A two-week-old baby is brought to your general ICU in extremis pending transfer to a Paediatric centre. Born at term, she had been discharged well on day 5 of life. For three days she has had progressive tachypnoea, lethargy and failure to feed, and has now presented after a seizure. She has been intubated in the Emergency Department.

Blood test results taken on air prior to intubation are shown below:

Parameter

Patient Value

Adult Normal Range

OH

7.04*

7.35 - 7.45

PCO2

14 mmHg 1.9 kPa)*

35 —45 (4.6 — 6.0)

P02

80 mmHa (10.5 kPa)

Bicarbonate

5 mmol/L*

22 - 28

Lactate

8 mmol/L*

Glucose

0.9 mmol/L*

3.5 - 6.1

White Cell Count

14.7 x 109/L*

4.0 - 1 1.0

Neutrophils

27%

Lymphocytes

70%

Alanine aminotransferase (ALT)

1600 U/L*

10-55

Aspartate aminotransferase (AST)

2200 U/L*

10 —40

a) List, in broad terms, the key differential diagnoses for this presentation (20% marks)
b)    Outline your approach to differentiating between these diagnoses. (30% marks)
c)    Outline principles of early management pending transfer.    (50% marks)

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College answer

a)

Inborn error of metabolism
Sepsis (viral likely)
Cardiac disease- especially duct dependent disease  
Trauma (NAI)
Drugs / Toxins 
 

b)

History: 
Exposure to ill persons including siblings and parents.  
“Colds”, chicken pox and maternal herpes should be specifically solicited.
Maternal Group B Strep swab should be reviewed
Injury 
Cyanotic spells  Apnoeas 
Family history including infant deaths, inborn errors of metabolism (IEMs), cardiac disease, degree of consanguinity 
 
Examination: 
General exam - trauma, rash Liver edge (failure, hepatitis) Murmurs Femoral pulses 
 
Investigations: 
CXR
ECG
Ammonia
Urine amino and organic acids (if can’t be processed, take while acidotic and store) Cultures if not done
CMV, HSV PCR
Consider skeletal survey if any suggestion of injury  
Cranial ultrasound (widely available)
Echo if available 
 
c) Ongoing liaison with receiving centre.  

Restore then maintain BSL using 10% Glucose (2.5-5ml/kg 10% glucose bolus then 6mg/kg/min infusion.) 
Restore intravascular volume (even post FEAST fluid bolus reasonable)
Direct therapy if specific pathology found- e.g. alprostadil infusion if evidence of duct dependent cardiac disease

 Empiric antibiotics
Empiric antiviral given results above (acyclovir or ganciclovir)
Nil protein intake till initial metabolic results in- maintain on glucose as above

Lung protective ventilation

General ICU housekeeping. 
 
Examiners Comments: 
 
Reasonably well done. Part a) was answered better than b) and c). Some candidates did not read the question completely and described intubation of the baby. 

 

Discussion

This question, and the college answer, are weirdly identical to Question 10 from the first paper of 2015, except now they have capitalised the word "Paediatric", and in 2018 the bloods merely "show," instead of now being "shown below". What was the merit of making these changes without altering any other features of the question?  What is the significance of these changes? Surely there must be some reason behind them, because it would have required less effort to simply cut and paste the SAQ. However, this line of thinking is unproductive. Trying to get into the examiner's heads in the pursuit of some hidden eldritch meaning, there is some risk that a trainee might suddenly be confronted with the Lovecraftian cosmic horror of realising that nobody is carefully tending to the wording or syntax of these SAQs. Gibbering madness may ensue

In context of these matters, below one may see that the author has cut-and-pasted the entire discussion section from Question 10 from the first paper of 2015, with subtle changes which on the surface might appear random and cosmetic.

a) Differentials for this shock-like presentation:

Differential Diagnosis of Paediatric Metabolic Acidosis and Shock
Domain Neonate/infant age group Children older than 12 months
Vascular
  • Cardiac tamponade following congenial defect repair
  • Pulmonary embolism
  • Cardiac tamponade and pulmonary embolism 
Infectious
  • Bacterial sepsis (eg. Gp B strep)
  • Viral illness 
  • Hypovolaemia due to dehydration via diarrhoea, vomiting or failure to feed
  • Bacterial sepsis
  • Viral illness 
  • Immune compromise due to lymphoma or leukaemia
  • Hypovolaemia due to dehydration via diarrhoea, vomiting or decreased oral intake
Neoplastic
  •  
  • Haematological malignancy
Drug-induced
  • Accidental overdose through maternal excretion into milk
  • Accidental overdose
Congenital
  • Heart defect, especially duct-dependent disease
  • Complications of previously stable heart defect (eg. "Eisenmongerisation" of the right heart)
Autoimmune
  • Anaphylaxis
  • Anaphylaxis
Trauma
  • Haemorrhage
  • Neurogenic (eg. cord section)
  • Tension pneumothorax 
  • Haemorrhage
  • Neurogenic (eg. cord section)
Endocrine
or metabolic
  • Congenital metabolic pathway defect
  • Hypothyroidism
  • Hypoadrenalism
  • Severe ketoacidosis
  • Metabolic pathway defect

b) Assessment of this shock state:

Generic to the infant/paediatric population

History

  • Fever, feeding, urine output, diarrhoea, vomiting
  • Irritability, lethargy
  • Trauma
  • Potential for ingestion 
  • Vaccination history
  • Unwell contacts

Examination

  • Temperature
  • Level of consciousness
  • Peripheral perfusion, capillary refill
  • Rash
  • Skin turgor
  • Mucous membranes
  • Pulses
  • Heart rate, rhythm
  • Blood pressure
  • Respiratory rate

Investigations

  • CXR
  • ECG
  • ABG for lactate
  • FBC and blood film
  • BSL
  • EUCs, LFTs
  • Blood cultures
  • TTE
Specific for the neonatal population:
  • Maternal Group B strep swab history
  • Maternal chicken pox or herpes history
  • Rapid breathing, sweating, tiring or cyanosis while feeding
  • Antenatal care (any?)
  • History of infant death in the family
  • Cosanguineity
  • Inborn errors of metabolism
  • Congenital heart disease
  • Cardiac murmurs
  • Abdominal distension (eg. pyloric stenosis)
  • Differential cyanosis (PDA)
  • Ammonia level
  • Urinary amino acid and organic acid screen
  • CMV, HSV PCR
  • Cranial ultrasound

c) Approach to management, which is very generic:

  1. Assess the need for endotracheal intubation.
    - At this stage, senior assistance from somebody expert in paediatric critical care is required, as the intubation may be difficult.
  2. Administer 100% oxygen.
  3. Establish venous access.
    - Give a 20ml/kg bolus, FEAST be damned.
    - Inotropes and vasopressors if no longer fluid-responsive
    - Parameters guiding resuscitation (eg. lactate, haemodynamic variables, urine output) differ little from adult standards
  4. Sedation and analgesia to support tolerance of invasive therapies
    (also decreases demands on the cardiac output)
  5. Electrolyte correction
  6. Maintenance fluid:  As per college answer, "add 100 ml of 50% dextrose to 900 ml 0.9% NaCl and infuse this at 2/3 maintenance rate (16 ml/hr in this case) (accept 24 ml/hr for 1st 48 hours)". On close inspection, this concoction resembles the premixed "4% and 1/5th " bags.
    - A urinary catheter will also be required.
  7. No protein in diet until metabolic screen is cleared
    - Maintain normoglycaemia with infusion of 10% dextrose of dextrose-rich maintenance fluid
  8. Blood transfusion may not be warranted
  9. Empiric antibiotics if sepsis is suspected, within 1 hour.
    - Cultures of blood and urine.
    - Consider antivirals if there is suspicion of viral meningitis or encephalitis

References

Steiner, Michael J., Darren A. DeWalt, and Julie S. Byerley. "Is this child dehydrated?." Jama 291.22 (2004): 2746-2754.

Levine, Adam C., et al. "Empirically Derived Dehydration Scoring and Decision Tree Models for Children With Diarrhea: Assessment and Internal Validation in a Prospective Cohort Study in Dhaka, Bangladesh.Global Health: Science and Practice 3.3 (2015): 405-418.

Freedman, Stephen B., et al. "Diagnosing clinically significant dehydration in children with acute gastroenteritis using noninvasive methods: a meta-analysis." The Journal of pediatrics 166.4 (2015): 908-916.

Friedman, Jeremy N., et al. "Development of a clinical dehydration scale for use in children between 1 and 36 months of age." The Journal of pediatrics 145.2 (2004): 201-207.

Gorelick, Marc H., Kathy N. Shaw, and Kathleen O. Murphy. "Validity and reliability of clinical signs in the diagnosis of dehydration in children." Pediatrics 99.5 (1997): e6-e6.

Holliday, Malcolm A., and William E. Segar. "The maintenance need for water in parenteral fluid therapy." Pediatrics 19.5 (1957): 823-832.

Meyers, Rachel S. "Pediatric fluid and electrolyte therapy." The Journal of Pediatric Pharmacology and Therapeutics 14.4 (2009): 204-211.

Wang, Jingjing, Erdi Xu, and Yanfeng Xiao. "Isotonic versus hypotonic maintenance IV fluids in hospitalized children: a meta-analysis." Pediatrics (2013): peds-2013.

Neilson, Julie, et al. "Intravenous fluids in children and young people: summary of NICE guidance." BMJ: British Medical Journal (Online) 351 (2015).