During the study period, 1,273,060 total anesthetic records were available for query. Only 10 cases were identified in which the “Intraoperative Recall” event flag was marked. Thus, the calculated incidence of AWR from this dataset, using this method of identification was only 0.00079%. Three of these cases were documented as sedation with monitored anesthesia care, and were excluded from further analysis. The number of general anesthesia cases queried was 647,009, giving a calculated incidence of 0.0011% of AWR under general anesthesia in our EAR. We briefly describe the 7 identified cases of AWR during general anesthesia in a condensed case series below. A summary of key characteristics is provided in Table 1.
Case 1 occurred in a 35-year-old male with American Society of Anesthesiologists (ASA) physical status (PS) II. This patient had a mass of 70 kg and body-mass index (BMI) of 21.6 kg/m2. The surgical case was an elective posterior spinal fusion and internal fixation of levels L5 and S1. The patient was premedicated with 50 mg of fentanyl and 2 mg of midazolam. General anesthesia was induced with 130 mg of propofol, and muscle paralysis initiated with 50 mg of rocuronium. Intermittent boluses of rocuronium were used to maintain paralysis. Maintenance of anesthesia was with sevoflurane, and the lowest concentration during the majority of the 3.5 hour-long case was 1.77%. However, the concentration decreased to 0.9 to 1.1% in the approximately 10 minutes prior to turning the patient supine. This volatile anesthetic was augmented with a remifentanil infusion at 0.1 to 0.2 mcg/kg/min, and this infusion was discontinued approximately 10 minutes prior to turning supine. A total of 200 mcg of fentanyl was given in divided doses after extubation, approximately 20 minutes after discontinuation of the remifentanil infusion. Mean arterial pressures (MAP) was maintained in the range 80 mmHg to 120 mmHg, but this required a phenylephrine infusion at rates up to 0.5 mcg/kg/min plus intermittent boluses of ephedrine. His heart was in sinus rhythm, rates ranging 45 to 80 beats per minute (bpm). Processed EEG monitoring was not used.While in the PACU, the patient recalled waking up while in the prone position. There was no further documentation describing specific recollections of the patient or any interventions during the postoperative period. There is no documentation of psychiatric follow up.
Case 2 occurred in a 72-year-old male, ASA-PS III, with mass of 126 kg BMI of 43.6 kg/m2, for elective endoscopic sinus surgery. He was premedicated with 50 mcg of fentanyl and 2 mg of midazolam. General anesthesia was induced with 200 mg of propofol and 100 mcg of fentanyl. Muscle paralysis was maintained with boluses of rocuronium. Maintenance of anesthesia was achieved with intermittent boluses of fentanyl and sevoflurane; the lowest end-tidal sevoflurane concentration was 1.45%. Vitals were remarkable for atrial fibrillation, with heart rates between 60 to 95 bpm and no hypotension. Processed EEG monitoring was not used. Case duration was 2.5 hours. While in the PACU, the patient report recalling intraoperative conversations. He was unable to quote what was being said but “definitely heard talking”. He did not endorse recalling pain or distress; though paralyzed, he did not try to speak or move. The patient declined any psychiatric follow up.
Case 3 occurred in a 61-year-old woman, with ASA-PS III, mass of 107 kg, and BMI of 36.7 kg/m2. She presented after a ground level fall that caused a distal tibia-fibula fracture. She was taken to the operating room for placement of a tibial intramedullary nail. She was premedicated with 2 mg of midazolam. General anesthesia was induced with 180 mg of propofol, and 100 mg of lidocaine was given. Muscle paralysis initiated with 190 mg of succinylcholine and 30 mg of rocuronium. Maintenance of anesthesia was achieved with sevoflurane, and end-tidal concentrations ranged from 0.3 to 1.3% during the case. The BIS monitor was applied, and the highest BIS index value recorded was 54.8. Case duration was two hours. Vital signs during the case were heart rates between 55 to 75 bpm and MAP ranging from 95 mmHg to 115 mmHg, with minimal support by intermittent phenylephrine and ephedrine. After extubation and while still in the operating room, the patient stated that she was awake during the entire procedure but, could not say anything because of the endotracheal tube. She described trying to wiggle her foot to get the surgeon's attention but was unable to move. She recalled feeling instrumentation including “the drill in my leg” and “a hammer on my knee” during the case. She was distressed having felt pain through the entire duration of the case. There is no documentation of psychiatric follow up.
Case 4 occurred in a 33-year-old female, with ASA-PS III, with mass of 124 kg, with BMI of 48.1 kg/m2. She presented for elective laparoscopic splenectomy, and received no premedication. Anesthesia was induced with 200 mg of propofol, 16 mcg of dexmedetomidine, and 20 mg of ketamine. Muscle paralysis initiated with 160 mg of succinylcholine and 90 mg of rocuronium with intermittent boluses of rocuronium throughout the case to maintain paralysis. The patient had a history of difficult airway management, but was uneventfully intubated with a Glidescope. Total intravenous anesthesia (TIVA) was maintained with three infusions: propofol ranging from 100 to 150 mcg/kg/min, with additional intermittent boluses; dexmedetomidine at 0.4 mcg/kg/hr; and ketamine at 0.2 mg/kg/hr. Processed EEG monitoring was utilized during the case, but not applied until 5 minutes after incision, which was about 30 minutes after induction. The BIS index ranged 65-75 in the first 30 minutes after application. At this time, a relief in hands-on providers occurred, and midazolam 2 mg was given. The highest recorded BIS index was 79.2, and this occurred during the middle portion of the case approximately 45 minutes after induction. The BIS index was > 65 for the majority of the surgical case. Vital signs were unremarkable with no support. Case duration was just over two hours. While in the PACU, the patient stated that she remembered the endotracheal tube in her throat, though that she was extubated shortly afterwards. The patient described no further awareness during the case and that she was not under stress from this memory. There is no documentation of psychiatric follow up.
Case 5 occurred in a 54-year-old female, with ASA-PS III, mass 67 kg, and BMI of 26.1 kg/m2. She presented for inguinal lymph node dissection. She was premedicated with midazolam 2 mg. Anesthesia was induced with 150 mg of propofol followed by rocuronium 30 mg to facilitate tracheal intubation. TIVA was maintained using a propofol infusion with a basal rate of 100 mcg/kg/min, with intermittent boluses, dexmedetomidine infusion at 0.2 mcg/kg/hour and ketamine infusion at 0.2 mg/kg/hour. The highest documented BIS index was 46.6. Vitals signs were remarkable only for mild bradycardia, with heart rates in the 50’s pre-induction. She was normotensive throughout the two hour case, with no support. In the PACU, she reported intraoperative pain and recalled “feeling the stitches” being placed. There is no documentation of psychiatric follow up.
Case 6 occurred in a 61-year-old-female, with ASA-PS II, mass 59 kg, and BMI of 27.5 kg/m2, who underwent an elective bilateral breast augmentation. Prior anesthesia complications included postoperative nausea and vomiting. She was premedicated with midazolam 2 mg. General anesthesia was induced with 50 mg of propofol and 50 mcg of fentanyl. Paralysis was maintained with intermittent boluses of rocuronium. Maintenance of anesthesia employed remifentanil at 0.2 to 0.6 mcg/kg/min and dexmedetomidine between 0.2 to 0.7 mcg/kg/hr. Approximately 20 minutes after surgical incision (and 40 minutes after induction) a propofol infusion at 50 mcg/kg/min was started, and the dose was subsequently increased to 75 mcg/kg/min for the last hour of the case. Vitals were unremarkable, with minimal intermittent doses of phenylephrine and ephedrine. The highest BIS index of 75.2 occurred near the start of surgery, about 15 minutes after induction. The patient was administered more fentanyl and propofol and that time, and the BIS index subsequently remained between 47 and 61 for the remainder of the two hour case. Other than selection of the “Intraoperative Awareness” flag, there is no further documentation of awareness or psychiatric follow up.
Case 7 occurred in a 29-year-old-female, with ASA-PS III, mass 98 kg, and BMI of 30.8 kg/m2. She presented for elective abdominal panniculectomy, bilateral brachioplasty, and bilateral mastopexy for redundant soft tissues after excess weight loss. Patient was premedicated with 2 mg of midazolam. General anesthesia was induced with 200 mg of propofol and 100 mg of lidocaine was given. Muscle paralysis was initiated with 10 mg of vecuronium and maintained with intermittent boluses. Maintenance of anesthesia was attempted with a TIVA approach utilizing infusions of propofol at 75 mcg/kg/min, dexmedetomidine at 0.6 mcg/kg/hour and intermittent boluses of midazolam (6 mg additional given). Vitals were notable for MAP ranges between 70 mmHg to 110 mmHg, sinus rhythm with heart rates 75 bpm to 100 bpm. Processed EEG monitoring was utilized during the case and notable BIS index ranging from 68 to 75 in the 25 minutes following incision. Despite additional intravenous (IV) medications including another 2 mg of midazolam, 150 mg of propofol bolus, and increased infusion dose of propofol to 125 mcg/kg/hour, the BIS index remained elevated above 70. An additional 10 mg dose of vecuronium was given and did not result in loss of TOF. It was then recognized that her IV access had been lost. The patient was started immediately on sevoflurane at 3.5%. A right internal jugular line was placed for definitive access. Additional midazolam was given and prior maintenance TIVA was continued. Notably, the BIS index ranged 30 to 40 for the remainder of the two-hour case. The awareness flag was selected by the anesthesiologist with concern for possible awareness. There is no further documentation of AWR or psychiatric follow up. The patient had another augmentation surgery the following year, and there was no mention of prior awareness documented in her pre-operative evaluation.