Final answer:
To find the infusion rate in ml/hr for a 140-lb patient given a 0.6% drug solution, convert the weight to kg, calculate the total daily drug amount in mg, convert the solution concentration, and then use these values to calculate the rate. The infusion rate is approximately 19.9 mL/hr.
Step-by-step explanation:
To calculate the infusion rate in ml/hr for a patient weighing 140 lbs, we must first convert the patient's weight from pounds to kilograms, determine the total daily dose in milligrams, convert the drug concentration from percentage to milligrams per milliliter, and then calculate the infusion rate.
Step 1: Convert the patient's weight from pounds to kilograms. Since 1 pound is equivalent to 0.453592 kilograms,
140 lbs × 0.453592 kg/lb = 63.5 kg (rounded to one decimal place).
Step 2: Calculate the total daily dose in milligrams using the provided dose of 45 mg/kg/day.
63.5 kg × 45 mg/kg = 2857.5 mg/day (rounded to one decimal place).
Step 3: Convert the drug concentration from percentage to milligrams per milliliter. A 0.6% solution means there are 0.6 grams of drug per 100 mL of solution, which is equivalent to 600 mg per 100 mL or 6 mg/mL.
Step 4: Calculate the infusion rate in ml/hr.
Since there are 2857.5 mg/day to administer and 6 mg is present in each milliliter of solution, the total volume of solution needed per day is:
2857.5 mg/day ÷ 6 mg/mL = 476.25 mL/day.
There are 24 hours in a day, so to find the infusion rate in ml/hr:
476.25 mL/day ÷ 24 hr/day = 19.84 mL/hr, which we can round to 19.9 mL/hr.