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 who has had a caesarean asks when she can drive again. Which answer is most accurate?

  1. AOnly after her stitches are removed by a doctor
  2. BNever before 6 months
  3. CWhen she can brake hard without pain
  4. DThe same day she is discharged
2.Maternity & obstetric nursingHard

A biophysical profile scores 4 out of 10 at 38 weeks. How should the nurse interpret this?

  1. AIt is equivocal and should be repeated next week
  2. BIt only means the woman needs to drink more water
  3. CIt is abnormal and needs prompt review
  4. DIt is normal and reassuring
3.Dosage calculationsMedium
70 kg7.5 mg/kg/day4× per dayD = ? mg

A patient weighs 70 kg. The prescribed dose is 7.5 mg/kg per day, given in 4 equal doses. How many milligrams D are given per dose?

70 kg7.5 mg/kg/day4× per day
D = mg
4.Dosage calculationsHard
20%stockV₁ = ? mL

You must prepare 500 mL of a 5% (w/v) solution from a 20% (w/v) stock solution. What volume of stock V₁ do you need?

C₁ = 20%C₂ = 5%V₂ = 500 mL
V₁ = mL
5.IV infusion ratesMedium
500 mL15 gtt/mL12 h? gtt/min

Infuse 500 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.

500 mL12 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
800 mLleft? mL/h4 h left

1000 mL was ordered over 6 hours. After 2 hours you find that 800 mL is still in the bag, and the order must still finish on time. By what percentage Δ must the original pump rate be increased?

1000 mL / 6 hafter 2 h: 800 mL
Δ = %

3Solutions

1.Maternity & obstetric nursing

Answer: C · When she can brake hard without pain

Why this is the answer

There is no fixed time. She can drive when she can brake suddenly, look over her shoulder and wear a seat belt comfortably. Many women need about 4 to 6 weeks, and insurance rules may apply.

Answer

C · When she can brake hard without pain
2.Maternity & obstetric nursing

Answer: C · It is abnormal and needs prompt review

Why this is the answer

A score of 8 to 10 is normal, 6 is equivocal, and 4 or less is abnormal and suggests fetal hypoxia. At term, a low score usually leads to prompt review and consideration of birth.

Answer

C · It is abnormal and needs prompt review
3.Dosage calculations

Answer: D = 131.3 mg

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.

Total per day

7.5·70 = 525 mg

Per dose

D = 525/4 = 131.3 mg

Answer

D = 131.3 mg
4.Dosage calculations

Answer: V₁ = 125 mL

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.

Volume of stock

V₁ = 5·500/20 = 125 mL

Answer

V₁ = 125 mL
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.

Time in minutes

12·60 = 720 min

Drip rate

R = 500·15/720 = 10.42 ≈ 10 gtt/min

Answer

R = 10 gtt/min

At the bedside you round to the nearest whole drop: 10 gtt/min.

6.IV infusion rates

Answer: Δ = 20 %

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.

Original rate

1000/6 = 166.7 mL/h

New rate

R = 800/4 = 200 mL/h

Percentage change

Δ = (200 − 166.7)/166.7·100% = 20%

Answer

Δ = 20%

Many hospitals allow such an adjustment up to 25% without a new order; check local policy.

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