Perioperative management for a patient with hypermagnesemia-induced shock with perforative peritonitis

We present a case of hypermagnesemia accompanied by perforative peritonitis. A 79-year-old woman took magnesium citrate as part of the pretreatment on the day before a scheduled colonoscopy. She developed nausea and muscle weakness, and she was complaining of left abdominal pain. Consciousness gradually worsened and she developed shock. Intestinal obstruction was recognized on abdominal X-ray and computed tomography (CT), and peritonitis was suspected. An exploratory laparotomy was scheduled for diagnosis and treatment. In the operating room, arterial blood gas analysis showed metabolic acidosis and hypermagnesemia (Mg: 2.75 mmol/l, normal range: 0.1-1.5 mmol/l). On laparotomy, adhesion around the sigmoid colon and turbid ascites were recognized. But we could not detect the apparent region of perforation. Based on these findings and the presence of hypermagnesemia, we diagnosed that the shock was caused by peritonitis due to intestinal micro-perforation, and by hypermagnesemia due to absorption of laxative. We started to treat for metabolic acidosis, and to manage the hypermagnesemia by calcium hydrochloride administration and by continuous hemodiafiltration after the operation. On day 4 of the illness, the plasma Mg level was normalized. She was extubated on day 12, and discharged on day 84. This case with complicated clinical symptoms reaffirms the difficulty and importance of making a diagnosis quickly by collecting various data.