After completing this article, readers should be able to: 1. Describe the metabolic acidosis that may be seen in urea cycle defects. 2. Delineate the most important factor in determining neurologic outcome in urea cycle defects. 3. Explain the factors that affect the blood ammonia concentration in continuous renal replacement therapy (CRRT). 4. Delineate the most difficult issue in pursuing CRRT in neonates. 5. Describe the morbidities associated with CRRT. MP was born at 39 weeks' estimated gestational age by vaginal delivery to a 35-year-old gravida 3 para 2 woman who had an uncomplicated pregnancy. The 3- and 6-year-old female siblings of the patient were healthy. Apgar scores were 8 at 1 minute and 9 at 5 minutes. The newborn was discharged to home after a 2-day stay in the well baby nursery during which time she appeared to be alert and was breastfeeding appropriately. She presented to the emergency department less than 1 day later after her parents noted increasing lethargy and very poor feeding at home. She was admitted to the neonatal intensive care unit (NICU). Results of a complete blood count with differential count and C-reactive protein evaluation were unremarkable, but the patient progressed to worsening lethargy, respiratory failure, and abdominal distension requiring intubation within hours of admission. The anterior fontanelle was soft on admission physical examination. Further testing revealed a base deficit of 6.1 on arterial blood gas, serum ammonia level of 810 mcmol/L (1,134 mcg/dL), serum lactate level of 5.6 mmol/L (5.6 mEq/L), and serum pyruvate level of 0.06 mmol/L. Results of liver function tests were abnormal, and the infant had a prothrombin time of 35.9 seconds, a partial thromboplastin time of 54.3 seconds, and a fibrinogen concentration of 1.75 g/L (175 mg/dL). Genetic and nephrology consultations were requested immediately. Additional metabolic studies were obtained, including measurement of plasma amino …
Read full abstract