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 10 weeks has morning sickness. Which suggestion is most likely to help?

  1. ADrink large amounts of fluid with each meal
  2. BEat dry crackers before rising and eat small meals
  3. CSkip breakfast and eat one large meal in the evening
  4. DEat spicy and fatty foods to settle the stomach
2.Maternity & obstetric nursingHard

Why does the foramen ovale close soon after birth?

  1. AThe umbilical vein carries more blood to the heart
  2. BProstaglandin levels rise in the newborn's blood
  3. CLeft atrial pressure rises above right atrial pressure
  4. DBlood flow to the lungs decreases after birth
3.Dosage calculationsMedium
80 kgBSA = 1.77 m²75 mg/m²D = ? mg

A patient weighing 80 kg has a body surface area of 1.77 m². The prescription is 75 mg/m². Find the dose D in mg.

80 kgBSA = 1.77 m²75 mg/m²
D = mg
4.Dosage calculationsHard
25k units500 mL? mL/h1200 units/h

An infusion contains 25000 units of a drug in 500 mL. The prescription is 1200 units per hour. At what rate R do you set the pump, in mL/h?

25000 units/500 mL1200 units/h
R = mL/h
5.IV infusion ratesMedium
1000 mL15 gtt/mL12 h? gtt/min

Infuse 1000 mL over 12 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1000 mL12 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
1000 mg250 mL15 mL/h? mg/h

A bag contains 1000 mg of a drug in 250 mL and runs at 15 mL/h. How many milligrams per hour D does the patient receive?

1000 mg/250 mL15 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: B · Eat dry crackers before rising and eat small meals

Why this is the answer

Eating something dry before rising, small frequent meals, and drinking fluids between rather than with meals reduce nausea. Fatty and spicy foods tend to worsen it.

Answer

B · Eat dry crackers before rising and eat small meals
2.Maternity & obstetric nursing

Answer: C · Left atrial pressure rises above right atrial pressure

Why this is the answer

With the first breaths, pulmonary resistance falls and more blood returns to the left atrium, while cord clamping lowers right-sided pressure. The higher left atrial pressure pushes the flap of the foramen ovale shut.

Answer

C · Left atrial pressure rises above right atrial pressure
3.Dosage calculations

Answer: D = 132.8 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).

Dose

D = 75·1.77 = 132.8 mg

Answer

D = 132.8 mg
4.Dosage calculations

Answer: R = 24 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.

Concentration

25000/500 = 50 units/mL

Pump rate

R = 1200/50 = 24 mL/h

Answer

R = 24 mL/h
5.IV infusion rates

Answer: R = 21 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

12·60 = 720 min

Drip rate

R = 1000·15/720 = 20.83 ≈ 21 gtt/min

Answer

R = 21 gtt/min

At the bedside you round to the nearest whole drop: 21 gtt/min.

6.IV infusion rates

Answer: D = 60 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

1000/250 = 4 mg/mL

Dose rate

D = 4·15 = 60 mg/h

Answer

D = 60 mg/h

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