Lippincott Nursing Pocket Card - July 2025
Calculating Maintenance IV Fluid Rate
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Maintenance Intravenous (IV) Fluids
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Maintenance intravenous (IV) fluids are crystalloid solutions administered to patients who are not eating or drinking adequately to prevent dehydration and maintain normal fluid and electrolyte balance. They are distinct from replacement fluids, which are given to correct existing volume deficits or ongoing abnormal losses.
Calculating the infusion rate will ensure that patients receive the appropriate amount of fluid. Several methods are used, with the "4-2-1 rule" and body weight-based calculations being the most common.
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Calculations
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| The "4-2-1 Rule" (for children and some adults) |
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This widely used rule provides an hourly maintenance fluid rate based on body weight.
- For the first 10 kg of body weight: 4 mL/kg/hour
- For the next 10 kg of body weight (i.e., 11-20 kg): 2 mL/kg/hour
- For every kg over 20 kg: 1 mL/kg/hour
Example (4-2-1 Rule): calculate the maintenance fluid rate for a 25 kg child:
- First 10 kg: 10 kg × 4 mL/kg/hour= 40 mL/hour
- Next 10 kg: 10 kg × 2 mL/kg/hour= 20 mL/hour
- Remaining 5 kg (25 kg - 20 kg): 5 kg × 1 mL/kg/hour= 5 mL/hour
Total Hourly Rate: [40 mL/hour] + [20 mL/hour] + [5 mL/hour] = 65 mL/hour
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| Body Weight-Based Calculation (24-hour method) |
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This method calculates the total 24-hour fluid requirement and then divides it by 24 to get the hourly rate. It is often used for adults.
- For the first 10 kg of body weight: 100 mL/kg/day
- For the next 10 kg of body weight (e.g., 11-20 kg): 50 mL/kg/day
- For every kg over 20 kg: 20 mL/kg/day
Example (24-hour method): calculate the maintenance fluid rate for a 70 kg adult:
- First 10 kg: 10 kg × 100 mL/kg/day = 1000 mL/day
- Next 10 kg: 10 kg × 50 mL/kg/day = 500 mL/day
- Remaining 50 kg (70 kg - 20 kg): 50 kg × 20 mL/kg/day = 1000 mL/day
Total Daily Rate: [1000 mL/day] + [500 mL/day] + [1000 mL/day] = 2500 mL/day
Hourly Rate: [2500 mL/day]/[24 hours/day] ≈ 104 mL/hour
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| Note: The 4-2-1 rule and the 24-hour method for adults will yield very similar results when divided by 24, as the 4-2-1 rule is essentially a simplified hourly version of the 24-hour method. |
General Guideline for Adults
For many adult patients without specific fluid restrictions or high fluid losses, a general guideline for maintenance fluid is often 30-40 mL/kg/day. This is a quick estimation.
Example Calculation (General Guideline): For a 70 kg adult: 70 kg × 30 mL/kg/day = 2100 mL/day
Hourly Rate: [2100 mL/day]/[24 hours/day] ≈ 87.5 mL/hour
Note: This is a general guideline, and the 4-2-1 or 24-hour methods are more precise.
Important Nursing Considerations
- Fluid requirements can vary significantly based on fever, hypermetabolic states, renal function, heart failure, burns, and other conditions. Consult with the provider if there are concerns about the patient's overall clinical picture or the rate of IV fluids.
- Regularly check serum electrolytes (sodium, potassium, chloride, bicarbonate). Usually, providers will order a daily basic metabolic panel for patients receiving IV fluids.
- Monitor for signs of fluid overload, especially in patients with compromised cardiac or renal function. These signs include crackles in the lungs, peripheral edema, jugular venous distension, and increased blood pressure.
- Conversely, monitor for signs of inadequate hydration, such as dry mucous membranes, decreased urine output, poor skin turgor, and thirst.
- Intake and Output charting is essential for monitoring fluid balance.
- Daily weight monitoring is another helpful data element in assessing the volume status of acutely ill patients.
- Always double-check infusion pump programming against the provider’s order to prevent errors.