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

Contractions start at 10:00, 10:04 and 10:08, and each lasts 60 seconds. How should the nurse describe them?

  1. AEvery 4 minutes, lasting 240 seconds
  2. BEvery 3 minutes, lasting 60 seconds
  3. CEvery 4 minutes, lasting 60 seconds
  4. DEvery 5 minutes, lasting 60 seconds
2.Maternity & obstetric nursingHard

A woman with known mitral stenosis is pregnant. When is she at greatest risk of heart failure?

  1. AWhen blood volume peaks in late pregnancy and in the hours after birth
  2. BOnly in the first trimester, when nausea is worst
  3. COnly during the first stage of labour
  4. DRisk is the same at every point in pregnancy
3.Dosage calculationsMedium
80 kg5 mg/kg/day4× per dayD = ? mg

A patient weighs 80 kg. The prescribed dose is 5 mg/kg per day, given in 4 equal doses. How many milligrams D are given per dose?

80 kg5 mg/kg/day4× per day
D = mg
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 0.34 mg. The ampoule contains 1000 micrograms per mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

0.34 mg1000 mcg/mL
V = mL
5.IV infusion ratesMedium
1000 mL10 gtt/mL2 h? gtt/min

Infuse 1000 mL over 2 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

1000 mL2 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
2 g500 mL? mL/h3 mg/min

A bag contains 2 g of a drug in 500 mL. The order is 3 mg per minute. At what rate R do you set the pump, in mL/h?

2 g/500 mL3 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: C · Every 4 minutes, lasting 60 seconds

Why this is the answer

Frequency is measured from the start of one contraction to the start of the next (4 minutes), and duration from the start to the end of the same contraction (60 seconds). The 3 minutes between contractions is the resting interval.

Answer

C · Every 4 minutes, lasting 60 seconds
2.Maternity & obstetric nursing

Answer: A · When blood volume peaks in late pregnancy and in the hours after birth

Why this is the answer

Cardiac decompensation is most likely when blood volume peaks in the late second and third trimester and right after birth, when blood from the contracted uterus returns to the circulation. These women need close monitoring postpartum.

Answer

A · When blood volume peaks in late pregnancy and in the hours after birth
3.Dosage calculations

Answer: D = 100 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

5·80 = 400 mg

Per dose

D = 400/4 = 100 mg

Answer

D = 100 mg
4.Dosage calculations

Answer: V = 0.34 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

0.34 mg = 340 mcg

Volume

V = 340/1000 = 0.34 mL

Answer

V = 0.34 mL
5.IV infusion rates

Answer: R = 83 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

2·60 = 120 min

Drip rate

R = 1000·10/120 = 83.33 ≈ 83 gtt/min

Answer

R = 83 gtt/min

At the bedside you round to the nearest whole drop: 83 gtt/min.

6.IV infusion rates

Answer: R = 45 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/500 mL = 4 mg/mL

Dose per hour

3·60 = 180 mg/h

Pump rate

R = 180/4 = 45 mL/h

Answer

R = 45 mL/h

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