A surgeon’s assessment of inadequate neuromuscular antagonism in a case of prolonged neuromuscular blockade
An 82-year-old 74 kg woman presented for completion of a right extended hemicolectomy for colonic dysplasia. Her past medical history included long-standing hypertension, obesity, dyslipidemia, type 2 diabetes mellitus, and glaucoma. Her surgical history included bilateral eye procedures for glaucoma, left Achilles tendon repair, and a colonic resection for dysplasia 4 years ago. Outside hospital records describing her prior surgeries could not be obtained. She denied any anesthesia-related complications with her previous procedures, family history of anesthetic complications, or family history of neuromuscular disorders. Her medications at the time of surgery included aspirin, bimatoprost-timolol ophthalmic solution, calcium with vitamin D, dorzolamide ophthalmic solution, ezetimibe, glyburide, hydrochlorothiazide, insulin glargine, lisinopril, pravastatin, and prednisolone ophthalmic solution. The patient received 2 mg of intravenous midazolam pre-operatively, and induction was accomplished with 100 mcg of fentanyl, followed by 150 mg of propofol. Rocuronium 50 mg was then given to facilitate endotracheal intubation. The patient received 0.4 mg of hydromorphone shortly after induction as well as 3 g of ampicillin-sulbactam intravenously. Anesthesia was maintained throughout the case at 1MAC of end-tidal desflurane with 50/50 air and oxygen. Esophageal temperature was kept above 35°C throughout the case using active warming with a forced air warming device.\nOur involvement in the case begins at 1.5 h after induction, at which point an anesthesia personnel change occurred. It was noted that 10 mg of rocuronium was given 15 min prior to hand-off communication due to the surgeon’s request for additional relaxation. Monitoring of neuromuscular function was not performed at that time and the surgeon’s assessment was made by tactile feel in the surgical field. Shortly after hand-off, a nerve stimulator (TOF-Watch, Bluestar Enterprises, Omaha NE) was attached over the facial nerve using electrocardiogram pads and it was set to 60 mA, revealing a train-of-four (TOF) count of 0 at the corrugator supercilii. At 1.75 h after induction, TOF count was still 0 and the post-tetanic count (PTC) was 0. The post-tetanic count was determined by 5 sec of 50 Hz tetanic stimulation followed 3 sec later by 1 Hz single stimulation. An additional nerve stimulator was attached over the ulnar nerve giving the same results.\nSurgery was completed at approximately 2 h post-induction, and TOF count remained 0 with a PTC of 0. Desflurane was discontinued and an infusion of propofol 25-50 mcg/kg/min was started. A Mapleson F circuit was constructed and the patient was transferred to the post-anesthesia care unit (PACU) while delivering positive pressure ventilation using 100% oxygen. End-tidal desflurane was 0% prior to transportation. Consideration was made for a selective relaxant binding agent (SRBA) such as sugammadex, however, it is not currently available in the United States. On arrival to the PACU, she was hemodynamically stable with a skin temperature of 36.2°C. Laboratory studies were sent with results and reference values as shown in . The laboratory results were similar to pre-operative values except for serum potassium, which was 3.6 mmol/L pre-operatively. The patient received 40 mEq of intravenous potassium given at 10 mEq/h to correct the hypokalemia. Hepatic enzymes had been assessed within recent months and were found to be within normal limits.\nMechanical ventilation was initiated and propofol infusion was continued. TOF and PTC monitoring continued every 15 min. At 3.5 h after induction, TOF count was 0, PTC was 1, and no spontaneous respiratory effort was noted. At 4.5 h, TOF count was 1. At 5.5 h, TOF ratio was 90%. Since the TOF-Watch was not placed or calibrated at the beginning of surgery, and due to prolonged neuromuscular blockade, it was decided to give an acetylcholinesterase inhibitor prior to extubation. The patient was given 5 mg of neostigmine with 0.6 mg of glycopyrrolate and extubated without difficulty 10 min later. She demonstrated no signs of respiratory compromise and her recovery was otherwise uneventful.