Estimate % fluid deficit from clinical signs and weight loss. Mild (3–5%), moderate (6–9%), severe (≥10%). Oral rehydration is first-line for mild–moderate; IV resuscitation for severe or failed ORT.
🚩 Red-flag clues (must not miss)
- •Severe (≥10%): mottled skin, weak pulses, anuria, deep rapid breathing — shock
- •Hypernatremic dehydration (Na > 150) — doughy skin, deceptively preserved circulation; correct slowly to avoid cerebral edema
- •Hyponatremic dehydration (Na < 130) with seizure — give 3% saline 3–5 mL/kg
Exam
- Best single sign: prolonged cap refill > 2 s
- Weight loss is gold standard if recent baseline known
- Sunken fontanelle (infant), absent tears, dry mucous membranes, lethargy
Labs
- Mild: none
- Moderate–severe or persistent vomiting: BMP, glucose, VBG, urine SG
- Hypernatremic / hyponatremic dehydration → recheck Na q2–4h
Differential & next step
| Diagnosis | Clue | Next step |
|---|---|---|
| Isonatremic (most common) | Na 135–145 | NS 20 mL/kg bolus; deficit + maintenance over 24 h |
| Hypernatremic | Na > 150, doughy skin | Correct over 48–72 h; ↓ Na ≤ 0.5 mEq/L/h to avoid cerebral edema |
| Hyponatremic | Na < 130, seizure risk | If seizing: 3% NS 3–5 mL/kg over 10–15 min |
Medications & dosing
| Drug | Dose | Notes |
|---|---|---|
| 0.9% NaCl bolus | 20 mL/kg IV over 10–20 min, repeat ×2 (60 mL/kg) PRN | Reassess after each bolus; consider sepsis/cardiac if no response |
| Maintenance fluid (Holliday–Segar) | 4 mL/kg/h for first 10 kg + 2 for next 10 + 1 for each kg > 20 | Use isotonic fluid (D5NS or D5LR) to avoid hospital-acquired hyponatremia |
| Ondansetron PO | 0.15 mg/kg (max 8 mg) ×1 to facilitate ORT | |
| 3% NaCl (severe symptomatic hyponatremia) | 3–5 mL/kg IV over 10–15 min |
Management / next steps
- Mild (3–5%): ORT 50 mL/kg over 4 h + replace ongoing losses
- Moderate (6–9%): ORT 100 mL/kg over 4 h, anti-emetic, observe
- Severe (≥ 10%): NS bolus, admit, monitor electrolytes, hourly UO
Source: https://fprmed.com/fprmedcom/Pages/Pedi/Dehydration_pedi.html
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