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Management of Dehydration in Pediatrics

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1. Pathophysiology Overview

• They depend on caregivers for fluid intake
• Total body water is ~70% of body weight at birth (vs. ~60% in older children)
• Higher surface-area-to-body-mass ratio → greater insensible losses
• Immature renal concentrating ability
• Higher metabolic rates (peak at 12 months); fever raises BMR by 13% per °C above 37.8°C

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2. Classification

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3. Clinical Assessment

Degrees of Dehydration (AAP/ESPGHAN Framework)

Single signs have poor predictive value; use combinations. Prolonged capillary refill, abnormal skin turgor, and abnormal respiratory pattern are the best clinical predictors of >5% dehydration.

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4. Laboratory Testing

• No dehydration / mild: No labs required
• Moderate: Optional (based on history/disease state)
• Severe, IV rehydration needed: Electrolytes, BUN, creatinine, calcium, glucose, urinalysis
• AAP recommendation: Electrolyte testing for severe dehydration, those needing IV therapy, or moderate dehydration with concerning features

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5. Treatment by Severity

5a. Mild Dehydration — Oral Rehydration Therapy (ORT)

• Use WHO reduced-osmolarity ORS (sodium 75 mEq/L, glucose 75 mmol/L, osmolarity 245 mOsm/L), or commercial solutions (Pedialyte, Enfalyte)
• Dilute apple juice or patient-preferred fluid is an acceptable alternative in mild cases
• Administer 5 mL (1 tsp) every 2–3 minutes, increasing based on tolerance
• Target: 50–100 mL/kg for the rehydration phase
• Replace ongoing losses: 10 mL/kg per diarrheal stool, 2 mL/kg per emesis episode
• If vomiting: ondansetron (oral) may facilitate tolerance of ORT

5b. Moderate Dehydration — ORT first, escalate if needed

• Attempt ORT as above
• If ORT fails → Nasogastric (NG) rehydration: ORS at 10–20 mL/kg/h
  • NG hydration is as effective as IV even in vomiting children; fewer complications and more cost-effective
• IV alternative: 20 mL/kg 0.9% NS over 1 hour, then reassess

Note: Rapid/ultrarapid IV hydration (50–60 mL/kg in 1 hour) shows no advantage over standard rehydration for moderate dehydration and was associated with increased hospitalization rates in an RCT.

5c. Severe Dehydration — IV / IO Resuscitation

• Up to 60–100 mL/kg may be required in the first hour
• Use 0.9% saline or Lactated Ringer's during resuscitation phase
• After stabilization: continue with NS or 5% dextrose in 0.9% NS
• IO access if IV unobtainable
• If IV access fails in severe cases: IO line (placed avg. 46 seconds faster than umbilical lines in neonates)

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6. Maintenance Fluids (Holliday-Segar Formula)

• 10 kg infant: 1000 mL/day
• 20 kg child: 1500 mL/day
• 40 kg child: 1900 mL/day

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7. Special Electrolyte Considerations

Hypernatremic Dehydration (Na >145 mEq/L)

• Correct serum sodium no faster than 1 mEq/L/hour, no more than 15 mEq/L in first 24 hours
• Rapid correction risks cerebral edema and central pontine myelinolysis
• May take >48 hours for full correction
• Dialysis if Na >180 mmol/L or volume overload prevents correction

Hyponatremia

• Evaluate for SIADH, GI losses, or excessive free water intake
• If symptomatic (seizures): hypertonic saline to raise Na by 3–5 mEq/L acutely; then gradual correction

Hypokalemia (K <3.4 mEq/L)

• Common with vomiting/diarrhea or DKA
• Oral: 2–5 mEq/kg/day in divided doses (max 40 mEq/dose)
• IV: 0.2–0.3 mEq/kg/h; up to 0.5 mEq/kg/h for cardiac/respiratory urgency with continuous ECG monitoring

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8. Discharge Criteria

• Clinically well, alert, and oriented
• Vital signs within normal limits for age
• Adequate urine output during hydrating period
• Intake ≥ ongoing losses

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9. Route Summary Table

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Pediatric DKA — Viva Q&A

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Q1. What is DKA? Define it.

1. Hyperglycemia (glucose typically >250 mg/dL)
2. Metabolic acidosis with elevated anion gap (bicarbonate <15 mEq/L, pH <7.3)
3. Ketonemia / ketonuria

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Q2. What are the diagnostic criteria for DKA in children?

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Q3. What are the typical deficits in pediatric DKA?

Key concept: Despite total-body K⁺ deficit, serum K⁺ may be normal or high on presentation due to acidosis-driven K⁺ shift out of cells.

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Q4. What investigations do you do?

• Blood glucose (bedside)
• Venous blood gas (pH, HCO₃⁻, pCO₂)
• Serum electrolytes (Na, K, Cl, HCO₃⁻)
• BUN, creatinine
• Urine ketones / dipstick
• ECG (rapid K⁺ assessment if labs delayed)

• Anion Gap = Na − (Cl + HCO₃⁻) → normal 8–12; raised in DKA
• Corrected sodium = Measured Na + 1.6 × [(glucose − 100)/100]
• Effective osmolality = 2 × Na + glucose/18 (normal <340 mOsm/L)

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Q5. What is the management of DKA in children? (Step by step)

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STEP 1 — ABC, Monitoring & IV Access

• Secure IV access immediately
• Cardiac monitoring (K⁺ changes)
• Monitor glucose hourly, electrolytes every 2 hours
• Input/output chart — target urine output 1–2 mL/kg/h
• Avoid intubation if possible (difficult to match the child's compensatory hyperventilation; intubation risks worsening acidosis)

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STEP 2 — Fluid Resuscitation

• 20 mL/kg 0.9% normal saline IV over 1 hour, repeat if still hypotensive
• Repeat until hemodynamically stable

• Deficit = 5–10% of body weight (e.g., 10 kg child with 10% dehydration = 1000 mL deficit)
• Replace deficit evenly over 24–48 hours
• Traditional approach: 50% of deficit in first 8 hours, remainder over next 16–24 hours
• Add maintenance fluids on top
• Run NS (0.9%) or 0.45%–0.9% NaCl at 1.5× maintenance rate

Why not rapid correction? Risk of cerebral edema, especially if osmolality >340 mOsm/L. Ensure serum sodium rises as glucose falls — failure of Na to rise is an early warning sign of cerebral edema.

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STEP 3 — Potassium Replacement

Key rule: Never give insulin when K⁺ <3.0 mEq/L — insulin drives K⁺ intracellularly and can precipitate fatal arrhythmia.

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STEP 4 — Insulin Therapy

• Do NOT give an IV insulin bolus (no longer recommended)
• Start insulin only after fluid bolus is complete
• Regular insulin infusion: 0.1 unit/kg/hour IV
• Target glucose decline: 50–100 mg/dL/hour
• Do NOT reduce insulin below 0.05 unit/kg/h — insulin is needed to clear ketosis even after glucose normalizes
• When glucose drops to 200–250 mg/dL, add dextrose (5–10%) to IV fluids — do NOT stop insulin
• Switch to subcutaneous insulin only when:
  • pH >7.3 AND HCO₃⁻ >15 mEq/L
  • Child tolerating oral intake
  • Ketones clearing

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STEP 5 — Bicarbonate?

• Worsens hypokalemia
• Delays ketosis clearance
• Causes paradoxical CSF acidosis
• No improvement in outcomes

Only consider if pH <6.9 with cardiovascular compromise (rare, and with caution).

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STEP 6 — Phosphate?

• Total-body phosphate depleted, but routine replacement not recommended unless severe hypophosphatemia (<1.0 mg/dL) or symptomatic (weakness, hemolysis)
• If replacing K⁺, using potassium phosphate as one of the two K⁺ salts simultaneously replaces phosphate

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Q6. What is the most feared complication of pediatric DKA?

Cerebral Edema

• Age <5 years
• Severe acidosis (low pH, low HCO₃⁻)
• Severe hyperosmolality (>340 mOsm/L)
• Failure of serum Na to rise as glucose falls
• Severe dehydration and hypocapnia prior to treatment
• Bicarbonate use

• Severe headache
• Declining mental status
• Seizures
• Papilledema
• Respiratory arrest may be the first sign

1. Mannitol 0.25–1 g/kg IV bolus — OR — Hypertonic saline 3%: 5–10 mL/kg over 30 minutes
2. Restrict further fluids to minimum
3. Endotracheal intubation if airway compromised (maintain hyperventilation to compensate for metabolic acidosis)
4. Transfer to PICU

• Avoid high-dose insulin
• Avoid sodium bicarbonate
• Gradual rehydration
• Monitor Na trend — it must rise

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Q7. What are other complications of DKA management?

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Q8. When can you switch to subcutaneous insulin?

• pH >7.3 AND HCO₃⁻ >15 mEq/L
• Anion gap closing (normalizing)
• Child alert, tolerating oral fluids
• Ketones resolving
• Give first SC dose 30–60 minutes before stopping insulin infusion (to avoid gap in coverage)

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Q9. Disposition — who gets admitted to PICU?

• Severe DKA (pH <7.1)
• Cerebral edema or altered consciousness
• Age <2 years
• Osmolality >340 mOsm/L
• Refractory electrolyte abnormalities

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Q10. Key numbers to remember for the viva

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