Intravenous Fluid of Choice for Pediatric Acute Gastroenteritis
For children with acute gastroenteritis requiring intravenous fluids, use isotonic balanced crystalloid solutions (such as Plasmalyte or lactated Ringer's) with glucose (4-10%) and potassium (~4 mmol/L), avoiding hypotonic solutions entirely. 1, 2
Initial Consideration: Is IV Therapy Actually Needed?
- Oral rehydration therapy (ORT) should be attempted first for mild to moderate dehydration, as it is equally effective as IV therapy and reduces costs and complications 1, 3, 4
- Reserve IV fluids for severe dehydration (>6% body weight loss), shock, altered mental status, or failure of oral rehydration 3, 4
- Signs requiring IV therapy include: decreased skin turgor, sunken eyes, dry mucous membranes, tachycardia, decreased urine output, or inability to tolerate oral intake 3, 4
Specific IV Fluid Composition
Tonicity: Isotonic Solutions Only
- Use isotonic fluids (sodium 135-144 mEq/L) exclusively to prevent hospital-acquired hyponatremia, which occurs in 18.5% of children receiving hypotonic fluids 1, 5
- Gastroenteritis causes excess arginine vasopressin (AVP) secretion from volume depletion, nausea, and vomiting—making hypotonic fluids particularly dangerous as free water will be retained 5
- Recent evidence confirms isotonic solutions do not cause hypernatremia in infants, while hypotonic solutions led to acquired hyponatremia in 8.5% of cases 6
Solution Type: Balanced Over Normal Saline
- Balanced crystalloid solutions (Plasmalyte, lactated Ringer's) should be preferred over 0.9% normal saline as they reduce length of stay (Level A evidence for acute illness, Level B for critical illness) 1, 2
- Avoid lactate-buffered solutions only in severe liver dysfunction to prevent lactic acidosis 1
Essential Additives
- Add glucose 4-10% to prevent hypoglycemia, with daily blood glucose monitoring required 1, 2
- Add potassium (~4 mmol/L) based on clinical status and regular monitoring to prevent hypokalemia 1, 2
- Routine supplementation of calcium, magnesium, phosphate, vitamins, or trace elements is not recommended unless deficiency signs are present 1
Initial Resuscitation Protocol
- For severe dehydration: administer 20 mL/kg boluses of isotonic fluid (lactated Ringer's or normal saline) over 30 minutes 3, 4
- Continue boluses until pulse, perfusion, and mental status normalize, typically over 2-4 hours 4
- After initial resuscitation, transition to isotonic balanced solution with glucose and potassium for maintenance 1
Volume and Rate Considerations
Standard Rehydration Rate
- Standard volume IV rehydration at 20 mL/kg/h for 1-4 hours is sufficient for most children with gastroenteritis 7
- Rapid high-volume rehydration (60 mL/kg/h) shows no superiority and may increase time-to-discharge and readmission rates 7
Maintenance Fluid Calculations
- Calculate total daily maintenance including ALL sources: IV fluids, blood products, medications, line flushes, and enteral intake (excluding replacement fluids) 1, 2
- For children at risk of increased ADH secretion (which includes gastroenteritis), restrict maintenance to 65-80% of Holliday-Segar formula to prevent fluid overload and hyponatremia 1, 2
- Reassess fluid balance, clinical status, and sodium levels at least daily 1, 2
Critical Pitfalls to Avoid
- Never use hypotonic solutions (0.45% or 0.2% NaCl) for gastroenteritis—this outdated practice causes preventable hyponatremia and has resulted in deaths from hyponatremic encephalopathy 5
- Avoid "fluid creep" by accounting for all fluid sources, not just maintenance bags 1, 2
- Do not use adult formulations lacking glucose, as children require glucose to prevent hypoglycemia 1
- Avoid excessive fluid administration leading to positive fluid balance, which prolongs mechanical ventilation and hospital stay 1, 2
Transition to Oral Intake
- Resume oral rehydration and age-appropriate diet as soon as tolerated, typically after initial resuscitation 3, 4
- Continue breastfeeding throughout the illness 3, 4
- Replace ongoing losses with ORS: 60-120 mL per diarrheal stool for children <10 kg, 120-240 mL for children >10 kg 4