What is the treatment for isotonic dehydration in pediatric patients?

Treatment of Isotonic Dehydration in Pediatric Patients

For mild to moderate isotonic dehydration, administer reduced osmolarity oral rehydration solution (ORS) at 50 mL/kg over 2-4 hours for mild dehydration or 100 mL/kg over 2-4 hours for moderate dehydration; for severe dehydration, use isotonic intravenous fluids (lactated Ringer's or normal saline) at 20 mL/kg boluses until circulation normalizes, then transition to ORS. 1, 2, 3

Assessment of Dehydration Severity

Before initiating treatment, determine the degree of dehydration through physical examination findings 3:

• Mild dehydration (3-5% fluid deficit): Increased thirst, slightly dry mucous membranes 3
• Moderate dehydration (6-9% fluid deficit): Loss of skin turgor, dry mucous membranes, decreased urine output, rapid deep breathing, prolonged skin retraction time 4, 3
• Severe dehydration (≥10% fluid deficit): Severe lethargy or altered consciousness, prolonged skin tenting, abnormal capillary refill time, decreased perfusion 3

Weighing the child establishes a baseline for monitoring treatment effectiveness 2

Treatment Algorithm by Severity

Mild to Moderate Dehydration (First-Line: Oral Rehydration)

Use reduced osmolarity ORS containing 50-90 mEq/L sodium as first-line therapy 1, 4, 3:

• Mild dehydration: Administer 50 mL/kg ORS over 2-4 hours 3
• Moderate dehydration: Administer 100 mL/kg ORS over 2-4 hours 2, 4

Start with small volumes (one teaspoon) using a teaspoon, syringe, or medicine dropper, then gradually increase as tolerated 4. Reassess hydration status after 2-4 hours; if still dehydrated, reestimate the fluid deficit and restart rehydration 4

If oral intake is not tolerated, consider nasogastric administration of ORS in children with normal mental status who are too weak or refuse to drink adequately 1, 2

Severe Dehydration (Immediate IV Rehydration Required)

Administer isotonic intravenous fluids immediately - this is a medical emergency 3:

• Use lactated Ringer's solution or normal saline (0.9% saline) as first-line IV fluid 1, 2
• Give boluses of 20 mL/kg over the first 2-4 hours until pulse, perfusion, and mental status normalize 2, 5
• Continue IV rehydration until the child awakens, has no risk factors for aspiration, and shows no evidence of ileus 1, 2

Once circulation is restored and the patient is alert, transition to ORS for the remaining fluid deficit 1, 2, 5

Replacement of Ongoing Losses

During both rehydration and maintenance phases, replace ongoing losses 2, 4:

• Administer 10 mL/kg ORS for each diarrheal stool 4
• Administer 2 mL/kg ORS for each episode of emesis 4
• For measurable ileostomy losses, give 1 mL ORS for each gram of output 2

Continue ORS replacement until diarrhea and vomiting resolve 1

Maintenance and Feeding

Resume feeding as soon as rehydration is achieved 1, 3:

• Breastfed infants: Continue nursing on demand throughout the illness 1, 4, 3
• Bottle-fed infants: Use full-strength, lactose-free, or lactose-reduced formulas immediately upon rehydration 4, 3
• All children: Resume age-appropriate usual diet during or immediately after rehydration is completed 1, 3

Avoid "resting the bowel" through fasting 3

Critical Pitfalls to Avoid

Do not use hypotonic solutions for initial rehydration in severe dehydration, as they may worsen electrolyte imbalances 2. In isotonic dehydration specifically, the sodium and water losses are proportional, making isotonic crystalloid solutions (0.9% saline or lactated Ringer's) the appropriate choice for IV rehydration 6, 5

Avoid popular beverages like apple juice, Gatorade, and commercial soft drinks for rehydration, as they have inappropriate osmolality and electrolyte composition 2, 3

Do not give antimotility drugs (e.g., loperamide) to children <18 years of age with acute diarrhea 1

Do not delay transition to oral rehydration once the child is alert and able to drink 2

When to Switch from Oral to IV Therapy

Indications for IV fluid therapy include 1, 4:

• Severe dehydration, shock, or altered mental status
• Failure of ORS therapy
• Ileus
• Progression to severe dehydration despite oral rehydration
• Inability to tolerate oral or nasogastric intake

Children with serum bicarbonate ≤13 mEq/L are more likely to require hospitalization and continued IV therapy 7