A 18-month-old boy from rural Maharashtra presents to the emergency department with a 3-day history of watery diarrhea and vomiting. His mother reports he has passed 8–10 loose stools per day for the past 2 days. On examination, he appears lethargic, his anterior fontanelle is sunken, skin turgor is decreased (skin pinch goes back in >2 seconds), and mucous membranes are dry. Capillary refill time is 2.5 seconds. His weight is 11 kg (baseline 12 kg). Serum sodium is 128 mEq/L, potassium 3.2 mEq/L, chloride 98 mEq/L, and HCO₃⁻ is 12 mEq/L. What is the most appropriate immediate management?

Explanation

## Clinical Assessment **Degree of Dehydration:** - Weight loss: (12 − 11)/12 = 8.3% (moderate dehydration) - Sunken fontanelle, decreased skin turgor (>2 sec), dry mucous membranes, lethargy, delayed capillary refill (2.5 sec) = **severe dehydration signs** - Hyponatremia (128 mEq/L) with hypokalemia (3.2 mEq/L) and metabolic acidosis (HCO₃⁻ 12) indicate significant electrolyte loss ## Why IV Bolus is Indicated Here **Key Point:** The presence of **lethargy, sunken fontanelle, and delayed capillary refill (≥2 sec)** indicates hypovolemic shock or impending shock — oral rehydration alone is insufficient and unsafe. **High-Yield:** WHO/UNICEF guidelines (2005, reaffirmed in 2023) recommend: - **Severe dehydration with signs of shock** → IV rehydration - **Moderate dehydration without shock** → ORS (can use IV if unable to tolerate orally) - **Mild dehydration** → ORS ## Correct Management Algorithm ```mermaid flowchart TD A["Acute diarrhea + dehydration"]:::outcome --> B{"Clinical signs of shock?"}:::decision B -->|"Lethargy, sunken fontanelle,<br/>cap refill ≥2 sec, weak pulse"| C["IV bolus: 0.9% NS<br/>20 mL/kg over 15 min"]:::action B -->|"Moderate dehydration,<br/>alert, normal perfusion"| D["ORS 75 mmol/L<br/>50-100 mL/kg over 4 hrs"]:::action C --> E{"Reassess after bolus"}:::decision E -->|"Improved perfusion"| F["Switch to ORS or IV maintenance"]:::action E -->|"Persistent shock"| G["Repeat bolus + investigate<br/>for sepsis/other cause"]:::urgent D --> H["Monitor, continue ORS"]:::action ``` ## Fluid Choice Rationale | Fluid | Indication | Why NOT here | |-------|-----------|---------------| | **0.9% NaCl bolus** | Hypovolemic shock, severe dehydration | **CORRECT** — restores circulating volume rapidly | | Hypotonic (0.45% NS) | Maintenance only, NOT for bolus | Risk of cerebral edema in acute phase | | 5% dextrose | Maintenance, not dehydration | Hypotonic; worsens hyponatremia | | 3% hypertonic saline | Symptomatic hyponatremia (seizures) | This child has asymptomatic hyponatremia; hypertonic saline risks osmotic demyelination | **Clinical Pearl:** Hyponatremia (128 mEq/L) in acute diarrhea is **dilutional** (from free water retention and loss of Na⁺-rich stool). Rapid correction with hypertonic saline is **contraindicated** — correct slowly over 48 hours as dehydration is corrected. ## Post-Bolus Management 1. Reassess perfusion, urine output, and mental status after 15 minutes 2. If improved: switch to ORS (75 mmol/L) or IV maintenance + replacement 3. If shock persists: repeat bolus, investigate for sepsis (blood culture, lactate) 4. Monitor electrolytes, especially K⁺ (give 20 mEq/L KCl in maintenance fluids once urine output confirmed) **High-Yield:** The **75 mmol/L ORS** (WHO formulation: 75 mmol/L Na⁺, 65 mmol/L Cl⁻, 20 mmol/L K⁺, 10 mmol/L glucose) is superior to older 90 mmol/L solutions — it reduces stool output by ~20% and hypernatremia risk.