ATI RN Nursing Care of Children
Dosage Calculations 3.1 with
Explained Answers
A nurse is preparing to administer dextrose 5% in water 800 mL IV to infuse over 6 hr
to an adolescent client. The nurse should set the IV pump to deliver how many mL/hr?
(Round the answer to the nearest whole number. Use a leading zero if it applies. Do not
use a trailing zero.)
RATIONALE
To calculate this, divide the volume of the infusion by the infusion time to find the rate:
800 mL / 6 hr =
133.33 mL/hr, which rounds to 133 mL/hr when rounded to the nearest whole number.
A nurse is preparing to administer morphine 0.1 mg/kg IV bolus every 3 to 4 hr PRN for
pain to a school-age child who weighs 51 lb. Available is morphine injection 2 mg/mL.
How many mL should the nurse administer per dose? (Round the answer to the nearest
tenth. Use a leading zero if it applies. Do not use a trailing zero.)
RATIONALE
Step 1 is to convert the child’s weight from pounds to kilograms since the dosage of
morphine is prescribed in mg/kg. We know that 1 kg is approximately equal to 2.2 lb.
So, the child’s weight in kg is:
51 lb ÷ 2.2 = 23.18 kg
Step 2 is to calculate the total amount of morphine the child should receive per dose.
The doctor ordered 0.1 mg of morphine per kg of body weight. So, the total amount of
morphine per dose is:
0.1 mg/kg × 23.18 kg = 2.318 mg
Step 3 is to calculate the volume of morphine injection to be administered. We know
that the available morphine injection has a concentration of 2 mg/mL. So, the volume in
mL is:
2.318 mg ÷ (2 mg/mL) = 1.159 mL
, Rounding this to the nearest tenth gives 1.2 mL. So, the nurse should administer 1.2 mL
of morphine injection per dose.
So, the correct answer is 1.2 mL.
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.)
RATIONALE
To calculate this, first convert the child's weight from pounds to kilograms: 70 lb * (1 kg
/ 2.2 lb) = 31.82 kg. Then, calculate the total daily dose of ephedrine in mg: 3
mg/kg/day * 31.82 kg/day = 95.45 mg/day.
Since the daily dose is divided into equal doses every 6 hours, calculate the dose per
administration: 95.45 mg/day / (24 hr/day / 6 hr/dose) = 23.86 mg/dose.
Finally, divide the dose in mg by the concentration of the ephedrine injection to find the
volume to administer: 23.86 mg / (50 mg/mL) = 0.477 mL, which rounds to 0.48mL
when rounded to the nearest hundredth.
A nurse is reviewing a new prescription for dexamethasone 0.2 mg/kg/day PO in two
divided doses for a child who weighs 66 lb. The amount available is dexamethasone 0.5
mg/5 mL elixir. How many mL should the nurse administer per dose? (Round the
answer to the nearest whole number. Use a leading zero if it applies. Do not use a
trailing zero.)
RATIONALE
To calculate this, first convert the child's weight from pounds to kilograms: 66 lb * (1 kg
/ 2.2 lb) = 30 kg. Then, calculate the total daily dose of dexamethasone in mg: 0.2
mg/kg/day * 30 kg/day = 6 mg/day.
Since the daily dose is divided into two doses, calculate the dose per administration: 6
mg/day / 2 doses/day = 3 mg/dose.
Finally, divide the dose in mg by the concentration of the dexamethasone elixir to find
the volume to administer: 3 mg / (0.5 mg/5 mL) = 30 mL/dose, which rounds to 15 mL
when rounded to the nearest whole number.
Dosage Calculations 3.1 with
Explained Answers
A nurse is preparing to administer dextrose 5% in water 800 mL IV to infuse over 6 hr
to an adolescent client. The nurse should set the IV pump to deliver how many mL/hr?
(Round the answer to the nearest whole number. Use a leading zero if it applies. Do not
use a trailing zero.)
RATIONALE
To calculate this, divide the volume of the infusion by the infusion time to find the rate:
800 mL / 6 hr =
133.33 mL/hr, which rounds to 133 mL/hr when rounded to the nearest whole number.
A nurse is preparing to administer morphine 0.1 mg/kg IV bolus every 3 to 4 hr PRN for
pain to a school-age child who weighs 51 lb. Available is morphine injection 2 mg/mL.
How many mL should the nurse administer per dose? (Round the answer to the nearest
tenth. Use a leading zero if it applies. Do not use a trailing zero.)
RATIONALE
Step 1 is to convert the child’s weight from pounds to kilograms since the dosage of
morphine is prescribed in mg/kg. We know that 1 kg is approximately equal to 2.2 lb.
So, the child’s weight in kg is:
51 lb ÷ 2.2 = 23.18 kg
Step 2 is to calculate the total amount of morphine the child should receive per dose.
The doctor ordered 0.1 mg of morphine per kg of body weight. So, the total amount of
morphine per dose is:
0.1 mg/kg × 23.18 kg = 2.318 mg
Step 3 is to calculate the volume of morphine injection to be administered. We know
that the available morphine injection has a concentration of 2 mg/mL. So, the volume in
mL is:
2.318 mg ÷ (2 mg/mL) = 1.159 mL
, Rounding this to the nearest tenth gives 1.2 mL. So, the nurse should administer 1.2 mL
of morphine injection per dose.
So, the correct answer is 1.2 mL.
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.)
RATIONALE
To calculate this, first convert the child's weight from pounds to kilograms: 70 lb * (1 kg
/ 2.2 lb) = 31.82 kg. Then, calculate the total daily dose of ephedrine in mg: 3
mg/kg/day * 31.82 kg/day = 95.45 mg/day.
Since the daily dose is divided into equal doses every 6 hours, calculate the dose per
administration: 95.45 mg/day / (24 hr/day / 6 hr/dose) = 23.86 mg/dose.
Finally, divide the dose in mg by the concentration of the ephedrine injection to find the
volume to administer: 23.86 mg / (50 mg/mL) = 0.477 mL, which rounds to 0.48mL
when rounded to the nearest hundredth.
A nurse is reviewing a new prescription for dexamethasone 0.2 mg/kg/day PO in two
divided doses for a child who weighs 66 lb. The amount available is dexamethasone 0.5
mg/5 mL elixir. How many mL should the nurse administer per dose? (Round the
answer to the nearest whole number. Use a leading zero if it applies. Do not use a
trailing zero.)
RATIONALE
To calculate this, first convert the child's weight from pounds to kilograms: 66 lb * (1 kg
/ 2.2 lb) = 30 kg. Then, calculate the total daily dose of dexamethasone in mg: 0.2
mg/kg/day * 30 kg/day = 6 mg/day.
Since the daily dose is divided into two doses, calculate the dose per administration: 6
mg/day / 2 doses/day = 3 mg/dose.
Finally, divide the dose in mg by the concentration of the dexamethasone elixir to find
the volume to administer: 3 mg / (0.5 mg/5 mL) = 30 mL/dose, which rounds to 15 mL
when rounded to the nearest whole number.
