Maternity Nursing: cram pack

Formula sheets, the key method steps for every topic and 6 practice problems, with full solutions at the back.

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1Formulas and methods

Maternity & obstetric nursing

Method

  1. Place the woman in time: weeks of pregnancy, stage of labour or day after birth, and decide what is normal at that point.
  2. Look for the patient in danger: the mother, the fetus or the newborn, or more than one of them.
  3. Link the finding to its cause: VEAL CHOP for decelerations, the four Ts for bleeding, BUBBLE-HE after birth.
  4. Choose the action that improves blood flow and oxygen first (side-lying, stopping oxytocin, fundal massage), then escalate.

Dosage calculations

Dose from strength
volume = dose / strength
Weight-based dose
dose = mg/kg × body weight
Tablets
number = dose / tablet strength
Units
1 g = 1000 mg, 1 mg = 1000 mcg

Method

  1. Convert the ordered dose and the stock strength to the same unit.
  2. Use desired over have times quantity: (D/H) × Q.
  3. For weight-based doses, multiply by the weight in kg first, then divide the daily dose by the number of doses.
  4. Estimate first and check that the answer is reasonable.

IV infusion rates

Pump rate
mL/h = volume (mL)/time (h)
Drip rate
drops/min = volume (mL) × drop factor / time (min)
Infusion time
time (h) = volume (mL)/rate (mL/h)

Method

  1. Pump rate in mL/h: volume divided by time in hours.
  2. Drip rate in drops/min: volume × drop factor divided by time in minutes.
  3. For time remaining: volume left divided by the rate.
  4. Round as the question or the equipment requires.

2Practice problems

1.Maternity & obstetric nursingMedium

Misoprostol is given for postpartum haemorrhage. Which side effect is common?

  1. ASevere hypertension
  2. BBradycardia and hypoglycaemia
  3. CBronchospasm in all patients
  4. DShivering and fever
2.Maternity & obstetric nursingHard

A woman at 30 weeks has regular painful contractions every 5 minutes with cervical change. Which treatment is expected to protect the baby's lungs if birth occurs?

  1. AAnti-D immunoglobulin
  2. BOxytocin
  3. CMethylergonovine
  4. DAntenatal corticosteroids
3.Dosage calculationsMedium
5%10 mLm = ? mg

How many milligrams of drug m are in 10 mL of a 5% (w/v) solution?

5% w/v10 mL
m = mg
4.Dosage calculationsHard
22 kg104 cmBSA = √(h·w/3600)25 mg/m²D = ? mg

A patient is 104 cm tall and weighs 22 kg. The prescription is 25 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

104 cm22 kg25 mg/m²
D = mg
5.IV infusion ratesMedium
250 mL10 gtt/mL5 h? gtt/min

Infuse 250 mL over 5 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

250 mL5 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
1 g250 mL? mL/h0.5 mg/min

A bag contains 1 g of a drug in 250 mL. The order is 0.5 mg per minute. At what rate R do you set the pump, in mL/h?

1 g/250 mL0.5 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: D · Shivering and fever

Why this is the answer

Misoprostol, a prostaglandin E1 analogue, commonly causes shivering and a raised temperature, as well as nausea and diarrhoea. It is useful where other uterotonics are not available.

Answer

D · Shivering and fever
2.Maternity & obstetric nursing

Answer: D · Antenatal corticosteroids

Why this is the answer

Antenatal corticosteroids reduce respiratory distress in preterm babies. Tocolysis may be used to gain time, and magnesium sulfate may be given for fetal neuroprotection when birth before about 32 weeks is likely.

Answer

D · Antenatal corticosteroids
3.Dosage calculations

Answer: m = 500 mg

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.

Concentration

5% = 5 g/100 mL = 50 mg/mL

Mass of drug

m = 50·10 = 500 mg

Answer

m = 500 mg
4.Dosage calculations

Answer: D = 19.93 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).

Body surface area

BSA = √(104·22/3600) = √0.6356 = 0.7972 m²

Dose

D = 25·0.7972 = 19.93 mg

Answer

D = 19.93 mg
5.IV infusion rates

Answer: R = 8 gtt/min

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

5·60 = 300 min

Drip rate

R = 250·10/300 = 8.333 ≈ 8 gtt/min

Answer

R = 8 gtt/min

At the bedside you round to the nearest whole drop: 8 gtt/min.

6.IV infusion rates

Answer: R = 7.5 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).

Concentration

1000 mg/250 mL = 4 mg/mL

Dose per hour

0.5·60 = 30 mg/h

Pump rate

R = 30/4 = 7.5 mL/h

Answer

R = 7.5 mL/h

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