A physician orders Dobutamine 10 mcg/kg/min for a patient. The patient is 110 lb.
How many milligrams per hour should the patient receive?
A.
0.5 mg/hr
B.
30 mg/hr
C.
60 mg/hr
D.
145 mg/hr
The Correct Answer and Explanation is:
To calculate the amount of Dobutamine the patient should receive per hour, follow these steps:
- Convert the patient’s weight from pounds to kilograms:The patient weighs 110 lb. To convert this to kilograms, use the conversion factor: 1 lb ≈ 0.4536 kg.Weight in kg=110 lb×0.4536 kg/lb≈49.9 kg\text{Weight in kg} = 110 \text{ lb} \times 0.4536 \text{ kg/lb} \approx 49.9 \text{ kg}Weight in kg=110 lb×0.4536 kg/lb≈49.9 kg
- Calculate the total dosage in micrograms per minute:The ordered dosage is 10 mcg/kg/min. Multiply this by the patient’s weight in kg:Dosage in mcg/min=10 mcg/kg/min×49.9 kg≈499 mcg/min\text{Dosage in mcg/min} = 10 \text{ mcg/kg/min} \times 49.9 \text{ kg} \approx 499 \text{ mcg/min}Dosage in mcg/min=10 mcg/kg/min×49.9 kg≈499 mcg/min
- Convert the dosage to milligrams per minute:There are 1,000 micrograms (mcg) in a milligram (mg). Convert the dosage to mg:Dosage in mg/min=499 mcg/min1,000≈0.499 mg/min\text{Dosage in mg/min} = \frac{499 \text{ mcg/min}}{1,000} \approx 0.499 \text{ mg/min}Dosage in mg/min=1,000499 mcg/min≈0.499 mg/min
- Calculate the dosage per hour:There are 60 minutes in an hour. To find the total dosage in mg per hour, multiply the dosage per minute by 60:Dosage in mg/hr=0.499 mg/min×60≈29.94 mg/hr\text{Dosage in mg/hr} = 0.499 \text{ mg/min} \times 60 \approx 29.94 \text{ mg/hr}Dosage in mg/hr=0.499 mg/min×60≈29.94 mg/hrRounding this to the nearest whole number gives approximately 30 mg/hr.
Correct Answer: B. 30 mg/hr
Explanation:
The calculation begins with converting the patient’s weight from pounds to kilograms since drug dosages are often based on weight in kg. The next step is to determine the dosage in micrograms per minute by multiplying the dosage per kilogram by the patient’s weight. Converting this dosage into milligrams involves dividing by 1,000, since there are 1,000 micrograms in a milligram. Finally, to find out the total dosage per hour, the per-minute dosage is multiplied by 60, resulting in the total dosage in milligrams per hour. This process ensures accurate dosage calculations essential for effective and safe medication administration.