[Hyperthermia and metabolic acidosis during subtotal thyroidectomy for a patient with Basedow's disease].

A 32-year-old man underwent subtotal thyroidectomy for Basedow's disease under general anesthesia. Preoperatively, the free thyroxine (fT4) and free triiodothyronine (fT3) levels were suppressed and thyroid stimulating hormone level was elevated with administration of iodine and propylthiouracil. Heart rate was 52 beats x min(-1) in sinus rhythm. General anesthesia was induced with fentanyl, propofol and vecuronium, and maintained with nitrous oxide, oxygen and sevoflurane. Systolic blood pressure was controlled within 100 and 130 mmHg. Rectal temperature was 36.5 degrees C after anesthesia induction, gradually rising at a range of 0.4 and 0.7 degrees C per hour, up to 38.6 degrees C four hours after the operation. Arterial blood gas showed bicarbonate 17.1 mEq x l(-1) and base excess -8.1 mmol x l(-1). The metabolic acidosis with normal anion gap lasted during and after the operation. We cooled his body with cold acetyl linger fluid and cooling mattress, and administered sodium bicarbonate. Heart rate increased to 96 beats x min(-1) before the end of operation. Subtotal thyroidectomy was finished in 5 hours 16 minutes. The amount of blood loss was 950 ml. Postoperatively, the serum fT4 and fT3 were suppressed. The serum creatine kinase and lactate dehydrogenase levels increased slightly. He did not show muscle rigidity and neurological disorders. We suspect that he has developed thyroid storm-like symptoms such as hyperthermia and tachycardia induced by subtotal thyroidectomy. Metabolic acidosis might be the result of distal tubular acidosis, which rarely accompanies Basedow's disease. Arterial blood gas analysis and urinalysis should be performed, preoperatively.