A nurse is preparing to administer ephedrine 3 mg/kg/day IV bolus divided in equal doses every 6 hr to a school-age child who weighs 70 lb. Available is ephedrine injection 50 mg/mL. How many mL should the nurse administer per dose?
(Round the answer to the nearest hundredth. Use a leading zero if it applies. Do not use a trailing zero.)
The Correct Answer and Explanation is:
To determine the correct volume of ephedrine to administer per dose to a school-age child weighing 70 pounds, we first need to convert the child’s weight from pounds to kilograms, as the medication dosage is specified in mg/kg/day.
Step 1: Convert Weight to Kilograms
1 kg is approximately 2.2 lb. Therefore, to convert the weight:Weight in kg=70 lb2.2 lb/kg≈31.82 kg\text{Weight in kg} = \frac{70 \text{ lb}}{2.2 \text{ lb/kg}} \approx 31.82 \text{ kg}Weight in kg=2.2 lb/kg70 lb≈31.82 kg
Step 2: Calculate Total Daily Dosage
The prescribed dosage is 3 mg/kg/day. We can calculate the total daily dose:Total Daily Dose=3 mg/kg×31.82 kg≈95.46 mg/day\text{Total Daily Dose} = 3 \text{ mg/kg} \times 31.82 \text{ kg} \approx 95.46 \text{ mg/day}Total Daily Dose=3 mg/kg×31.82 kg≈95.46 mg/day
Step 3: Calculate the Dosage per Administration
The medication is to be administered every 6 hours, which means there are 4 doses in a day. To find the dose for each administration, we divide the total daily dose by the number of doses:Dose per administration=95.46 mg4≈23.86 mg\text{Dose per administration} = \frac{95.46 \text{ mg}}{4} \approx 23.86 \text{ mg}Dose per administration=495.46 mg≈23.86 mg
Step 4: Determine the Volume to Administer
Next, we need to find out how many mL correspond to the calculated dose of 23.86 mg. The concentration of the available ephedrine injection is 50 mg/mL. To calculate the volume to be administered, we use the formula:Volume (mL)=Dose (mg)Concentration (mg/mL)\text{Volume (mL)} = \frac{\text{Dose (mg)}}{\text{Concentration (mg/mL)}}Volume (mL)=Concentration (mg/mL)Dose (mg)
Substituting the values we have:Volume=23.86 mg50 mg/mL=0.4772 mL\text{Volume} = \frac{23.86 \text{ mg}}{50 \text{ mg/mL}} = 0.4772 \text{ mL}Volume=50 mg/mL23.86 mg=0.4772 mL
Step 5: Round to the Nearest Hundredth
When rounding to the nearest hundredth, we get:Volume=0.48 mL\text{Volume} = 0.48 \text{ mL}Volume=0.48 mL
Conclusion
The nurse should administer 0.48 mL of ephedrine per dose to the child. This calculation ensures the child receives the appropriate medication dose based on their weight, adhering to safe and effective nursing practices.