Formula sheets, the key method steps for every topic and 6 practice problems, with full solutions at the back.
A pregnant woman takes warfarin for a mechanical heart valve. Why is she usually switched to heparin for much of the pregnancy?
A woman 5 hours after birth had a large blood loss and now has a heart rate of 128/min, blood pressure of 88/50 mmHg and cold hands. Which action is most important?
A child weighing 15 kg is prescribed 4 mg/kg of a drug. The stock solution contains 25 mg/mL. Draw up the dose: what volume V do you give?
A patient is 163 cm tall and weighs 74 kg. The prescription is 25 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.
1500 mL was ordered over 10 hours. After 8 hours you find that 390 mL is still in the bag, and the order must still finish on time. To what rate R in mL/h must the pump be reset?
A bag contains 2 g of a drug in 250 mL. The order is 4 mg per minute. At what rate R do you set the pump, in mL/h?
Answer: C · Warfarin crosses the placenta and can harm the fetus
Warfarin crosses the placenta and is teratogenic and can cause fetal bleeding. Heparins are large molecules that do not cross the placenta, so low molecular weight heparin is commonly used instead.
Answer: B · Call for urgent help and start fluid resuscitation
Tachycardia, hypotension and cool peripheries indicate hypovolaemic shock. Help is called, IV access secured, fluids and blood given as prescribed, and the cause of bleeding treated.
Answer: V = 2.4 mL
Drawing up a dose: volume = (prescribed dose/stock strength) × stock volume. Convert to the same units first, then check that the volume fits the syringe and lands on one of its graduations.
On this 10 mL syringe every small line is 0.2 mL.
Answer: D = 45.76 mg
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).
Answer: R = 195 mL/h
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.
This is more than a 25% increase: most hospitals require you to contact the prescriber instead of catching up, and to assess the patient for fluid overload.
Answer: R = 30 mL/h
Dose-based infusions: concentration = amount of drug in the bag/bag volume. Pump rate (mL/h) = dose per hour/concentration, and dose per hour = mL/h × concentration. Convert per-minute doses to per-hour (× 60) and keep the mass units the same (1 g = 1000 mg, 1 mg = 1000 mcg).
ExamProblems · examproblems.com/courses/maternity-nursing