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

Which is the correct order of the first cardinal movements of labour?

  1. ADescent, extension, engagement, flexion, internal rotation
  2. BInternal rotation, engagement, descent, extension, flexion
  3. CFlexion, engagement, extension, descent, internal rotation
  4. DEngagement, descent, flexion, internal rotation, extension
2.Maternity & obstetric nursingHard

A labouring woman feels intense rectal pressure and says "the baby is coming". She was 7 cm 20 minutes ago. What should the nurse do first?

  1. AGive her an opioid for the pain
  2. BTell her it is too early and to stop pushing
  3. CLeave her to get the birth equipment from the store
  4. DCheck whether the head is visible and stay with her
3.Dosage calculationsMedium
1:1000ampouleV = ? mL

An ampoule of epinephrine (adrenaline) is labelled 1:1000 (1 mg/mL). The prescription is 0.3 mg IM for anaphylaxis. What volume V do you draw up?

1:10000.3 mg
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 0.15 mg. The ampoule contains 1000 micrograms per mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

0.15 mg1000 mcg/mL
V = mL
5.IV infusion ratesMedium
V = ?60 gtt/mL40 gtt/min8 h

A drip runs at 40 gtt/min through a set of 60 gtt/mL. How many millilitres V does the patient receive in 8 hours?

40 gtt/min60 gtt/mL8 h
V = mL
6.IV infusion ratesHard
1 g250 mL? mL/h3 mg/min

A bag contains 1 g of a drug in 250 mL. The order is 3 mg per minute. At what rate R do you set the pump, in mL/h?

1 g/250 mL3 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: D · Engagement, descent, flexion, internal rotation, extension

Why this is the answer

The cardinal movements are engagement, descent, flexion, internal rotation, extension, external rotation (restitution) and expulsion.

Answer

D · Engagement, descent, flexion, internal rotation, extension
2.Maternity & obstetric nursing

Answer: D · Check whether the head is visible and stay with her

Why this is the answer

A strong urge to push and rectal pressure suggest full dilation or imminent birth. The nurse stays, checks for crowning, calls for help and prepares for birth. Opioids close to birth can depress the newborn's breathing.

Answer

D · Check whether the head is visible and stay with her
3.Dosage calculations

Answer: V = 0.3 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.

Concentration

1:1000 = 1 g/1000 mL = 1 mg/mL

Volume

V = 0.3/1 = 0.3 mL

Answer

V = 0.3 mL

US labels now state mg/mL (1 mg/mL = 1:1000; 0.1 mg/mL = 1:10 000). Never give 1 mg/mL epinephrine IV push.

4.Dosage calculations

Answer: V = 0.15 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

0.15 mg = 150 mcg

Volume

V = 150/1000 = 0.15 mL

Answer

V = 0.15 mL
5.IV infusion rates

Answer: V = 320 mL

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.

Rate in mL/h

40·60/60 = 40 mL/h

Volume

V = 40·8 = 320 mL

Answer

V = 320 mL
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

1000 mg/250 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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