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Oral dantrolene causes a dose-dependent depression of skeletal muscle contractility. A 52-year-old man treated with oral dantrolene for spasticity after spinal cord injury was scheduled to undergo irrigation and drainage of a thigh abscess under general anesthesia. He had taken 50 mg oral dantrolene per day for 3 years. Under standard neuromuscular monitoring, anesthesia was performed with propofol, rocuronium, and sevoflurane. A bolus dose of ED95 (0.3 mg/kg) of rocuronium could not depress T1 up to 95%. An additional dose of rocuronium depressed T1 completely and decreased the train-of-four (TOF) count to zero. There was no apparent prolongation of the neuromuscular blocking action of rocuronium. The TOF ratio was recovered to more than 0.9 within 40 minutes after the last dose of rocuronium. A small dose of oral dantrolene does not prolong the duration of action and recovery of rocuronium.

Magnesium has been used frequently both as an anticonvulsant for preeclampsia and in the treatment of preterm labor. Magnesium also results in potentiation of the effects of neuromuscular blocking drugs, and attenuates their reversal with anticholinesterase [1]. Prolongation of the duration of the neuromuscular blockade (NMB) increases the risk of residual paralysis. Unlike anticholinesterase, sugammadex binds steroidal muscle relaxants by encapsulation, and it can rapidly and completely antagonize the action of the NMB. Theoretically, magnesium sulfate may reduce the efficacy of sugammadex [2]. We report a successful reversal of NMB with sugammadex in a patient with eclampsia who was treated with magnesium intraoperatively and showed incomplete reversal with anticholinesterase from rocuronium-induced NMB. A 30-year-old multipara (height 167 cm, weight 62 kg) at 27 weeks and 5 days of gestation visited the emergency room (ER) complaining of epigastric soreness, nausea, vomiting, and headache since the previous night. She had no specific medical history. Her blood pressure was 200/124 mmHg, heart rate 86 beats/min, and respiratory rate 24 breaths/min. According to a non-stress test, the fetal heart rate was 150 beats/min. After intravenous administration of hydralazine 5 mg, her blood pressure decreased to 140/100 mmHg. Forty minutes later, a seizure occurred. Diazepam 10 mg was immediately administered intravenously, and just an hour after the patient’s arrival at the ER, an emergency cesarean section was performed under general anesthesia.

In patients with severely compromised airways, a tracheostomy is usually performed under local anesthesia. Dexmedetomidine can be a better choice of sedative for such patients because it causes minimal respiratory depression. We report two cases of patients with severe stenosis of the airways who underwent sedation with dexmedetomidine during tracheostomy under local anesthesia. In the first case, recurrent laryngeal cancer caused laryngeal stenosis, and the narrowest laryngeal width was less than 3 mm. In the second case, the tracheostomy opening site was narrowed to a diameter of 3.4 mm in a patient with a history of total laryngectomy. For both patients, sedation was induced by dexmedetomidine infusion and the tracheostomy was performed successfully under local anesthesia without any events. Dexmedetomidine seems to be an effective and safe sedative for tracheostomies in patients with critical airways. The management and implications of sedation with dexmedetomidine in the patients with severe stenotic airways are discussed.