What is the initial rate for starting maintenance intravenous (IV) fluids?

Initial Rate for Maintenance Intravenous Fluids

For children (28 days to 18 years), start maintenance IV fluids using the Holliday-Segar formula: 4 mL/kg/hr for the first 10 kg, plus 2 mL/kg/hr for the next 10 kg, plus 1 mL/kg/hr for each kg above 20 kg. 1, 2

For adults, start at approximately 25-30 mL/kg/day (roughly 1-1.25 mL/kg/hr), which translates to about 75-100 mL/hr for a typical 70 kg adult. 1, 3

Pediatric Maintenance Fluid Rates

The standard calculation for children follows this stepwise approach: 1, 2

• First 10 kg of body weight: 4 mL/kg/hr (or 100 mL/kg/day)
• Second 10 kg of body weight: Add 2 mL/kg/hr (or 50 mL/kg/day)
• Each kg above 20 kg: Add 1 mL/kg/hr (or 20 mL/kg/day)

Example: A 25 kg child would receive: (10 kg × 4) + (10 kg × 2) + (5 kg × 1) = 65 mL/hr 2

Fluid Composition for Children

Use isotonic balanced solutions with dextrose (D5 Lactated Ringer's or D5 0.9% NaCl) as first-line maintenance fluids in children. 1, 2 The American Academy of Pediatrics strongly recommends isotonic fluids to prevent hospital-acquired hyponatremia, which has been associated with deaths and serious neurological injury when hypotonic fluids were used. 1

D5 Lactated Ringer's is preferred because: 2

• Sodium concentration of 130 mEq/L (near-physiologic range of 135-145 mEq/L)
• Contains lactate buffer (28 mEq/L) and lower chloride (109 mEq/L vs 154 mEq/L in normal saline), avoiding hyperchloremic acidosis
• Includes 4 mEq/L potassium
• 5% dextrose prevents hypoglycemia

Adult Maintenance Fluid Rates

For adults, the standard maintenance rate is 25-30 mL/kg/day, which should NOT exceed this volume unless replacing ongoing losses. 1 This translates to approximately 1-1.25 mL/kg/hr for continuous infusion. 1

Adjustments Based on Patient Characteristics

Use actual body weight for lean individuals and ideal body weight for obese patients when calculating maintenance rates. 3 Adipose tissue is metabolically inactive and does not require proportional fluid maintenance. 3

Young adults with higher metabolic rates require proportionally more fluid per kilogram than older adults. 3 Elderly patients may require 20-30% less than calculated standard maintenance due to age-related metabolic decline. 3

Fluid Composition for Adults

Use isotonic balanced crystalloid solutions (such as Lactated Ringer's or Plasma-Lyte) rather than 0.9% saline for maintenance therapy in adults. 1, 2 Normal saline causes hyperchloremic acidosis, decreased renal blood flow, and impaired gastric motility. 1

Critical Monitoring Requirements

Check serum sodium within 24 hours of starting maintenance IVF, especially in high-risk patients. 2 Monitor electrolytes every 2-4 hours in critically ill patients until stable. 1

Maintain fluid balance charts for all patients receiving IV fluids. 4 Document input/output meticulously, as fluid overload of as little as 2.5 L can cause adverse effects including increased complications and prolonged hospital stay. 1

Important Clinical Caveats

Discontinue maintenance IVF as soon as the patient can tolerate oral intake. 1, 2 For most surgical patients, IV fluids should be unnecessary beyond postoperative day 1, except for upper gastrointestinal and pancreatic procedures. 1

Never prescribe maintenance fluids for patients already on adequate oral intake—this leads to fluid creep and overload. 5 Fluids should be treated as drugs and prescribed only when indicated, not as routine maintenance. 5

Avoid permissive hypotension strategies in patients with traumatic brain injury or spinal cord injury, as adequate perfusion pressure is crucial for central nervous system oxygenation. 1 These patients require different fluid management approaches. 1

Excluded Populations Requiring Specialized Approaches

The standard maintenance formulas do NOT apply to: 1

• Neonates <28 days old
• Patients with neurosurgical disorders
• Congenital or acquired cardiac disease
• Hepatic disease or cirrhosis
• Active cancer
• Renal dysfunction
• Diabetes insipidus
• Voluminous watery diarrhea
• Severe burns

These patients require individualized fluid restriction and closer monitoring due to impaired sodium/water excretion or altered fluid dynamics. 1, 2

Perioperative Considerations

In the perioperative period, reduce basal insulin by 25% the evening before surgery when using maintenance fluids. 1 Monitor blood glucose every 2-4 hours while the patient is NPO. 1

Target perioperative blood glucose of 80-180 mg/dL (4.4-10.0 mmol/L); stricter goals increase hypoglycemia risk without improving outcomes. 1