Brown Pediatrics

Brown's Pediatric Residency Blog

Category: Neonatology

Metabolism gone wild!

Case: Last week we talked about Jane, an otherwise healthy 2-week old girl. Let’s change the story a bit to hit on another consideration in infants. Instead of simply being febrile and fussy, let’s say that she comes back to the ED, this time afebrile, but lethargic with poor cap refill. How does our differential change now?

 

 

Image Credit: Pixabay

What are the important diagnostic considerations for neonates and infants who present very ill?

  1. Infection
  2. Metabolic/Endocrinologic
  3. Trauma
  4. Cardiac
  5. Surgical emergencies

For those of you who like acronyms, consider “THE MISFITS” in neonates and young children presenting with undifferentiated shock (adapted from post on PEM Playbook)

  • Trauma
  • Heart Disease/Hypovolemia
  • Endocrine Emergencies
  • Metabolic
  • Inborn errors of metabolism (to get this acronym to work, there may be some repetition)
  • Seizures
  • Formula problems (think too little or too much water)
  • Intestinal disasters
  • Toxins
  • Sepsis (while this is last, all very sick infants/children should be evaluated/treated for sepsis)

 

Today we will focus on the emergency management of inborn errors of metabolism (IEM), specifically at the immediate recognition and management.

 

 

Epidemiology and Etiology

IEMs are Individually rare, but more common in aggregate- 1/5000 live births for any IEM (Ewing, 2009)

Helpful to lump metabolic deficiencies into 3 broad categories (Saudabray, 2002)

  1. Disorders leading to intoxication (think urea cycle defects)
  2. Disorders involving energy metabolism (think hypoglycemia)
  3. Errors involving synthesis or catabolism of complex molecules (e.g. lysosomal storage disorders)
    • Note: Disorders in this category are rarely treatable in emergency

How do these children present?

  • Deterioration of consciousness is one of the more common presentations of IEMs (El-Hattab, 2015)
    • Other presenting features include vomiting, seizures, apnea, hepatic failure, and cardiac disease (heart failure, cardiomyopathy, arrhythmias)
  • Specific Presentation Patterns (Ewing, 2009)
    • Hypovolemia, hyponatremia, hyperkalemia: Consider adrenal insufficiency
    • Metabolic acidosis, hyperammonemia, ketotic hypoglycemia: Consider an organic acid defect
    • Encephalopathy, respiratory alkalosis, hyperammonemia: Consider a urea cycle disorder
  • Remember, “As the neonate has an apparently limited repertoire  of responses to severe overwhelming illness, the predominant clinical signs and symptoms can be nonspecific like poor feeding, lethargy, failure to thrive, etc.” (Saudabray, 2002)

What is the immediate workup? (El-Hattab, 2015)

Image Credit: Pixabay

  • Primary Workup

    • Glucose
    • Blood Gas with Lactate
    • Serum Chemistry (including BUN/SCr)
    • Urinalysis
    • Complete Blood Count (CBC) and Differential
  • Secondary Workup

    • Specific Findings from Initial Workup and/or Exam
      • Hypoglycemia: insulin, cortisol, growth hormone, β-hydroxybutryate, plasma acylcarnitine profile, plasma amino acids and urine organic acids
      • Encephalopathy: ammonia, Liver “Function” Test (sp. ALT, AST, bilirubin)
      • Suspected galactosemia: urine reducing substances

How do you stabilize? (Note: Do not wait for labs to return to begin stabilization!)

Image Credit: Pixabay

  • ABCs (patients can present altered, apneic and/or in shock)
  • Recall the 2 main categories leading to emergencies: IEMs leading to intoxication and those resulting in energy defects (Ewing, 2009)
    1. Give Energy
      • Dextrose
        • Bolus as needed to treat hypoglycemia
        • Maintenance with D10 solutions
    2. Remove Toxins
      • Make NPO
      • Intravenous Fluids
        • D10 Half-normal saline run at 1-1.5x maintenance rate
      • Hemodialysis if indicated
        • Severe Hyperammonemia (Urea Cycle defects)

Next Steps?

Consultation with a metabolic specialist is essential!

  • Will help direct further diagnostic workup
  • Will help determine if further medical interventions (medications, vitamins, cofactors, etc)

 

Summary

  1. Inborn errors of metabolism present non-specifically
  2. Always consider IEM when presented with unwell neonate or infant
  3. For critically ill presentations, IEMs can be broken down into 2 main categories: Toxin Accumulation and/or Deficient Energy
    • Emergent Treatment (following ABCs) are directed at these two issues

Faculty Reviewer: Chanika Phornphutkul, MD

References

  • El-Hattab AW. “Inborn Errors of Metabolism.” Clinc Perinatol. 2015;1-27
  • Ewing, PH et al. “Evidence-Based Management Of Metabolic Emergencies In The Pediatric Emergency Department.” Pediatric Emergency Medicine Practice. 2009;6(10)1-16
  • Horeczko, Tim. “The Undifferentiated Sick Infant.” PEM Playbook.  http://pemplaybook.org/podcast/the-undifferentiated-sick-infant/. Accessed: 5/3/2017
  • Saudabray JM et al. ” Clinical approach to inherited metabolic disorders in neonates: an overview.” Semin Neonatol. 2002;7(1)3-15

 

This is… Lumbar Puncture

Case: Jane is a 2 week-old, previously healthy, ex- full term girl who presents to the ED from her PCPs office after being found to have a temperature of 102.5 rectally. On exam, she is fussy but consolable and has an otherwise normal exam.  In addition to blood and urine studies, you plan to perform a lumbar puncture. What would be other indications and even contraindications for an LP? What are the various techniques? Should you use local anesthesia?  

 

Lumbar Puncture: The basics

Indications

  • The most common indication for lumbar puncture is to diagnose meningitis (Bonadio, 2014)
    • Other indications include diagnosing: demyelinating diseases, subarachnoid hemorrhage, or idiopathic intracranial hypertension (formerly pseudotumor cerebri)

Contraindications

  • Suspected intracranial pressure elevation
  • Clinical/Physiological Instability (hypotension, respiratory distress, status epilepticus)
  • Coagulopathy
  • Infection of overlying skin

 

Basics of setup

After discussing the case with the team, you decide that Jane has no contraindications and that it is important to rule out meningitis.  What do you need, and how do you set up?

1.  Equipment

  • Most (if not all) of your equipment will be included in a commercially available tray (Figure 1 as an example).
    • In general, you will need the following
      • Spinal needle (1.5″ or 3″ depending on the patient)
      • sterile gloves and drapes
      • Povidone-Iodine scrub
      • Monometer tune (to measure CSF pressure)
      • Sterile tubes for CSF collection

 

Figure 1: LP Tray (Picture from Bonadio, 2014)

   

2. Position 

  • In the younger child, and in those you need to measure CSF pressures, the child should be placed in the lateral decubitus position
  • In older children, the seated position can also be used (Figure 2)
  • Remember, the spinal cord ends around L2. Therefore, the needle should enter the L3/4 or L4/5 disc space
    • The L3/4 disc space will be transected by the line that connects the iliac crests (as seen in Figure 2).

 

Figure 2: LP Landmarks (Picture from Bonadio, 2014)

 

Maximizing Success

As you are gathering your materials, you begin wondering what can be done to maximize the success of your procedure.

1.)  Anesthesia

  • Topical (“EMLA”) vs local (1% lidocaine infiltration)
    • Use of local anesthetic associated with an increased odds ratio (OR = 2.2) for success (Baxter, 2006)
    • Other RCTs (Pinheiro et al, 1993; Nigrovic, 2007) found that local infiltration did not increase success, but statistically decreased the amount of struggling in infants.
      • Note: Despite not finding any differences in success rates between the two methods, it is important to note that local infiltration did not lead to decreased success (concern for a loss of landmarks, etc).

2.) Early stylet removal (“Cincinnati” Method)

  • In this method, the stylet is removed after puncturing the epidermis
    • Baxter et al found a trend towards increased success in residents employing this method, but this was not statistically significant (Baxter, 2006)
    • Nigrovic et al did find an association between leaving the stylet in and with the composite outcome of traumatic or unsuccessful lumbar puncture (Nigrovic, 2007)

Conclusion: Use an anesthetic (topical or local infiltrate) and consider removing the stylet early

 

Now that we know what we need, where we need to go, and what helps maximize success, how do we do the procedure?

 

NEJM Tutorial

https://www.youtube.com/watch?v=weoY_9tOcJQ

Another Example from EM:RAP

Video: https://www.emrap.org/

Faculty Reviewer: Jeff Riese, MD

References

  • Baxter AL et al. “Local Anesthetic and Stylet Styles: Factors Associated with Resident Lumbar Puncture Success.” Pediatrics. 2006;117(3)876-881
  • Bonadio W. “Pediatric Lumbar Puncture and Cerebrospinal Fluid Analysis.” The Journal of Emergency Medicine. 2014;46(1)141-150.
  • Nigrovic et al. “Risk Factors for Traumatic or Unsuccessful Lumbar Punctures in Children.” Annals of Emergency Medicine. 2007;49(6)762-771
  • Pinheiro JM et al. “Role of Local Anesthesia During Lumbar Puncture in Neonates” Pediatrics. 1993;91(2)379-82

 

“Water, water, everywhere…”

woman-and-baby

 

Case: Zoe is a 10 day old ex- full term female, born to a G1P0 →1 presenting with feeding difficulties. Per her mother, she is exclusively breastfed and had initially had been doing “ok” but for the last couple days, has been more sleepy than usual and not feeding as well. She also notes that during this time, her eyes have become a bit more yellow.

 

On exam, you note an infant in no distress, but she sleeps comfortably through your exam. Jaundice is appreciated. Vitals are normal, but you note she has lost 12% of her birth weight. Her HEENT is notable for a sunken anterior fontanelle. Her exam is otherwise benign. Concerned for hyperbilirubinemia and dehydration, you order a complete metabolic panel, which, among other abnormalities, is significant for a serum sodium of 165 meq/L.

 

Why is her sodium so high?

Diagnosis: Severe neonatal hypernatremic dehydration

 

Pathophysiology

  • In this case, the most likely etiology is ineffective breastfeeding (also termed lactation failure), which is a rare, but increasing cause of hypernatremic dehydration (Mortiz et al, 2002)
  • In all humans (not just neonates), hypernatremia results from one of two mechanisms: inadequate access to free water and/or an inability to concentrate urine
  • Breastfeeding failure leads to inadequate fluid intake, but is also related to the higher concentration of sodium in breast milk (Morton, 1994)

 

How do patients present? (Moritz et al, 2005)

scaleOver 70% of patients had > 10% weight loss

 

Signs at Presentation

% Of Infants (n=70)

Jaundice 81
Poor PO Intake 61
Decreased Urine Output 36
Fever 20

Table Adapted from Moritz et al, 2005

 

How common is this problem?

  • Neonatal hypernatremic dehydration is rare. A review of admissions to a major children’s hospital found that over 4 years, 1.9% of term and near term infants were admitted for hypernatremic dehydration (Mortiz et al., 2005)
  • Most commonly affects primiparous mothers

 

How should we treat?

  • The goal of treatment is to lower serum sodium in a slow and controlled fashion
  • Conventional teaching states that sodium should not be lowered faster than 0.5mEq/hr and in fact, recent studies suggest that correction faster than 0.5mEq/L/hr is independently associated with poor neurologic outcomes and seizures (Bolat et al, 2013)
  • Specifics (based on protocol detailed in Bolat et al)
    • Emergency Phase
      • Correct shock immediately (within 30 mins) with 10-20 cc/kg 0.9% saline
    • Rehydration Phase
      • Calculated Free Water Deficit
      • Composition of fluid for rehydration is dependent on serum sodium; remember, in patients with high serum concentrations, “normal saline” will be hypotonic (154 meq/L)
      • Serum sodium should be decreased by 0.5meq/L/hr over the first 24-48 hours
      • If a patient is urinating, add 40 meq potassium to fluids

 

What are the neurological outcomes?

  • In the aforementioned study (Bolat et al, 2013), researchers found that presenting serum sodium >160 meq/L was an independent predictor of mortality (OR: 1.9) and correction faster than 0.5 meq/hr was independently associated with an increased risk of seizures (OR: 4.3)
  • At 6 months of age, patients were screened with the Denver Developemental Screening Test II. Serum sodium > 165 meq/L on presentation was associated with worse outcome.

Conclusions

  • Neonatal hypernatremic dehydration is a rare complication of exclusive breastfeeding, primarily seen with primiparous mothers and  can have devastating consequences
  • Clinicians need to be aware of this complication and ensure infants  who are exclusively breastfed are followed closely to ensure adequate breastfeeding and weight gain
  • If hypernatremic dehydration is encountered, it is imperative to 1.) treat shock initially and 2.) ensure that serum sodium is NOT corrected faster than 0.5 meq/hour

Resident Reviewer: Marie Carillo, MD

References

  • Ahmed A et al. “Complications Due to Breastfeeding Associated Hypernatremic Dehydration.” Journal of Clinical Neonatology. 2014;3(3):153-157
  • Bolat F et al. “What Is the Safe Approach for Neonatal Hypernatremic Dehydration?” Pediatric Emergency Care. 2013;29(7):808-813
  • Moritz ML et al. “Breastfeeding-Associated Hypernatremia: Are We Missing the Diagnosis?” Pediatrics. 2005;116(3):e343-e347
  • Moritz ML et al. “Disorder of Water Metabolism in Children: Hyponatremia and Hypernatremia.” Pediatrics in Review. 2002;23(11):371-380
  • Morton J. “The Clinical Usefulness of Breast Milk Sodium in the Assessment of Lactogenesis” Pediatrics. 1994;93(5):802-806

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