[A case of prolonged apnea probably caused by vecuronium potentiated with hypermagnesemia]

A 73-year-old female weighing 41 kg who had undergone ilecolostomy under general anesthesia showed extremely prolonged apnea. Despite only 7 mg of vecuronium, she needed postoperative mechanical ventilation for more than 24 hours. A postoperative examination revealed hypermagnesemia, which probably potentiated the effect of vecuronium. Her hypermagnesemia might be caused by chronic renal failure with hypocalcemia and administration of magnesium sulfate as a cathartic. Plasma magnesium concentration should be measured perioperatively in all surgical cases.