Formula sheets, the key method steps for every topic and 6 practice problems, with full solutions at the back.
A woman in labour has severe back pain with each contraction. The fetus is in an occiput posterior position. Which measure is most likely to help?
A labouring woman has a temperature of 38.5 °C (101.3 °F), and the fetal baseline has risen from 140 to 170 bpm over the last hour. What is the most likely explanation?
A dose of 400 mg is needed from a 10% (w/v) solution. What volume V contains this dose?
The prescription is 370 units of a drug that comes as 1000 units/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?
A drip runs at 35 gtt/min through a set of 15 gtt/mL. How many millilitres V does the patient receive in 2 hours?
1000 mL was ordered over 10 hours. After 3 hours you find that 810 mL is still in the bag, and the order must still finish on time. By what percentage Δ must the original pump rate be increased?
Answer: B · Sacral counterpressure and a hands-and-knees position
In occiput posterior positions the fetal head presses on the sacrum. Counterpressure on the lower back and positions such as hands-and-knees or leaning forward ease pain and may help the head rotate.
Answer: D · Fetal tachycardia due to maternal fever or infection
Maternal fever, often from intra-amniotic infection, is a common cause of fetal tachycardia. The provider is informed, and treatment of fever and infection is expected. Opioids reduce variability rather than raise the rate.
Answer: V = 4 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.
Answer: V = 0.37 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 1 mL syringe every small line is 0.01 mL.
Answer: V = 280 mL
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.
Answer: Δ = 15.71 %
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.
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