HESI RN
RN Hesi Med Surg Dosage Calculations Questions
Question 1 of 5
The healthcare provider prescribes amoxicillin 500 mg every 8 hours for a child who weighs 88 pounds. The recommended maximum safe dose is 50 mg/kg/24 hour. The available suspension is labeled, Amoxicillin Suspension 250 mg/5 mL. Based on this child weight, how many mL should the nurse administer? (Enter numerical value only. (If rounding is required, round to the whole number.))
Correct Answer: 10
Rationale:
To determine the volume to administer, first convert the child's weight from pounds to kilograms: 88 pounds × 0.454 kg/pound = 39.952 kg (rounded to 40 kg). The safe dose is 50 mg/kg/24 hours, so 50 × 40 = 2000 mg/day. The prescribed dose is 500 mg every 8 hours, or 500 × 3 = 1500 mg/day, which is safe. The suspension is 250 mg/5 mL. Set up a proportion: 250 mg / 5 mL = 500 mg / x mL. Solving, x = (500 × 5) / 250 = 10 mL.
Question 2 of 5
An adult client receives a prescription for diphenhydramine 15 mL by mouth every 12 hours PRN for pruritus. The bottle is labeled, diphenhydramine 12.5 mg/5 mL. What is the total daily dose in mg that the client receives? (Enter numerical value only.)
Correct Answer: 75
Rationale:
To find the total daily dose, calculate the mg per dose: 12.5 mg/5 mL means 15 mL contains (12.5 × 15) / 5 = 37.5 mg. The prescription allows two doses daily (every 12 hours PRN), so 37.5 × 2 = 75 mg/day.
Question 3 of 5
A 4-year-old is admitted with croup and receives a prescription for a single dose of dexamethasone 0.6 mg/kg IM. The child weighs 35 pounds. How many mg should the nurse administer? (Enter numerical value only. If rounding is required, round to the nearest whole number.)
Correct Answer: 10
Rationale: Convert weight: 35 pounds × 0.454 kg/pound = 15.89 kg (rounded to 16 kg). The dose is 0.6 mg/kg, so 16 × 0.6 = 9.6 mg, rounded to 10 mg.
Question 4 of 5
A client scheduled for coronary artery bypass surgery is to receive an intravenous infusion of 1 gram cefazolin in 50 mL 0.9% Sodium Chloride, USP over 30 minutes. The nurse should program the infusion pump to deliver how many mL/hour? (Enter numeric value only, as a whole number.)
Correct Answer: 100
Rationale: Infusion rate = Volume / Time. Volume is 50 mL, time is 30 minutes = 0.5 hours. So, 50 / 0.5 = 100 mL/hour.
Question 5 of 5
A client who weighs 91 kg receives a prescription for a continuous infusion of dopamine at 3 mcg/kg/min. The solution is labeled, 'Dopamine 400 mg in 5% Dextrose Injection 250 mL.' How many mL/hr should the nurse program the infusion pump to deliver? (Enter numeric value only. If rounding is required, round to the nearest tenth.)
Correct Answer: 10.2
Rationale: Calculate dose: 3 mcg/kg/min × 91 kg = 273 mcg/min. Convert to hourly: 273 × 60 = 16380 mcg/hour. Concentration: 400 mg = 400000 mcg in 250 mL = 1600 mcg/mL. Infusion rate = 16380 / 1600 = 10.2375 mL/hour, rounded to 10.2.