Pediatric and Critical-Care Dosing: practice problems and exam questions

Practice exercises for weight-based pediatric doses, heparin and insulin infusions, and titrated drips in mcg/kg/min. All values are made up for practice and are not clinical guidance.

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Cram pack (PDF)Formula sheets, method steps and practice problems with full solutions, ready to print.

Topics in this course

  1. Pediatric & critical-care dosingpediatric weight-based doses (mg/kg/day divided) · heparin and insulin infusions (units/h, mL/h) · titrated drips (mcg/kg/min to mL/h)calculations
  2. Dosage calculationstablets and liquids · weight-based doses · doses and concentrationscalculations
  3. IV infusion ratespump rate · drip rate · time and dose ratecalculations

Exam tips for Pediatric and Critical-Care Dosing

  • Find the daily total first, then divide by the number of doses (24 h/interval).
  • Turn the bag into a concentration (units/mL or mcg/mL) before you calculate a rate.
  • Check the order: per kg or not, per minute or per hour, mg or mcg.

Worked examples

Pediatric & critical-care dosingEasy
cephalexin oral suspension250 mg/5 mLper dose: V = ? mL

Practice exercise (made-up values, not clinical guidance). A child weighing 17 kg is prescribed cephalexin 50 mg/kg/day, divided every 12 hours. The oral suspension contains 250 mg in 5 mL. What volume V do you give per dose? Round to one decimal place.

17 kg50 mg/kg/dayevery 12 h250 mg/5 mL

Find V (mL)

Show hints
  1. Find the dose per administration in mg first.
  2. Every 12 hours means 2 doses a day.
  3. 50·17/2 = 425 mg.
Show the answer and the step-by-step solution

Weight-based paediatric doses: daily dose (mg) = dose per kg per day × weight (kg). A daily dose “divided every N hours” is given 24/N times a day, so dose per administration = daily dose/(24/N). Convert pounds to kilograms first (1 kg = 2.2 lb), and turn the dose into a volume with (dose/stock strength) × stock volume. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.

Dose per administration

50·17 = 850 mg/day
850/2 = 425 mg

Volume

V = (425/250)·5 = 8.5 mL

Answer

V = 8.5 mL
Dosage calculationsMedium
17 kgBSA = 0.86 m²250 mg/m²D = ? mg

A patient weighing 17 kg has a body surface area of 0.86 m². The prescription is 250 mg/m². Find the dose D in mg.

17 kgBSA = 0.86 m²250 mg/m²

Find D (mg)

Show hints
  1. The order is per m² of body surface area.
  2. D = dose per m² × BSA. The weight is not needed.
  3. 250·0.86.
Show the answer and the step-by-step solution

Body-surface-area dosing: many cytotoxic and some paediatric doses are prescribed per square metre of body surface area: dose (mg) = dose per m² × BSA (m²). The Mosteller formula estimates BSA = √(height (cm) × weight (kg)/3600).

Dose

D = 250·0.86 = 215 mg

Answer

D = 215 mg

How practising works

  • “Practise this course” mixes problems from all its topics, like a real exam.
  • Every problem has new values, so you learn the method instead of an answer.
  • Stuck? Open a small hint first, and the full explanation only when you need it.
  • Mock exams are timed and have no hints, and you get your score and a full review at the end.

Calculators for this course

Dosage calculator (desired over have)IV flow rate and drip rate calculatorWeight-based dose calculator (mg/kg)mcg/kg/min to mL/h calculator (weight-based infusion)Pediatric safe dose range calculator (mg/kg/day)IV infusion time calculator (when will the infusion finish?)Heparin infusion rate calculator

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