Brown Pediatrics

Brown's Pediatric Residency Blog

Month: May 2017

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

 

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