IV Fluids and Fluid Balance: practice problems and exam questions

Maintenance fluids with the Holliday–Segar method, intake and output records, urine output and infusion completion times, all as practice exercises.

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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. IV fluids & fluid balancemaintenance fluids (Holliday–Segar 4-2-1) · intake and output balance · infusion completion timecalculations
  2. IV infusion ratespump rate · drip rate · time and dose ratecalculations

Exam tips for IV Fluids and Fluid Balance

  • Apply each Holliday–Segar band only to the kilograms inside it.
  • Count every intake source, including IV infusions and IV medications.
  • Decimal hours are not hours and minutes: 0.5 h = 30 min.

Worked examples

IV fluids & fluid balanceEasy
maintenance4-2-1? mL/h43 kg

Practice exercise (made-up values, not clinical guidance). Use the Holliday–Segar 4-2-1 rule to find the hourly maintenance fluid rate R in mL/h for a child who weighs 43 kg.

43 kg4-2-1

Find R (mL/h)

Show hints
  1. Split the weight into bands: the first 10 kg, the next 10 kg and the rest.
  2. Multiply each band by its rate: 4, 2 and 1 mL/kg/h.
  3. first 10 kg: 4·10 = 40 mL/h.
Show the answer and the step-by-step solution

Holliday–Segar maintenance: per hour, 4 mL/kg for the first 10 kg, 2 mL/kg for the next 10 kg and 1 mL/kg for every kg above 20 (the 4-2-1 rule). Per day, the same bands use 100, 50 and 20 mL/kg (100-50-20). Each band applies only to the kilograms inside it. The numbers are for practice only; at the bedside always follow local protocols and have high-risk doses double-checked.

Rate per band

first 10 kg: 4·10 = 40 mL/h
next 10 kg: 2·10 = 20 mL/h
each kg above 20: 1·23 = 23 mL/h

Add the bands

R = 83 mL/h

Answer

R = 83 mL/h
IV infusion ratesMedium
1000 mL15 gtt/mL6 h? gtt/min

Infuse 1000 mL over 6 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1000 mL6 h15 gtt/mL

Find R (gtt/min)

Show hints
  1. gtt/min = volume × drop factor/time in minutes.
  2. Convert the hours to minutes first.
  3. 6 h = 360 min.
Show the answer and the step-by-step solution

Infusion rates: a pump is set in mL/h = volume/time in hours. A gravity drip is counted in drops per minute: gtt/min = volume (mL) × drop factor (gtt/mL)/time (min). The drop factor is printed on the tubing package: macrodrip sets deliver 10, 15 or 20 gtt/mL (blood sets often 10 gtt/mL in the US, 15 in the UK) and microdrip sets 60 gtt/mL. Always use the drop factor the question or package gives.

Time in minutes

6·60 = 360 min

Drip rate

R = 1000·15/360 = 41.67 ≈ 42 gtt/min

Answer

R = 42 gtt/min

At the bedside you round to the nearest whole drop: 42 gtt/min.

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

IV flow rate and drip rate calculatorIV infusion time calculator (when will the infusion finish?)Intake and output calculator (fluid balance)Parkland formula calculator (burn fluid resuscitation)Maintenance fluids calculator (Holliday–Segar)

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