///2009 Abstract Details
2009 Abstract Details2019-08-03T15:55:31-06:00

Anesthetic Management of the Parturient with Ornithine Transcarbamylase (OTC) Deficiency

Abstract Number: 77
Abstract Type: Case Report/Case Series

Octav C Constantinescu M.D.1 ; Terrence K Allen MBBS, FRCA2; Maria J Small MD, MPH3; Ashraf S Habib MBBCh, MSc, FRCA4

Introduction: Ornithine Transcarbamylase (OTC) deficiency is an X-linked inborn error of metabolism of the urea cycle which may lead to fatal hyperammonemia during periods of catabolic stress such as pregnancy, labor, surgery and infection. Clinically it is characterized by hyperammonemia and encephalopathy and may present with headaches, vomiting, lethargy, ataxia and altered mental status. OTC has been associated with postpartum seizures, coma and death.(1) We present the peripartum management of a parturient with OTC deficiency.

Case Presentation: A 43-year-old G5P0 with a BMI of 28 kg/m2 and a history of OTC deficiency presented for induction of labor at 37 weeks for mild pre-eclampsia and a fetal arrhythmia. Although she was diagnosed with OTC deficiency since her early teens, she only became symptomatic in her 30s and had recurrent hospitalizations for severe hyperammonemia. She had an episode of confusion and altered mental status at 12 weeks gestation which required hospitalization and treatment with 10% DW and L-Arginine. Antenatally a low protein diet and lactulose, L-carnitine and L-citrulline were the mainstay of therapy. Urine organic acids, plasma amino acids, ammonia, and plasma L-carnitine levels were monitored throughout pregnancy to guide protein intake. Her planned anesthetic management included the early provision of epidural analgesia to attenuate the catabolic stress of labor. Serum ammonia and glucose levels, liver function tests and urine organic acids were measured on admission and found to be normal. She was started on a 10% DWNS infusion at 144 ml/h to prevent excess protein metabolism. An emergency protocol was in place to treat symptomatic hyperammonemia which involved the initial administration of L-Arginine or emergent hemodialysis. She subsequently had an emergency cesarean delivery under spinal anesthesia for a non-reassuring fetal heart rate tracing following failed induction of labor. Hyperbaric bupivacaine 12 mg, 15 mcg fentanyl and 150 mcg preservative-free morphine were administered intrathecally. A prophylactic phenylephrine infusion initiated at 50 mcg/min was administered with 2 L of lactated ringers to prevent maternal hypotension. The 10% DWNS infusion was continued at 144 ml/h perioperatively until a regular PO diet was resumed postpartum. She delivered a 2630 g female infant with Apgar scores of 9 and 9 at 1 and 5 minutes. Serum ammonia levels peaked at 72 μmol/dL (normal range 16-50 μmol/dL) on the 3rd postoperative day. She remained asymptomatic and was discharged from hospital on the 3rd postoperative day.

Discussion: The management of the parturient with OTC deficiency is multidisciplinary and should be aimed at reducing catabolic stress and preventing acute hyperammonemia. The anticatabolic effect of neuraxial anesthesia may make it a useful adjunct for both labor and cesarean delivery in this patient population.(2)

1. Obstet Gynecol 2003;102:1212-5

2. Anesth Analg 2005;101:1202-1208

SOAP 2009