a patient with sickle cell disease who had received midazolam, 10 mg at induction of anesthesia, is reported. The patient was on opioids which may also have caused tolerance. Although the use of midazolam may have been judged to provide adequate amnesia, this was clearly not the case. Upon analysis of the reasons for recall, we predicted from a two-compartment model that the estimated blood level was 88 ng/mL-1; this level would have provided no amnesia. This case illustrates that recall can occur with the use of midazolam, especially if levels become subtherapeutic, and other measures should be taken to provide adequate anesthesia and amnesia.