UMEM Educational Pearls - By Danielle Devereaux

Hot off the press! Pediatrics March 2014 just published results of a meta-analysis that compared 1 or 2 dose regimens of Dexamethasone versus 5 day course of Prednisone/Prednisolone for management of acute asthma exacerbations in pediatric patients. The results showed that Dexamethasone was as efficacious as the longer course of Prednisone. End points used were return trips to the emergency department and hospital admissions. On further review of the literature, parents tend to prefer the shorter duration of therapy with Dexamethasone. Also, there is less vomiting associated with Dexamethasone. There have been several articles published that show Dexamethasone is more cost-effective than Prednisone. Bottom line: consider giving single dose of Dexamethasone in the ER and then sending patient home with 1 additional dose.

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Inborn errors of metabolism (IEM) are rare, each typically affecting 1 in 5000 to 1 in 100,000 children, BUT collectively these disorders are more common because there are so many. If you are lucky…when they present to the ED they come with a letter from Dr. Greene (our world renowned metabolic geneticist) detailing exactly what to do. The rest of the time…you are on your own. Think about IEM in any neonate or child with history of feeding difficulties, failure to thrive, recurrent vomiting, unexplained altered mental status and/or acidosis. Pay particular attention to feeding difficulties that appear with changes in diet: switch from soy to cow’s milk formula (galactose), addition of juice or fruit or certain soy formulas (fructose), switch from breast milk to formula or foods (increased protein load), and longer fasting periods from sleeping or illness.

For this pearl, we will focus on primary hyperammonemia from an enzymatic block in ammonia metabolism within the urea cycle. It is important to remember that secondary hyperammonemia can result from metabolic defects such as organic acid disorders, fatty acid oxidation disorders, drugs that interfere with urea cycle, or severe liver disease. Amino acids liberated from excess protein breakdown (stress of newborn period, infection, injury, dehydration, surgery, or increased intake) release nitrogen which circulates as ammonia. Ammonia is then converted to urea via the urea cycle and excreted in the urine. With urea cycle defects (UCD) there is an enzymatic block in the cycle that results in accumulation of ammonia which has toxic effects on the CNS especially cerebral edema. The most common UCD is ornithine transcarbamylase deficiency followed by argininosuccinic academia, and citrullinemia.

Clinical presentation includes poor feeding, lethargy, tachypnea, hypothermia, irritability, vomiting, ataxia, seizures, hepatomegaly, and coma. Hyperammonemic crises in neonates mimic sepsis! If you think about an IEM in your differential, send plasma ammonia (1.5 mL sodium-heparin tube on ice STAT), plasma amino acids, and urine organic acids. Other helpful labs include blood gas, CMP, urinalysis (looking at ketones), lactate, plasma acylcarnitines, and newborn screen if not already sent. Plasma ammonia is a direct index of CNS toxicity and important to follow for acute management. Serum level > 150 in sick neonate or > 100 in sick infant/child is concerning for IEM. The presence of hyperammonemia and respiratory alkalosis suggest urea cycle defect. The presence of metabolic acidosis and hyperammonemia suggests organic acid disorder.

Immediate treatment of hyperammonemia is critical to prevent neurologic damage. Cognitive outcome is inversely related to the number of days of neonatal coma caused by the cerebral edema.

1. Stop all protein intake! You need to stop catabolism.

2. Start D10 at 1.5 times maintenance rate with GIR at least 6-8. Start intralipids 1-3g/kg/day when able (typically in the ICU after central line placed).

3. Give ammonia scavenger medications sodium benzoate and sodium phenylacetate. These are available commercially as Ammonul.

     a. 0-20kg: 2.5mL/kg IV bolus over 90 min followed by same dose as 24 hr infusion

     b. >20kg: 55 mL/m2 IV bolus over 90 min followed by same dose as 24 hr infusion

4. HEMODIALYSIS! Dialysis is the most effective way to remove ammonia and should be done when level > 300. The decision to hemodialyze is crucial in preventing irreversible CNS damage; when in doubt in the face of elevated ammonia, HEMODIALYZE!

Head lice infestation is a common problem in the United States with treatment costs estimated at 1 billion dollars and cases affecting millions of children each year.  Many of these children present to the ED for care...lucky us!  Traditional therapies containing permethrin and pyrethrins are having increased rates of treatment failure likely secondary to increasing resistance and medication noncompliance.  The typical first line agents require multiple doses.  There are safety concerns regarding therapies that contain malathion and lindane in children.  Is there another option?  Topical ivermectin 0.5% lotion applied to scalp in a single dose has been shown to be effective and safe for treatment of head lice infestation in children older than 6 months.  It was FDA approved at the end of 2012.  Considerations include cost. Sklice lotion is expensive!  

The NEJM article was considered an "editors pick"  by the AAP as one of the best articles of 2012-2013.

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How many times have you been frustrated in the peds ED when you have a child with a URI that has a significant night time cough and you feel like you have nothing to offer them for symptom control?  The parent is frustrated because the child is not sleeping which means they are not sleeping and they are looking at you for help.  We all know that OTC cough and cold medications are not helpful and may be harmful in children <2 yrs old and should be used with caution in children <6 yrs old.  So what can you do?  You can recommend a course of HONEY at night.  Of course this does not apply to children < 1 yr who are at increased risk of botulism.  A recent double-blind placebo-controlled trial published in Pediatrics in 2012 demonstrated reduced night time cough and subjective improved sleep quality in children age 1-5 who were given honey compared to placebo.  This study supports previous less rigorous publications that found honey was an effective remedy on cough in children.  Mechanism for honey's beneficial effect on cough is unknown but possibly related to close anatomic relationship between sensory nerve fibers that initiate cough and gustatory nerve fibers that taste sweetness.  Of note, a recently published survey in Pediatric Emergency Care revealed that 2/3 of parents were unaware of the FDA guidelines regarding OTC cough and cold remedies in children!  After you recommend HONEY for night time cough, take an extra minute and educate your parents about the potential dangers of cough and cold medicines in small children!

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