What are the IV fluid (Intravenous Fluid) (IVF) bolus and maintenance rates for an 8-month-old child with moderate dehydration?

IV Fluid Management for 8-Month-Old with Moderate Dehydration

For this 18.4 kg, 8-month-old with moderate dehydration requiring admission, administer isotonic crystalloid boluses of 20 mL/kg (368 mL) over 1-2 hours until perfusion normalizes, followed by isotonic maintenance fluids at 76 mL/hour (1840 mL/day) using D5 0.9% NaCl or balanced crystalloid with dextrose. 1

Initial Resuscitation (Bolus Therapy)

• Administer 20 mL/kg of isotonic crystalloid (0.9% NaCl or lactated Ringer's) intravenously until pulse, perfusion, and mental status return to normal. 1 For this 18.4 kg child, this equals 368 mL per bolus.

• Reassess after each bolus and repeat 20 mL/kg boluses as needed until clinical signs of dehydration resolve (improved skin turgor, moist mucous membranes, normalized capillary refill, adequate urine output). 1, 2

• Monitor for signs of fluid overload during resuscitation, particularly if multiple boluses are required. 1

Maintenance Fluid Therapy

Once resuscitation is complete and the child is stabilized:

Volume Calculation

Using the Holliday-Segar formula for an 18.4 kg child: 1

• First 10 kg: 100 mL/kg/day = 1000 mL
• Next 8.4 kg: 50 mL/kg/day = 420 mL
• Total maintenance: 1420 mL/day = 59 mL/hour

However, recent guidelines recommend restricting maintenance volumes to 60-80% of traditional calculations in hospitalized children to prevent hyponatremia. 1 Therefore, use approximately 76 mL/hour (1840 mL/day at 80% of calculated maintenance).

Fluid Composition

• Use isotonic fluids (0.9% NaCl or balanced crystalloid like lactated Ringer's) with 5% dextrose. 1

• Avoid hypotonic fluids (0.45% NaCl or 0.2% NaCl), as they significantly increase the risk of hospital-acquired hyponatremia in acutely ill children. 1

• Add potassium chloride 20 mEq/L once urine output is established and serum potassium is known. 1, 3

• Balanced crystalloid solutions (e.g., lactated Ringer's, PlasmaLyte) are preferred over 0.9% NaCl to reduce risk of hyperchloremic acidosis. 1

Specific Fluid Recommendation

D5 0.9% NaCl with 20 mEq/L KCl at 76 mL/hour is the most appropriate maintenance fluid for this patient. 1, 3

Ongoing Loss Replacement

• Replace each diarrheal stool with 10 mL/kg (184 mL) of oral rehydration solution (ORS) if tolerated. 1, 2

• Replace each vomiting episode with 2 mL/kg (37 mL) of ORS if tolerated. 2

• If unable to tolerate oral replacement, add these volumes to the IV maintenance rate. 1

Additional Admitting Orders

Monitoring

• Check serum electrolytes (sodium, potassium, chloride, bicarbonate), glucose, and renal function (BUN, creatinine) at baseline and every 12-24 hours. 1

• Monitor vital signs every 4 hours, including heart rate, blood pressure, respiratory rate, and temperature. 1

• Strict intake and output monitoring, including documentation of all stool and emesis volumes. 1

• Daily weights at the same time each day to assess fluid balance. 2

Nutrition

• Continue breastfeeding on demand if breastfed, or resume full-strength formula immediately once rehydration is complete. 1, 2

• Do not dilute formula—this provides no benefit and may worsen nutritional status. 1

• Offer age-appropriate solid foods every 3-4 hours as tolerated. 1

Diagnostic Workup (if indicated)

• Stool culture, ova and parasites, and Clostridioides difficile testing if bloody diarrhea, high fever, recent antibiotic use, or diarrhea persisting >5 days. 1

• Consider rotavirus testing if not vaccinated and severe gastroenteritis. 1

Glucose Management

• Maintain blood glucose >60 mg/dL by ensuring all IV fluids contain 5% dextrose (D5). 1

• Check blood glucose if altered mental status, lethargy, or poor feeding develops. 1

Critical Pitfalls to Avoid

• Do not use hypotonic maintenance fluids (0.45% NaCl or 0.2% NaCl)—these dramatically increase the risk of life-threatening hyponatremia in hospitalized children. 1 Acutely ill children have elevated antidiuretic hormone (ADH) secretion, impairing free water excretion. 1

• Do not calculate maintenance fluids based on full Holliday-Segar volumes—restrict to 60-80% to prevent fluid overload and hyponatremia. 1

• Do not add potassium to IV fluids until urine output is documented and hyperkalemia is excluded. 1, 3

• Do not delay rehydration while awaiting laboratory results—begin isotonic boluses immediately based on clinical assessment. 1, 2

• Do not use plain 0.9% NaCl without dextrose for maintenance—this risks hypoglycemia in infants. 1

• Do not overlook ongoing losses—failure to replace continued diarrheal losses will result in persistent dehydration despite adequate initial resuscitation. 1, 2

• Monitor for signs of hyponatremia (lethargy, confusion, seizures) and hypernatremia (irritability, altered mental status), as both can cause serious neurologic complications. 1