A nurse is preparing to administer ondansetron 0.15 mg/kg IV to a client who weighs 132 lb. Available is ondansetron 2 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 milliliters (mL) of ondansetron 2 mg/mL should be administered, follow these steps:
- Convert the client’s weight from pounds to kilograms:
- The weight of the client is 132 lb.
- To convert pounds to kilograms, use the conversion factor: 1 kg = 2.20462 lb.
- Weight in kg=Weight in lb2.20462\text{Weight in kg} = \frac{\text{Weight in lb}}{2.20462}Weight in kg=2.20462Weight in lb
- Weight in kg=1322.20462≈59.9 kg\text{Weight in kg} = \frac{132}{2.20462} \approx 59.9 \text{ kg}Weight in kg=2.20462132≈59.9 kg
- Calculate the total dose of ondansetron needed:
- The prescribed dose is 0.15 mg/kg.
- Total dose=Dose per kg×Weight in kg\text{Total dose} = \text{Dose per kg} \times \text{Weight in kg}Total dose=Dose per kg×Weight in kg
- Total dose=0.15 mg/kg×59.9 kg\text{Total dose} = 0.15 \text{ mg/kg} \times 59.9 \text{ kg}Total dose=0.15 mg/kg×59.9 kg
- Total dose≈8.99 mg\text{Total dose} \approx 8.99 \text{ mg}Total dose≈8.99 mg
- Determine the volume of ondansetron solution to administer:
- The concentration of the available ondansetron is 2 mg/mL.
- To find the volume required, use the formula:
- Volume (mL)=Total dose (mg)Concentration (mg/mL)\text{Volume (mL)} = \frac{\text{Total dose (mg)}}{\text{Concentration (mg/mL)}}Volume (mL)=Concentration (mg/mL)Total dose (mg)
- Volume (mL)=8.99 mg2 mg/mL\text{Volume (mL)} = \frac{8.99 \text{ mg}}{2 \text{ mg/mL}}Volume (mL)=2 mg/mL8.99 mg
- Volume (mL)=4.495 mL\text{Volume (mL)} = 4.495 \text{ mL}Volume (mL)=4.495 mL
- Round the answer to the nearest tenth:
- The volume needed is approximately 4.495 mL.
- Rounding 4.495 to the nearest tenth gives 4.5 mL.
Therefore, the nurse should administer 4.5 mL of ondansetron.
Explanation
First, the client’s weight was converted from pounds to kilograms, which is necessary because medication dosages are typically calculated in mg/kg. The conversion from pounds to kilograms involves dividing the weight in pounds by 2.20462.
Next, the total dose of ondansetron required was calculated by multiplying the dose per kilogram by the client’s weight in kilograms. This calculation determines how much ondansetron the client needs based on their body weight.
Finally, the volume of the available ondansetron solution (2 mg/mL) needed to provide the calculated dose was determined. By dividing the total dose by the concentration of the solution, the nurse calculates how many milliliters of the solution to administer. Rounding to the nearest tenth ensures that the dosage is practical and easy to measure.