Maintenance Intravenous Fluid Therapy for Adults
For adult maintenance intravenous fluid therapy, isotonic balanced crystalloid solutions with appropriate glucose and potassium should be used as first-line choice to reduce the risk of hyponatremia and minimize length of stay. 1
Fluid Composition
- Isotonic solutions with sodium concentrations similar to plasma (135-144 mEq/L) are recommended for maintenance IV fluid therapy to prevent hyponatremia 1
- Balanced solutions (such as PlasmaLyte or Lactated Ringer's) should be favored over 0.9% sodium chloride as they reduce length of stay in critically ill and acutely ill patients 1
- Using hypotonic solutions for maintenance therapy significantly increases the risk of hyponatremia and should be avoided 1, 2
- Isotonic saline (0.9% NS) effectively expands the intravascular compartment but large volumes may lead to hyperchloremic metabolic acidosis 3
Additional Components
- Glucose should be included in maintenance fluids in sufficient amounts to prevent hypoglycemia 1
- Appropriate potassium should be added to maintenance fluids based on clinical status and regular monitoring to avoid hypokalemia 1
- Blood glucose monitoring should be performed at least daily to guide glucose provision 1
Volume Considerations
The traditional approach for calculating maintenance fluid requirements in adults is:
- 1500 mL for the first 20 kg of body weight
- 20 mL/kg for each kg above 20 kg
- This is based on the Holliday-Segar formula adapted for adults 4
The total daily amount of maintenance fluid should include all sources (IV fluids, blood products, IV medications, line flush solutions) 1
Fluid overload and cumulative positive fluid balance should be avoided to prevent prolonged mechanical ventilation and extended length of stay 1
Monitoring Parameters
- Regular assessment of fluid balance, clinical status, and electrolytes (especially sodium levels) is recommended at least daily 1
- Serum electrolyte and renal function measurements should be obtained regularly in patients receiving IV fluids 5
- Fluid balance charts should be maintained for all patients receiving IV fluids 5
- Body weight measurements should be documented regularly, though this is often underutilized in clinical practice 5
Special Considerations
- In patients with heart failure, renal failure, or hepatic failure, maintenance fluid volume should be restricted to 50-60% of the calculated volume 1
- For patients at risk of increased ADH secretion, restricting maintenance fluid to 65-80% of the calculated volume should be considered 1
- Avoid using lactate buffer solutions in patients with severe liver dysfunction to prevent lactic acidosis 6
Common Pitfalls to Avoid
- Using hypotonic solutions for maintenance therapy significantly increases the risk of hyponatremia 1, 7
- Failing to account for all sources of fluid when calculating total maintenance volume can lead to "fluid creep" and overload 1
- Inadequate monitoring of electrolytes and fluid balance can lead to undetected complications 5
- Continuing IV fluids when oral intake is adequate or possible delays transition to enteral hydration 6