Formula sheets, the key method steps for every topic and 6 practice problems, with full solutions at the back.
A woman at 24 weeks reports burning on urination and urinary frequency. What is the priority action?
A woman with known mitral stenosis is pregnant. When is she at greatest risk of heart failure?
A prefilled syringe of epinephrine (adrenaline) is labelled 1:10 000 (0.1 mg/mL). The prescription is 1 mg IV in cardiac arrest. What volume V do you give?
The prescription is 425 micrograms. The ampoule contains 0.5 mg/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?
1500 mL was ordered over 8 hours. After 3 hours you find that 1140 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 4 g of a drug in 500 mL. The order is 4 mg per minute. At what rate R do you set the pump, in mL/h?
Answer: B · Collect a urine sample for culture and inform the provider
Dysuria suggests a urinary tract infection, which needs culture and treatment with a pregnancy-safe antibiotic. Untreated UTIs can progress to pyelonephritis and preterm labour.
Answer: D · When blood volume peaks in late pregnancy and in the hours after birth
Cardiac decompensation is most likely when blood volume peaks in the late second and third trimester and right after birth, when blood from the contracted uterus returns to the circulation. These women need close monitoring postpartum.
Answer: V = 10 mL
Solution strengths: a percentage strength is grams per 100 mL, so 1% = 1 g/100 mL = 10 mg/mL. A ratio strength 1:1000 means 1 g in 1000 mL = 1 mg/mL; 1:10 000 is 0.1 mg/mL. For a dilution the amount of drug stays the same: C₁·V₁ = C₂·V₂.
US labels now state mg/mL (1 mg/mL = 1:1000; 0.1 mg/mL = 1:10 000). Never give 1 mg/mL epinephrine IV push.
Answer: V = 0.85 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.
Answer: R = 228 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.
Many hospitals allow such an adjustment up to 25% without a new order; check local policy.
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).
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