[Anesthetic management of a patient with acute intermittent porphyria]

A 40-y-o female was scheduled for modified radical hysterectomy and pelvic lymphadenotomy for malignant ovarian tumor. Her past history revealed frequent episodes of reddish discoloration of her urine after physical strain. Her blood and urine samples were submitted for chemical analysis of metabolites of hemoglobin and porphyrin on suspicion of acute intermittent porphyria (AIP). Since these examinations took some days, the patient had to undergo the operation before the results arrived. To prevent an acute exacerbation of possible AIP, some anesthetic drugs had to be avoided. After premedication with atropine 0.5 mg IM, the patient had an epidural catheter placed for later use. General anesthesia was induced with intravenous fentanyl 0.3 mg IV, and inhalation of sevoflurane (0.5-4%) in nitrous oxide and oxygen by mask to eliminate psychological stress during the operation. Then, 0.5% bupivacaine was used through the epidural catheter to block the afferent physical stimulation from the lower half the body. Special attention was paid to stabilize the cardiovascular system. Color of the urine was carefully monitored with a densitometer to find out any early sign of a relapse of AIP during the operation. After the operation, reddish urine and rapid respiration suggested a possible exacerbation of AIP. Fluid therapy with glucose, sedation with chlorpromazine IV and an epidural infusion of buprenorphine (0.5 mg) were performed. The urine became clear several days after the operation and the postoperative course was uneventful. Anesthetic management of patients with AIP is discussed along with the introduction of pertinent literatures.