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

Why is congenital hypothyroidism included in newborn screening?

  1. AEarly treatment prevents brain damage
  2. BIt causes hip dysplasia
  3. CIt causes jaundice that cannot be treated
  4. DIt can only be treated before birth
2.Maternity & obstetric nursingHard

A woman at 26 weeks receiving terbutaline for preterm contractions has a heart rate of 132/min and chest tightness. What should the nurse do?

  1. AGive the next dose early to stop contractions
  2. BIncrease her IV fluids rapidly to lower her heart rate
  3. CReassure her that this is expected and continue
  4. DWithhold the next dose and report the findings
3.Dosage calculationsMedium
024681010 mL

A child weighing 16 kg is prescribed 10 mg/kg of a drug. The stock solution contains 50 mg/mL. Draw up the dose: what volume V do you give?

16 kg10 mg/kg50 mg/mL
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 950 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?

950 units1000 units/mL
V = mL
5.IV infusion ratesMedium
250 mL20 gtt/mL3 h? gtt/min

Infuse 250 mL over 3 hours with a giving set of 20 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

250 mL3 h20 gtt/mL
R = gtt/min
6.IV infusion ratesHard
2 g250 mL? mL/h4 mg/min

A bag contains 2 g of a drug in 250 mL. The order is 4 mg per minute. At what rate R do you set the pump, in mL/h?

2 g/250 mL4 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: A · Early treatment prevents brain damage

Why this is the answer

Untreated congenital hypothyroidism causes poor growth and intellectual disability. Daily levothyroxine started in the first weeks allows normal development.

Answer

A · Early treatment prevents brain damage
2.Maternity & obstetric nursing

Answer: D · Withhold the next dose and report the findings

Why this is the answer

Terbutaline can cause maternal tachycardia, palpitations, chest pain, pulmonary oedema and hyperglycaemia, so it is used only short term. A maternal heart rate above about 120/min or chest pain means the drug should be held and the provider informed.

Answer

D · Withhold the next dose and report the findings
3.Dosage calculations

Answer: V = 3.2 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 = 10·16 = 160 mg

Volume

V = 160/50 = 3.2 mL

On the syringe

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

Answer

V = 3.2 mL
4.Dosage calculations

Answer: V = 0.95 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.

Volume

V = 950/1000 = 0.95 mL

On the syringe

On this 1 mL syringe every small line is 0.01 mL.

Answer

V = 0.95 mL
5.IV infusion rates

Answer: R = 28 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

3·60 = 180 min

Drip rate

R = 250·20/180 = 27.78 ≈ 28 gtt/min

Answer

R = 28 gtt/min

At the bedside you round to the nearest whole drop: 28 gtt/min.

6.IV infusion rates

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).

Concentration

2000 mg/250 mL = 8 mg/mL

Dose per hour

4·60 = 240 mg/h

Pump rate

R = 240/8 = 30 mL/h

Answer

R = 30 mL/h

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