A 14-month-old boy from rural Maharashtra presents with a 3-day history of watery diarrhea (8–10 stools per day) and vomiting. On examination, he appears lethargic, with sunken eyes, loss of skin turgor (skin pinch goes back in >2 seconds), and a weak, thready pulse of 140/min. Capillary refill time is 3 seconds. His weight is 9 kg (baseline 10 kg). Serum sodium is 128 mEq/L, potassium 3.2 mEq/L, and bicarbonate 12 mEq/L. What is the most appropriate immediate management?

Explanation

## Clinical Assessment This child has **severe dehydration with hypovolemic shock** (lethargy, sunken eyes, skin turgor >2 seconds, weak pulse, prolonged capillary refill, 10% weight loss). The presence of **hyponatremia (128 mEq/L)** and **metabolic acidosis (HCO~3~⁻ 12 mEq/L)** confirms significant fluid and electrolyte loss. **Key Point:** Shock takes priority over electrolyte abnormalities in acute management. The child is in compensated hypovolemic shock and requires urgent fluid resuscitation. ## Immediate Management Algorithm ```mermaid flowchart TD A[Severe dehydration + shock signs]:::outcome --> B{Perfusion adequate?}:::decision B -->|No: weak pulse, prolonged CRT| C[IV bolus 0.9% saline]:::action B -->|Yes| D[Reassess after bolus]:::decision C --> E[100 mL/kg over 30 min]:::action E --> F[Reassess perfusion, urine output]:::decision F -->|Improved| G[Switch to maintenance + deficit]:::action F -->|No improvement| H[Repeat bolus, consider sepsis]:::urgent G --> I[Add K+ only after urine output]:::action ``` **High-Yield:** In **hypovolemic shock from diarrhea**, the first bolus is **isotonic saline (0.9%)** — NOT hypotonic fluids. The goal is to restore circulating volume and perfusion pressure, not to correct electrolytes immediately. ## Why This Approach 1. **Hyponatremia is secondary to hypovolemia** — correcting volume first allows renal perfusion and sodium excretion to normalize osmolality gradually. 2. **Potassium is contraindicated initially** — the child is oliguric (no urine output mentioned), and hyperkalemia risk is high. K⁺ is added only after urine output is documented. 3. **0.9% saline is isotonic** — it expands intravascular space without worsening hyponatremia acutely (the sodium concentration is 154 mEq/L, which is hypertonic relative to serum, but the large volume restores perfusion). 4. **Bolus dose: 100 mL/kg over 30 minutes** is standard for shock; repeat if perfusion does not improve. **Clinical Pearl:** The combination of lethargy + weak pulse + prolonged CRT + metabolic acidosis signals **compensated shock**. Waiting for ORS or slow IV infusion risks progression to decompensated shock and multi-organ failure. **Mnemonic: SHOCK in Diarrhea = Start with Saline, Hold K⁺, Observe perfusion, Check urine, Know when to repeat** [cite:Park 26e Ch 9]