Neonatal Hyperammonemia Clinical Pathway – PICU and Emergency Department

Clinical Pathways Home Emergency ICU Inpatient Outpatient Specialty Care Primary Care

Goals and Metrics

Provider Resources

Neonates with Initial Presentation
of Acute Hyperammonemia

Guidance for Referred Children

Triage (Critical/Acute)

Initial Evaluation
- History, Physical Exam
- Differential Diagnosis
Review referring hospital records, labs, imaging
Resuscitation
- Airway support as indicated
- Establish IV access
- Initial Laboratory Studies
- Initial Fluid Management
- Stop Protein intake immediately
Emergent head CT
- Preferred modality for assessing increased ICP
- Consider Fast MRI depending on child stability
Consults
- Metabolism
- Interventional Radiology
  - Central and hemodialysis access
- Nephrology
- Neonatology

Neonates with hyperammonemia are at risk for severe neurologic impairment.
Rapid diagnosis and aggressive treatment by a coordinated multidisciplinary team are critical.

Priority management goals:
Obtain adequate vascular access
Initiate metabolic therapy
Provide Continuous Renal
- Replacement Therapy

Admit to PICU

Ready Giraffe^® warmer bed, temperature probes available
Consider intubation
- Use cuffed ETT for tight control of CO₂
- Facilitate central catheter placement

Lower Risk
Ammonia level < 500 umol/L
and/or
Mental status WNL

Higher Risk

Ammonia level ≥ 500 umol/L or
Mental status changes and/or
Tachypnea, respiratory alkalosis and/or
Evidence of cerebral edema, seizures

GIR
Glucose infusion rate goal: 10-15 mg/kg/min
Initiate with Metabolism Guidance
- Arginine therapy
- Sodium Phenylacetate + Sodium Benzoate (Ammonul^®)
Avoid fever

GIR
Glucose infusion rate goal: 15-20 mg/kg/min
Initiate
- Arginine therapy
- Sodium Phenylacetate + Sodium Benzoate (Ammonul)
Prepare for CRRT (Continuous Renal Replacement Therapy) using only a Prisma CRRT machine (ammonia clearance may be inadequate with Aquadex™ or Carpediem™)
Access
- Obtain central access and HD Catheter
Initiate CRRT
- Indications include encephalopathy or ammonia > 1,000 or poor response to initial therapies
Avoid fever
- Consider Targeted Temperature Management

Continued Medical Management
Lab Monitoring	Lower risk: Ammonia level every 3-4 hrs Higher risk: Ammonia level every 1-2 hrs initially (use STAT order priority) Lab frequency may be spaced once ammonia has decreased and child has stabilized
Indications for CRRT	Consider if ammonia level not improving after 1-2 hours of medical management or Persistent encephalopathy If there are no relative contraindications (infant size, presence of coagulopathy)
Glucose Management	For persistent hyperglycemia > 200 mg/dL, do not decrease GIR Start insulin infusion 0.01 units/kg/hr Titrate by 0.01 unit/kg/hr to maintain euglycemia (goal: 100-200 mg/dL)
Continued Care	Following stabilization with improving labs and physical exam, care plan is coordinated by Critical Care Team with Metabolism and Nephrology consultation

Posted: August 2020
Revised: March 2023
Authors: K. McKenna, MD; B. Laskin, MD; J. Fitzgerald, MD; S. Vatsky, DO; A. Bustin, PharmD

Evidence

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The clinical pathways are based upon publicly available medical evidence and/or a consensus of medical practitioners at The Children’s Hospital of Philadelphia (“CHOP”) and are current at the time of publication. These clinical pathways are intended to be a guide for practitioners and may need to be adapted for each specific patient based on the practitioner’s professional judgment, consideration of any unique circumstances, the needs of each patient and their family, and/or the availability of various resources at the health care institution where the patient is located.

Accordingly, these clinical pathways are not intended to constitute medical advice or treatment, or to create a doctor-patient relationship between/among The Children’s Hospital of Philadelphia (“CHOP”), its physicians and the individual patients in question. CHOP does not represent or warrant that the clinical pathways are in every respect accurate or complete, or that one or more of them apply to a particular patient or medical condition. CHOP is not responsible for any errors or omissions in the clinical pathways, or for any outcomes a patient might experience where a clinician consulted one or more such pathways in connection with providing care for that patient.