Final answer:
The correct infusion rate for a child weighing 25 kg, prescribed 1 microgram/kg/min of salbutamol, with a syringe containing 10mg in 50 mL, is 7.5 mL/hr. This is calculated by determining the dosage, converting units, and calculating the volume of infusion per hour. Option C is correct.
Step-by-step explanation:
The question involves calculating the infusion rate in mL/hr for a prescribed dosage of salbutamol based on a child's weight and a given concentration of the drug in a syringe. First, we need to determine the total dosage the child requires per minute and convert that into the total volume to be infused per hour.
To calculate the dosage per minute:
1 microgram/kg/min * 25 kg = 25 micrograms/min
Then convert micrograms to milligrams, noting that 1 mg = 1,000 micrograms:
25 micrograms/min = 0.025 mg/min
To find out how many minutes 10 mg will last (since we have 10 mg in the 50 mL syringe):
10 mg / 0.025 mg/min = 400 min
Now we divide the total volume of the syringe by the total time to find the infusion rate:
50 mL / 400 min = 0.125 mL/min
To convert the rate to mL/hr, multiply by 60 minutes/hr:
0.125 mL/min * 60 min/hr = 7.5 mL/hr
Therefore, the correct infusion rate is 7.5 mL/hr, which corresponds to answer option C.