NM-362
Anesthetic Management of a Patient with Argininosuccinate Lyase Deficiency
Kuebler C, Scales L, Sisk J
University of Oklahoma, Oklahoma City, Oklahoma, USA
Argininosuccinate Lyase Deficiency (ASL) is a rare (1/70,000) defect in urea cycle metabolism which may lead to life threatening hyperammonemia. Existing anesthesia literature provides little guidance for the management of these patients and careful planning in conjunction with a clinical geneticist is mandatory for safe peri-operative care. We present the case of a 7-month-old boy with a history of ASL presenting for bilateral myringotomy tubes.
Argininosuccinate Lyase Deficiency is the result of a mutated or deficient argininosuccinate lyase enzyme. A defective or deficient arginosuccinate lyase enzyme leads to inadequate ureagenesis, accumulation of argininosuccinic acid, and deficient endogenous arginine. Catabolic states such as sepsis, surgery, fasting and heavy exercise may lead to toxic ammonia accumulation.
Typical surgeries include ENT procedures which may be performed to decrease the risk of infection leading to metabolic crisis. Anesthesia for Dental Procedures may be required due to developmental delay. Some children may require liver transplant for recurrent hyperammonemia and/or liver failure. There are insufficient data to support the superiority of any particular anesthetic agent or technique. ENT or Dental Procedures with potential bleeding into the GI tract should utilize OG tubes and/or Throat Packs to minimize the amount of blood ingested as this protein load may represent a metabolic burden leading to decompensation. General anesthesia should be used with caution and post-operative monitoring should involve a Clinical Geneticist.
Life threatening hyperammonemia may progress to coma, brain damage and death in a matter of hours. This may be triggered by fasting, poor feeding, surgical stress, minor infections, mild dehydration, vomiting/diarrhea, medication non-compliance and diet non-compliance. Signs of metabolic crisis include anorexia, nausea/vomiting, lethargy, abnormal respirations, spasticity and hyperreflexia. Emergency treatment includes IV Intralipid therapy, correction of metabolic acidosis with sodium bicarbonate, generous IV resuscitation to correct dehydration; however, lactated ringers should be avoided. Maintenance IV fluids should include 10% Dextrose and be infused at 1.5x the maintenance rate. Critically high ammonia levels may require emergent dialysis.
The patient was admitted in consultation with clinical genetics for pre-operative IV hydration prior to being made NPO. He had an uneventful sevoflurane anesthetic supplemented by IV fentanyl. He was observed post-operatively by the clinical genetics team and discharged home the following day.
References:
1. Bachmann, C. (2003). Outcome and survival of 88 patients with urea cycle disorders: a retrospective evaluation. European Journal of Pediatrics, 162: 410–416.
2. Brusilow, SW.; Horwich, AL. Online Metabolic and Molecular Basis of Inherited Disease. 2009.
3. Erez, A., Nagamani, S. and Lee, B. (2011). Argininosuccinate lyase deficiency-Argininosuccinic aciduria and beyond. American Journal of Medical Genetics Part C: Seminars in Medical Genetics, 157(1), pp.45-53.
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