How to Calculate the Maintenance of Intravenous Fluids

Written by grace morelli
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How to Calculate the Maintenance of Intravenous Fluids
Intravenous fluids are most often given in a hospital setting. (Comstock/Comstock/Getty Images)

To maintain good health, your body must manage a perfect balance of fluid and electrolytes. During certain illnesses, this balance could be disturbed. A decrease of your body fluids and electrolytes, known as dehydration, is often treated with intravenous fluids. Intravenous fluids are liquid solutions that are put directly into your body, through a vein. The type and amount of intravenous solution you receive will be calculated and prescribed by your doctor. Whether you are prescribing, administering or receiving intravenous fluids, it is important to understand how they are calculated.

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  1. 1

    Assess for signs of dehydration. Some common signs to look for are feeling thirsty, a dry mouth, a decrease in the amount of urine passed, dizziness, low blood pressure, a fast heartbeat and feeling tired. Severe dehydration can quickly become a medical emergency that requires immediate treatment.

  2. 2

    Obtain laboratory values to check for a decrease in electrolyte levels. Sodium, potassium and chloride are important electrolytes that help your body to function normally. If the values are low, they will need to be calculated into the maintenance intravenous fluid. Be prepared to treat dangerously low electrolyte levels quickly.

  3. 3

    Determine the need for intravenous fluid and electrolyte replacement. A doctor will perform a complete medical examination, record a past medical history and analyse laboratory values before deciding if intravenous fluids are needed.

  4. 4

    Calculate the amount of maintenance intravenous fluid that is needed to treat dehydration. The most common calculation, used for both adult and paediatric patients, is the Holliday-Segar Formula. It is a weight-based formula that may be altered by the doctor, based on the specific needs of each patient. The weight is measured in kilograms and the amount of fluid is measured in millilitres.

    Water requirements for 24 hours:

    100ml/kg for the first 10kg

    50ml/kg for the next 10kg (11 -- 20kg)

    20ml/kg for the rest (> 20kg)

    Electrolyte requirements for 24 hours:

    Sodium 30 meq added to 1000 millilitres (ml) of solution

    Potassium 20 meq added to 1000 millilitres (ml) of solution

    Chloride (usually contained in intravenous solution and extra will not need to be added)

  5. 5

    Practice the Holliday-Segar Formula and become familiar with the required calculations. Be sure to get an accurate patient weight, in kilograms, prior to completing your calculations.

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