Jannet J. Lee-Jayaram, MD; Ghazala Sharieff, MD

Disclosures

March 29, 2010

Case Presentation

A 4-day-old boy presented to an urban pediatric emergency department (ED) with chief complaints of sleeping too much and not eating. He was born via normal spontaneous vaginal delivery with no complications. His mother was under normal prenatal care and was VDRL test and HIV negative, rubella immune, and group B beta-hemolytic Streptococcus status negative. The patient had an unremarkable newborn nursery stay for 2 days and was discharged home. His mother stated that he had initially been a voracious feeder of formula, but has lost interest in feeding during the past 24 hours. On the day of presentation, he was asleep for most of the day and drank less than an ounce of formula. When she tried to wake him to feed, he would only wake briefly to try to feed and then fall back asleep. He had 3 small wet diapers the entire day, and his mother brought him in due to concern for his hydration status.

On review of systems, she denied any fever, vomiting, diarrhea, trouble breathing, rashes, skin color change, seizures, or bleeding. She denied feeding him anything other than regular cow's milk formula. She denied giving him any medications. Family history was negative for any consanguinity, early deaths, or other diseases. The patient's mother was his primary caretaker, and he lived at home with his mother, father, and 2 older sisters who were both healthy. He was not on any medications, had no known allergies, and had received his first hepatitis B immunization in the newborn nursery.

Physical Examination

Vitals: temperature, 37°˚C (rectal); heart rate, 155 beats per minute; respiratory rate, 58 breaths per minute; blood pressure, 80/55 mm Hg; room air oxygen saturation, 98%; weight, 3.5 kg

General: Somnolent; briefly arousable with stimulation

HEENT: anterior fontanelle open, soft, and flat; no scleral icterus; pupils equal, round, and reactive to light; normal facies; oropharynx clear; mucous membranes tacky

Neck: full passive range of motion; no paradoxical irritability

Cardiovascular: regular rate and rhythm; no murmurs, rubs, gallops, or thrills

Lungs: hyperpneic with clear breath sounds bilaterally; good air entry, no wheeze; occasional grunting

Abdomen: soft, nontender, nondistended, with no masses or organomegaly

Genitourinary: normal uncircumcised penis; Tanner stage I; bilaterally descended testes

Extremities: capillary refill brisk; no edema or deformities

Neurologic: decreased tone when unstimulated; brief cry with increase in tone of extremities upon stimulation; somnolent

Skin: no jaundice, rash, or other lesions

ED Course

The patient was noted to be somnolent upon arrival to the ED, but responded to stimulation and was maintaining normal oxygenation on room air. Due to lethargy, a sepsis work-up was initiated. An intravenous (IV) catheter was placed, and the patient received a 20-mL/kg bolus of normal saline. A chest x-ray, bedside glucose, complete blood count (CBC), metabolic panel, venous blood gas, ammonia, urinalysis, urine culture, blood culture, cerebrospinal fluid (CSF) panel, and CSF culture were performed. Throughout his ED stay, the patient remained hyperpneic and somnolent but with otherwise stable vital signs. He was started on maintenance IV fluids, and was given ampicillin and gentamicin for coverage of possible neonatal sepsis while cultures were pending. When the results of his ammonia level returned, he was expeditiously admitted to the pediatric intensive care unit for further management and evaluation.

Laboratory and Radiographic Studies

Chest x-ray: Clear lungs; no infiltrates; normal cardiothymic silhouette; normal bony structures

Venous blood gas: pH 7.51; pC02 30 mm Hg BE -1

CBC: WBC 9.8; Hgb 13.6; PLTs 380,000 (52% segs, 28% lymphs, 15% monos)

Metabolic panel: Na 140; K 4.0; Cl 109; CO2 23; glucose 95; BUN 7; Cr 0.2

Urinalysis: yellow; specific gravity, 1.020; trace protein; small ketones; negative leukocyte esterase; negative nitrites; 3 RBC/hpf; 5 WBC/hpf; negative glucose

CSF analysis: clear fluid; 1 WBC (mono); 0 RBC; glucose 75; protein 25

Ammonia level: > 800 (ref 29-57) µmol/L

Hospital Course

The patient was admitted to the pediatric intensive care unit that evening. He was maintained on IV fluids at 1.5 times his maintenance rate of D10 one quarter normal saline. He was intubated both for his severe somnolence and in anticipation of needing sedation for placement of central lines. For his severe hyperammonemia with impending coma, the initial plan was to start him on hemodialysis. However, due to his small size, the intensive care unit team could not cannulate his vessels with dialysis catheters, and surgeons were consulted for emergent cannulation of his carotid vessels. He was placed on extracorporeal membrane oxygenation in connection with continuous veno-venous hemofiltration to reduce his serum ammonia level precipitously. He was maintained on extracorporeal membrane oxygenation in the pediatric intensive care unit for several days before being transferred to the general pediatric floor. On the second day of hospitalization, his pediatrician informed us that the state screening board had called with urgent values from his newborn screening test. Following a consultation with metabolic specialists, the patient was diagnosed with ornithine transcarbamylase deficiency, an X-linked urea cycle defect. After a prolonged hospital course, he was discharged from the hospital on a high-calorie, protein-restricted formula with supplementation of essential amino acids. His mother was advised that the long-term effects of the hyperammonemia could not be predicted until the child grew older and his neurologic development could be tracked.

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