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

What should parents be taught about the water for a newborn's bath?

  1. AAdd adult bubble bath to soften the baby's skin
  2. BUse very hot water so that germs on the skin are killed
  3. CLeave the baby briefly if the water is only shallow
  4. DCheck that it is warm, not hot, before the baby goes in
2.Maternity & obstetric nursingHard

A newborn's bilirubin is rising quickly at 30 hours despite phototherapy, and the baby is lethargic with an arched back and high-pitched cry. What does this suggest?

  1. ANormal newborn reflexes
  2. BA normal reaction to phototherapy
  3. CAcute bilirubin encephalopathy
  4. DMild breast milk jaundice
3.Dosage calculationsMedium
024681010 mL

A child weighing 18 kg is prescribed 5 mg/kg of a drug. The stock solution contains 50 mg/mL. Draw up the dose: what volume V do you give?

18 kg5 mg/kg50 mg/mL
V = mL
4.Dosage calculationsHard
63 kg165 cmBSA = √(h·w/3600)100 mg/m²D = ? mg

A patient is 165 cm tall and weighs 63 kg. The prescription is 100 mg/m². Using the Mosteller formula BSA = √(height (cm) × weight (kg)/3600), find the dose D in mg.

165 cm63 kg100 mg/m²
D = mg
5.IV infusion ratesMedium
15 gtt/mL40 mL/h? gtt/min

An infusion is ordered at 40 mL/h, but no pump is available. It runs by gravity through a giving set of 15 gtt/mL. Find the drip rate R in drops per minute.

40 mL/h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
500 mg500 mL10 mL/h? mg/h

A bag contains 500 mg of a drug in 500 mL and runs at 10 mL/h. How many milligrams per hour D does the patient receive?

500 mg/500 mL10 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: D · Check that it is warm, not hot, before the baby goes in

Why this is the answer

Bath water should be comfortably warm, about 37 °C (98.6 °F), checked with a thermometer or the elbow, and the baby is never left alone, even in shallow water. Plain water or a mild baby cleanser is used. Some guidance, such as in the US, advises sponge baths until the cord stump has fallen off.

Answer

D · Check that it is warm, not hot, before the baby goes in
2.Maternity & obstetric nursing

Answer: C · Acute bilirubin encephalopathy

Why this is the answer

Lethargy, poor feeding, hypertonia with arching and a high-pitched cry are signs of acute bilirubin encephalopathy. An urgent exchange transfusion may be needed to prevent permanent kernicterus.

Answer

C · Acute bilirubin encephalopathy
3.Dosage calculations

Answer: V = 1.8 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 = 5·18 = 90 mg

Volume

V = 90/50 = 1.8 mL

On the syringe

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

Answer

V = 1.8 mL
4.Dosage calculations

Answer: D = 169.9 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 = √(165·63/3600) = √2.888 = 1.699 m²

Dose

D = 100·1.699 = 169.9 mg

Answer

D = 169.9 mg
5.IV infusion rates

Answer: R = 10 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.

Millilitres per minute

40/60 = 0.6667 mL/min

Drip rate

R = 0.6667·15 = 10 gtt/min

Answer

R = 10 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

500/500 = 1 mg/mL

Dose rate

D = 1·10 = 10 mg/h

Answer

D = 10 mg/h

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