Recurarization in the recovery room following the use of magnesium sulphate

A 67-yr-old man weighing 104 kg, with a history of hypertension, underwent laparoscopic cholecystectomy. His preoperative serum potassium was 3.4 mmol litre(-1). The patient received cisatracurium 14 mg, which was antagonized with neostigmine 2.5 mg and glycoprolate 0.5 mg at the end of the procedure. A repeat dose of neostigmine 2.5 mg and glycoprolate 0.5 mg was required 5 min later, as the neuromuscular block was incompletely antagonized. He was transferred to the recovery room about 10 min after the end of surgery, having had recovery of neuromuscular function demonstrated with no fade on peripheral nerve stimulation at 50 Hz for 5 s. Five minutes later he developed rapid atrial fibrillation, which was treated over 5 min with magnesium sulphate 2 G i.v. Within the next 3 min, the patient developed marked neuromuscular weakness of a non-depolarizing pattern leading to respiratory arrest. This necessitated re-intubation of the trachea and artificial ventilation for 20 min, until there was spontaneous recovery of neuromuscular function demonstrated by peripheral nerve stimulation. Administration of magnesium appears to have caused recurarization in this patient. The dose of magnesium alone would not be expected to cause muscle weakness. Potentiation of neuromuscular blocking drugs by magnesium is well recognized, and we recommend its use is avoided for at least 30 min after reversal of neuromuscular block.