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

A woman at 28 weeks is Rh-negative and has a positive antibody screen for anti-D. What does this mean?

  1. AHer baby is definitely Rh-negative
  2. BThe result is normal and needs no further action
  3. CShe is sensitised; the fetus is watched for anaemia
  4. DShe needs a double dose of anti-D immunoglobulin
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. AMethylergonovine
  2. BOxytocin
  3. CAntenatal corticosteroids
  4. DAnti-D immunoglobulin
3.Dosage calculationsMedium
024681010 mL

A child weighing 7 kg is prescribed 20 mg/kg of a drug. The stock solution contains 50 mg/mL. Draw up the dose: what volume V do you give?

7 kg20 mg/kg50 mg/mL
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 445 micrograms. The ampoule contains 0.5 mg/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

445 mcg0.5 mg/mL
V = mL
5.IV infusion ratesMedium
1500 mL15 gtt/mL4 h? gtt/min

Infuse 1500 mL over 4 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1500 mL4 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
1000 mg500 mL5 mL/h? mg/h

A bag contains 1000 mg of a drug in 500 mL and runs at 5 mL/h. How many milligrams per hour D does the patient receive?

1000 mg/500 mL5 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: C · She is sensitised; the fetus is watched for anaemia

Why this is the answer

If antibodies are already present, anti-D prophylaxis is of no use. Antibody levels are followed and the fetus is monitored for anaemia, often with Doppler of the middle cerebral artery.

Answer

C · She is sensitised; the fetus is watched for anaemia
2.Maternity & obstetric nursing

Answer: C · 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

C · Antenatal corticosteroids
3.Dosage calculations

Answer: V = 2.8 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.

Dose from body weight

D = 20·7 = 140 mg

Volume

V = 140/50 = 2.8 mL

On the syringe

On this 10 mL syringe every small line is 0.2 mL.

Answer

V = 2.8 mL
4.Dosage calculations

Answer: V = 0.89 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.

Same units

0.5 mg/mL = 500 mcg/mL

Volume

V = 445/500 = 0.89 mL

Answer

V = 0.89 mL
5.IV infusion rates

Answer: R = 94 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

4·60 = 240 min

Drip rate

R = 1500·15/240 = 93.75 ≈ 94 gtt/min

Answer

R = 94 gtt/min

At the bedside you round to the nearest whole drop: 94 gtt/min.

6.IV infusion rates

Answer: D = 10 mg/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.

Concentration

1000/500 = 2 mg/mL

Dose rate

D = 2·5 = 10 mg/h

Answer

D = 10 mg/h

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