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Difficulty: Very hardPharmacological and Parenteral Therapies

A pediatric client with neuroblastoma is scheduled to receive a cyclophosphamide infusion. The client's height is 144 cm144 \text{ cm} and weight is 36 kg36 \text{ kg}. The provider prescribes cyclophosphamide 825 mg/m2825 \text{ mg/m}^2 IV to infuse continuously over 4 hours4 \text{ hours}. The Mosteller formula for calculating Body Surface Area (BSA) is provided: BSA (m2)=Height (cm)×Weight (kg)3600\text{BSA (m}^2) = \sqrt{\frac{\text{Height (cm)} \times \text{Weight (kg)}}{3600}}. The pharmacy dispenses reconstituted cyclophosphamide with a concentration of 20 mg/mL20 \text{ mg/mL}. The nurse must draw up the prescribed dose and inject it into a 150 mL150 \text{ mL} bag of 0.9%0.9\% sodium chloride for administration.

What should the nurse set the intravenous infusion pump rate to in mL/hr? (Round the final answer to the nearest tenth.)

Answer: 49.9 mL/hr

Answer

49.9
The correct infusion rate is determined by accurately calculating the body surface area (1.2 m^2), using it to find the total medication dose (990 mg), determining the medication volume based on concentration (49.5 mL), adding this medication volume to the base IV fluid volume to find the total volume (199.5 mL), and dividing by the total infusion time (4 hours). Finally, the unrounded rate of 49.875 mL/hr must be correctly rounded to the nearest tenth (49.9 mL/hr).

Step-by-Step Solution

1
Calculate the Body Surface Area (BSA) using the Mosteller formula.
BSA = 1.2 m^2
The prescribed dose is based on body surface area, which must be accurately determined first using the client's height and weight.
2
Calculate the required total dose in milligrams.
990 mg
Multiplying the prescribed dose (825 mg/m^2) by the client's BSA (1.2 m^2) determines the absolute amount of medication needed.
3
Calculate the volume of medication to draw from the vial.
49.5 mL
Dividing the required dose (990 mg) by the vial concentration (20 mg/mL) yields the volume of reconstituted medication to administer.
4
Calculate the total volume of the infusion.
199.5 mL
The IV pump will infuse the entire contents of the bag, so the total volume must account for both the base IV fluid (150 mL) and the added medication (49.5 mL).
5
Calculate the final IV pump infusion rate and round to the nearest tenth.
49.9 mL/hr
Dividing the total infusion volume (199.5 mL) by the infusion time (4 hours) gives 49.875 mL/hr, which rounds to 49.9 mL/hr.

Key Concept

Safe parenteral therapy administration requires accurate multi-step calculation of Body Surface Area (BSA), appropriate conversion of dose to volume, and inclusion of the medication volume into the total diluent volume when programming continuous infusion pump rates.
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Topics

Pharmacological and Parenteral Therapies

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