Formula sheets, the key method steps for every topic and 6 practice problems, with full solutions at the back.
Which complication should the nurse monitor for after an epidural is started in labour?
A newborn is pale, has a heart rate of 170/min and weak pulses after a difficult vacuum birth. The scalp is boggy and swelling across the sutures is increasing. What should the nurse suspect?
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?
An infusion contains 40000 units of a drug in 250 mL. The prescription is 1000 units per hour. At what rate R do you set the pump, in mL/h?
1500 mL was ordered over 10 hours. After 2 hours you find that 1340 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?
1500 mL was ordered over 10 hours. After 7 hours you find that 520 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: D · Maternal hypotension
An epidural causes vasodilation, so blood pressure can fall, which reduces blood flow to the placenta. Blood pressure and the fetal heart rate are checked frequently, and bladder distension is common because sensation is reduced.
Answer: C · Subgaleal haemorrhage
A subgaleal haemorrhage is bleeding under the scalp aponeurosis. It crosses suture lines, can grow rapidly and can cause hypovolaemic shock. It is an emergency, unlike caput or cephalhaematoma.
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: R = 6.25 mL/h
Dose calculation: the amount to give equals what is prescribed divided by what you have, times the quantity it comes in: amount = (desired dose/stock strength) × stock volume. Always keep the units the same (convert g to mg, mg to mcg first) and check that the answer is sensible.
Answer: R = 167.5 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: Δ = 15.56 %
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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