A nurse is preparing to administer milrinone 50 mcg/kg IV loading dose to a client who weighs 154 lb. Available is milrinone 1 mg/mL. How many mL should the nurse administer? (Round the answer to the nearest tenth. Use a leading zero if it applies. Do not use a trailing zero.)
The correct answer and Explanation is :
To determine how many mL of milrinone to administer, follow these steps:
- Convert the client’s weight from pounds to kilograms:
- Weight in pounds: 154 lb
- Conversion factor: 1 lb = 0.453592 kg
- Weight in kilograms: ( 154 \, \text{lb} \times 0.453592 \, \text{kg/lb} = 69.85 \, \text{kg} ) (rounded to two decimal places)
- Calculate the total dose required:
- Dosage ordered: 50 mcg/kg
- Weight of the client: 69.85 kg
- Total dose (in mcg): ( 50 \, \text{mcg/kg} \times 69.85 \, \text{kg} = 3492.5 \, \text{mcg} )
- Convert the dose from mcg to mg:
- Conversion factor: 1000 mcg = 1 mg
- Total dose (in mg): ( \frac{3492.5 \, \text{mcg}}{1000} = 3.4925 \, \text{mg} )
- Determine the volume to administer:
- Concentration available: 1 mg/mL
- Volume required (in mL): ( \frac{3.4925 \, \text{mg}}{1 \, \text{mg/mL}} = 3.4925 \, \text{mL} )
- Round to the nearest tenth:
- Volume to administer: 3.5 mL
Explanation:
- Weight Conversion: The weight of the client needs to be converted from pounds to kilograms because drug dosages are often calculated based on kilograms.
- Dose Calculation: The prescribed dose is based on weight in kilograms. By multiplying the dosage (50 mcg/kg) by the client’s weight in kilograms, the total amount of drug needed in micrograms is determined.
- Unit Conversion: Since drug concentrations are typically given in mg/mL but the calculated dose is in mcg, a conversion to milligrams is necessary.
- Volume Determination: With the concentration provided (1 mg/mL), dividing the total dose (in mg) by this concentration gives the volume to be administered in milliliters.
- Rounding: Finally, the answer is rounded to the nearest tenth for practical administration.
Thus, the nurse should administer 3.5 mL of milrinone.