When you hear hooves...

When you hear hooves...

A 2 week old baby boy is brought to the ED with concerns of poor feeding, vomiting and sleepiness.
— PmHx: Born at home, First pregnancy

Observations

A – Moaning

B – RR 60, sats 98% in air

C – HR 180, CRT 4 secs centrally, BP unable to record 

D – Quiet but responsive, BM 1

E – Temp 38.5°C, no rashes 

Clinical Findings

  • Mottled

  • Jaundiced

  • Never regained birth weight 


Why We Simulated

Inborn errors of metabolism are rare but life threatening and a proportion are seen presenting as Sudden Unexplained Death in Childhood (SUDIC) cases. Although some are detected through newborn blood spot screening (which includes a panel of 6 metabolic conditions,) others will present with non-specific symptoms of poor feeding and vomiting. Our mantra in the unwell neonate is ‘Think sepsis, think cardiac, think metabolic.’ In other words, if you do not consider the rare possibility of a metabolic disorder you may miss it.

Inborn errors of metabolism can be divided broadly into 3 groups:

  • Problems with carbohydrate metabolism. The patients will have hypoglycaemia, raised serum ketones (due to fat metabolism), hepatomegaly and reducing sugars in their urine. Examples of such conditions include glycogen storage disease, galactosaemia and fructose intolerance.

  • Problems with fat metabolism. These children cannot cope with periods of fasting (for example during intercurrent vomiting illness) because they cannot break down fats when there is a lack of ingested carbohydrate. Investigations in such cases will show hypoglycaemia with no ketone production.

  • Problems with protein metabolism. Defects within this group can be urea cycle or organic acid defects. Raised ammonia levels and metabolic acidosis in conjunction with specialised tests of amino acid and organic acid serum and urine profiles are diagnostic.

These are complex disorder which require specialist investigations which take time to process and the underlying diagnosis will not be made in the ED. However, the acute management of such conditions is relatively straightforward:

  1. Stop feeds: This will stop driving further accumulation of toxic substances.

  2. Gain IV access and take a blood gas sample: If the child is hypoglycaemic, use the ‘hypo box’ in the paediatric ED which contains all the blood bottles, pre-labelled forms and instructions to perform a screen for metabolic conditions.

  3. Correct hypoglycaemia and treat shock if present: Follow acute fluid resuscitation with IV dextrose infusion to provide a safe substrate for further metabolism.

Children with a known metabolic condition often have an emergency regime to follow – follow it! 

Further Reading:


Learning Outcomes

  1. In any unwell neonate always consider a broad differential diagnosis including sepsis, cardiac and metabolic conditions.

  2. In the ED, treatment of shock with ongoing IV fluid management, stopping feeds and correction of hypoglycaemia will help to stabilise children with suspected metabolic conditions. Identifying the underlying metabolic disorder often requires further testing and specialist review.

  3. Galactosaemia can present with a triad of poor feeding with vomiting, jaundice and E Coli sepsis.

Positive Feedback

  • Structured A to E assessment.

  • Excellent use of 'Quick Summary' to update team members of current clinical situation when they had been away from bedside preparing drugs.

  • Good parental explanation.

Edit & Peer Review by Gareth Lewis

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