What is the best maintenance fluid for a gastroenteritis patient with dehydration?

Best Maintenance Fluid for Gastroenteritis Patients with Dehydration

Oral rehydration solution (ORS) is the best maintenance fluid for gastroenteritis patients with dehydration, with isotonic intravenous fluids (lactated Ringer's or normal saline) reserved for cases of severe dehydration. 1

Assessment of Dehydration

Before selecting the appropriate fluid, assess the degree of dehydration:

• Mild dehydration (3-5%): Increased thirst, slightly dry mucous membranes
• Moderate dehydration (6-9%): Loss of skin turgor, dry mucous membranes
• Severe dehydration (≥10%): Severe lethargy, altered consciousness 1

Fluid Selection Algorithm

1. Mild to Moderate Dehydration

• First-line treatment: Oral rehydration therapy (ORT) with ORS
• Optimal ORS composition:
  • Sodium: 65-70 mEq/L
  • Glucose: 75-90 mmol/L
  • Potassium: 20 mEq/L
  • Chloride: 65-80 mEq/L
  • Citrate: 10 mEq/L 1

2. Severe Dehydration

• Initial treatment: Isotonic intravenous fluids (lactated Ringer's or normal saline)
• Transition: Switch to ORS when the patient stabilizes 1

Administration Guidelines

For Mild Dehydration:

• Administer 50 mL/kg of ORS over 2-4 hours 1

For Moderate Dehydration:

• Administer 100 mL/kg of ORS over 2-4 hours 1

For Severe Dehydration:

• Calculate maintenance fluids using the Holliday-Segar method:
  • First 10 kg: 100 mL/kg/day
  • Second 10 kg: 50 mL/kg/day
  • Each additional kg: 20 mL/kg/day 1

Ongoing Maintenance:

• After rehydration, replace ongoing losses with ORS:
  • 10 mL/kg of ORS after each loose stool
  • 2 mL/kg after each episode of vomiting 1

Important Considerations

• Low-osmolality ORS is preferred as it helps effectively absorb water and electrolytes regardless of the cause of gastroenteritis 2
• Evaluate hydration status every 2-4 hours and monitor weight daily 1
• Continue breastfeeding throughout the diarrheal episode if applicable 1
• Resume age-appropriate diet during or immediately after rehydration 1

Common Pitfalls to Avoid

• Do not use inappropriate fluids such as sports drinks, juices, or sodas, which have improper electrolyte compositions and can worsen dehydration 1
• Avoid allowing dehydrated patients to drink large volumes of ORS at once 1
• Do not use antimotility medications in children under 18 years due to risk of serious adverse events 1
• Do not restrict food, as early refeeding decreases intestinal permeability and improves outcomes 1

Special Situations

• For oral intolerance: Consider ondansetron for children over 4 years to facilitate ORS tolerance when vomiting is present 1
• For nasogastric administration: ORS can be administered via nasogastric tube in selected cases of oral intolerance 2

The evidence strongly supports ORS as the cornerstone of treatment for gastroenteritis with dehydration, with the World Health Organization's low-osmolality formulation showing the best efficacy profile for both prevention and treatment of dehydration 1, 2.