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Understanding Pediatrics: Hydration, Vomiting/GERD, Constipation in Pediatrics

Approach to Hydration

History to determine severity of dehydration:

  • Level of activity?
  • Taking solids and fluids by mouth?
  • Urine output?

Physical exam:

  • Decreased level of consciousness / decreased activity
  • Weight before and after illness
  • Low BP, high heart rate, weak pulses
  • Dry mucous membranes, cracked lips, fissures on tongue
  • Skin turgor (> 2 seconds), capillary refill, mottling of skin, cool extremities

Oral rehydration and solids

  • Quantity of fluids
    • Initially 50 – 100 mL/kg over the span of 2-4 hours to replace fluid deficit
    • Subsequent diarrhea – 10 mL/kg per watery stool
    • Subsequent vomiting – 2 mL/kg per episode of vomiting
  • Types of solutions
    • AVOID solutions with low sodium content such as
      • Tap or distilled water
      • Sports beverages
      • Apple juice
      • Pop
      • Ginger ale
  • Solids
    • AVOID only providing BRAT diet (too restrictive)
    • AVOID sugary or fatty foods which can worsen diarrhea

IV rehydration in severe cases

  • Resuscitation
    • If patient requiring fluid boluses to replace a severe fluid deficit:
      • Large bore peripheral IV within 90 seconds
      • If cannot place peripheral line within 90 seconds then try central line if adolesccent or older, or intraosseous line (IO) if younger or in severe shock of any age
        • IO becomes progressively more difficult to do in older children and adults as the tibia BM cavity becomes smaller and the cortex of the bone becomes thicker
        • Sites for IO:
          • Distal femur
          • Proximal and distal tibia
          • Iliac crests
      • 20 mL/kg per boluses over 5 to 20 minutes if signs of shock
      • 10 ml/kg per bolus in certain circumstances
      • Fluid choice:
        • Normal saline
        • Ringers lactate
        • Plasmalyte (balanced electrolyte solution)
        • Avoid dextrose in a fluid bolus because it can cause hyperglycemia at this volume
      • Reassess vitals and physical exam after each bolus
      • A patient can receive up to 60 mL/kg if no signs of fluid overload before starting inotropic support
    • Calculating volume deficit
      • Estimate the degree of volume deficit based on physical exam
        • Minimal < 3 % dehydrated
        • Mild/moderate 3 – 10 % dehydrated
        • Severe > 10 % dehydrated
      • E.g. 20 kg patient is severely dehydrated
        • 10 % dehydrated
        • Remember 1 kg = 1 L
        • Her healthy pre-dehydration weight must be 20 x 1.10 = 22 kg
          • Which means the patient has lost 2 kg of water weight from her illness
          • Her fluid deficit is 2 L
        • Subtract the volume of any boluses she has received so far
        • For instance, if she already received a 300 mL bolus then we would do 2000 mL – 300 mL = 1700 mL
        • Her final fluid deficit is 1700 mL
        • We can give this volume back in the form of boluses and an infusion rate, but if you do an infusion rate you have to make sure you add it with their maintenance rate as well
  • Maintenance
    • Majority of pediatric patients (excluding newborns) will be on D5NS (D5 normal saline)
      • KCl can be added to maintenance fluids once a patient has voided urine, usually at 20 mEq/L
    • In the first day of life you give D10W – used in newborns in the first 24 hours of life
      • They still have the electrolytes from the mother
    • D10 0.2 % normal saline – if continuing IVF on a newborn, used after the first 24h of life
    • 4:2:1 rule for maintenance fluid rate
      • First 10 kg – 4 mL/kg/hour
      • Next 10 kg – 2 mL/kg/hour
      • Additional kg – 1mL/kg/hour
    • Goal of urine output is 1-2 mL/kg/hr

Why children are at higher risk for dehydration?

  • High SA to volume ratio – increases volume lost via evaporation
  • High basal metabolic rate (high heart rate and RR relative to adults) – metabolism consumes water
  • Higher proportion of body weight that is water

Approach to GERD and Vomiting

  • General history
    • Pregnancy and birth history
      • Polyhydramnios (suggestive of duodenal atresia)
      • Prolonged labor / complicated labor e.g. shoulder dystocia
      • Premature or at term
      • Weight at term
      • Time between birth and breathing/crying
    • Dietary history
      • Formula
        • Standard formula
        • Specialty formula
          • Lactose free formula is associated with constipation
          • Partially or fully hydrolysed (also known as hypoallergenic) formula is not associated with constipation and is trialled in cases of suspected cow milk protein allergy (see later steps)
      • Breastfeeding
    • Immunizations
      • Up to date on immunizations?
    • Medications and drug allergies
    • Family history
      • Look for things like IBD, pyloric stenosis, CMPA, intussusception
  • Warning signals indicating to investigate for other causes
    • Bilious vomiting
    • Projectile vomiting
    • Abdominal pain or distention
    • Fever
    • Systemic Signs
    • Poor weight gain
    • Blood in stool or vomit
    • Irritability “unhappy baby”
  • If none, and mom just reports excessive spitting up but no other symptoms, can try thickening formula with rice cereal then reassess after 2 weeks
    • If symptoms don’t improve then move to next step
  • If symptoms in keeping with uncomplicated reflux can do trial of cow’s milk and soy free diet for 2 weeks and reassess
    • If symptoms improve then continue avoiding cow’s milk and soy free diet for child
    • Side note: want to avoid soy milk for infants because a) there is cross reactivity between cow’s milk protein and soy milk protein b) increased levels of estrogen in soy milk
  • If symptoms don’t improve after either avoiding cow and soy milk the do a trial of acid suppression (lansoprazole i.e. prevacid 2.5 mL typically) for 2 weeks
    • If symptoms improve then continue for 6-8 weeks and the do another trial off of the lansoprazole
  • If symptoms do not improve even after the acid suppression trial then it may be time to investigate for other causes
    • Try a fully hydrolyzed formula (amino acid based formula) such as Puramino
    • Referral to allergist
    • CBC, electrolytes, celiac screen
    • Upper GI series
    • Referral for paediatric gastroenterologist and upper endoscopy