What are the guidelines for choosing IV fluids in pediatric patients with dehydration?

How to Decide on IV Fluids in Pediatric Patients

Initial Assessment: Determine Severity of Dehydration

First, clinically assess the degree of dehydration by examining skin turgor (pinch test with >2 seconds return indicates severe), capillary refill time, mucous membrane moisture, mental status, and perfusion—categorizing as mild (3-5% fluid deficit), moderate (6-9% fluid deficit), or severe (≥10% fluid deficit). 1, 2

Key physical findings to prioritize:

• Severe dehydration indicators: Altered consciousness, prolonged skin tenting >2 seconds, cool/poorly perfused extremities, rapid deep breathing (acidosis) 1
• Moderate dehydration: Decreased skin turgor, dry mucous membranes, sunken eyes 1
• Mild dehydration: Slightly decreased skin turgor, normal mental status 1

Weigh the patient immediately—this is essential for calculating fluid volumes and monitoring treatment effectiveness 1, 2

---

Decision Algorithm: IV vs Oral Rehydration

For Severe Dehydration (≥10% deficit)

Immediately initiate IV rehydration with isotonic crystalloid (0.9% NaCl or lactated Ringer's) at 20 mL/kg boluses—this is a medical emergency requiring rapid restoration of circulation. 1, 2, 3

• Administer repeated 20 mL/kg boluses until pulse, perfusion, and mental status normalize 1, 2
• May require two IV lines or alternate access (venous cutdown, femoral vein, intraosseous) 1
• Once consciousness returns, transition to oral rehydration for remaining deficit 3, 4

For Mild-to-Moderate Dehydration (3-9% deficit)

Oral rehydration solution (ORS) containing 50-90 mEq/L sodium is first-line therapy and equally effective as IV fluids, with faster initiation time and lower cost. 3, 5, 6

• Administer 50 mL/kg ORS over 2-4 hours for mild dehydration 1, 3
• Administer 100 mL/kg ORS over 2-4 hours for moderate dehydration 1, 3
• Consider nasogastric administration if oral intake fails 4, 5

Use IV fluids for mild-to-moderate dehydration only when oral/nasogastric routes fail due to intractable vomiting or altered mental status. 5, 6

---

IV Fluid Selection: Composition Matters

For Resuscitation (Severe Dehydration)

Use isotonic crystalloid without dextrose: 0.9% NaCl or lactated Ringer's solution for initial boluses. 1, 2, 3

For Maintenance Therapy (After Resuscitation)

Use isotonic balanced solutions with 5% dextrose (e.g., 0.9% NaCl + 5% dextrose or Plasmalyte + 5% glucose)—hypotonic fluids dramatically increase the risk of life-threatening iatrogenic hyponatremia. 1, 2, 7

Key composition requirements:

• Sodium concentration: 130-154 mEq/L (isotonic) 1
• Glucose: 4-10% for children, 5% minimum to prevent hypoglycemia 1, 2
• Potassium: Add 20 mEq/L once urine output established and hyperkalemia excluded 1, 2
• Balanced solutions preferred: Use lactated Ringer's or Plasmalyte over plain saline to avoid hyperchloremic acidosis 1

Critical pitfall: Never use hypotonic solutions (0.45% NaCl or 0.2% NaCl) for maintenance—multiple RCTs demonstrate significantly increased hyponatremia risk without benefit. 1, 2, 7

---

IV Fluid Volume Calculation

Maintenance Volume

Calculate using Holliday-Segar formula, but restrict to 60-80% of calculated maintenance to prevent hyponatremia and fluid overload in acutely ill children. 1, 2

Holliday-Segar calculation:

• 100 mL/kg/day for first 10 kg
• 50 mL/kg/day for next 10 kg
• 20 mL/kg/day for each kg above 20 kg 1, 2

Example: For an 18.4 kg child, full maintenance = 1420 mL/day, but administer only 60-80% = 850-1136 mL/day (35-47 mL/hour) 2

Ongoing Loss Replacement

Replace each diarrheal stool with 10 mL/kg of ORS or IV fluid. 1, 2, 4

Replace each vomiting episode with 2 mL/kg of ORS or IV fluid. 1, 2

For measurable ileostomy output: 1 mL fluid per 1 gram of output 1, 4

---

Monitoring Requirements

Check serum electrolytes (sodium, potassium, chloride, bicarbonate), glucose, BUN, and creatinine at baseline and every 12-24 hours during IV therapy. 2

• Reassess hydration status after 2-4 hours of therapy 1, 3
• Monitor vital signs every 4 hours 2
• Watch for fluid overload signs, especially after multiple boluses 2

Common pitfall: Routine laboratory testing is unnecessary for uncomplicated mild-to-moderate dehydration treated with oral rehydration—reserve for severe cases or when clinical concern exists for electrolyte abnormalities. 1, 5

---

Transition to Enteral Nutrition

Resume full-strength feeding immediately once rehydration achieved—do not delay nutrition. 1, 2, 3

• Continue breastfeeding on demand throughout rehydration 1, 3
• Use full-strength formula (not diluted) for bottle-fed infants 1, 3
• Resume age-appropriate diet for older children 3

Avoid antimotility drugs (loperamide) in children <18 years—they provide no benefit and carry risk. 3

---

Special Considerations

Neonates and Infants

Neonates require higher glucose concentrations (5-10%) and careful sodium/potassium monitoring from day 1 of life when receiving adequate amino acids and energy. 1

Dehydrated Patients Requiring Hyperoncotic Albumin

If patient is dehydrated, albumin 25% will worsen dehydration by pulling interstitial fluid—use crystalloids first or switch to albumin 5%. 8

Rapid IV Rehydration Protocol

For moderate dehydration when IV chosen, 0.9% saline + 2.5% dextrose at 20 mL/kg/hour for 2 hours is safe and effective. 9

This approach improves clinical scores faster than traditional slower rates while maintaining safety 9