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 newborn appears jaundiced at 18 hours of age. What does this suggest?

  1. ANormal physiological jaundice that needs no further action
  2. BPathological jaundice that needs prompt assessment
  3. CA normal effect of vitamin K
  4. DBreast milk jaundice
2.Maternity & obstetric nursingHard

Just after the membranes rupture, there is painless vaginal bleeding and the fetal heart rate drops sharply. The mother's vital signs are normal. Which condition is most likely?

  1. AUterine rupture
  2. BPlacental abruption
  3. CBloody show
  4. DRuptured vasa praevia
3.Dosage calculationsMedium
22 kg20 mg/kgD = ? mg

A patient weighs 22 kg and is prescribed 20 mg/kg as a single dose. Find the dose D in mg.

22 kg20 mg/kg
D = mg
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 830 micrograms. The ampoule contains 1 mg/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

830 mcg1 mg/mL
V = mL
5.IV infusion ratesMedium
500 mL20 gtt/mL4 h? gtt/min

Infuse 500 mL over 4 hours with a giving set of 20 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

500 mL4 h20 gtt/mL
R = gtt/min
6.IV infusion ratesHard
250 mg250 mL60 gtt/mL20 mg/h? gtt/min

250 mg of a drug is diluted in 250 mL and given by gravity through a set of 60 gtt/mL. The order is 20 mg per hour. Find the drip rate R in drops per minute.

250 mg/250 mL20 mg/h60 gtt/mL
R = gtt/min

3Solutions

1.Maternity & obstetric nursing

Answer: B · Pathological jaundice that needs prompt assessment

Why this is the answer

Physiological jaundice usually appears after 24 hours. Jaundice in the first 24 hours suggests haemolysis (for example blood group incompatibility) or infection and needs a bilirubin level and medical review.

Answer

B · Pathological jaundice that needs prompt assessment
2.Maternity & obstetric nursing

Answer: D · Ruptured vasa praevia

Why this is the answer

Rupture of the membranes can tear unprotected fetal vessels in vasa praevia. Fetal blood loss causes rapid bradycardia while the mother stays stable. An emergency caesarean is needed.

Answer

D · Ruptured vasa praevia
3.Dosage calculations

Answer: D = 440 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.

Dose

20·22 = 440 mg

Answer

D = 440 mg
4.Dosage calculations

Answer: V = 0.83 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

1 mg/mL = 1000 mcg/mL

Volume

V = 830/1000 = 0.83 mL

Answer

V = 0.83 mL
5.IV infusion rates

Answer: R = 42 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

4·60 = 240 min

Drip rate

R = 500·20/240 = 41.67 ≈ 42 gtt/min

Answer

R = 42 gtt/min

At the bedside you round to the nearest whole drop: 42 gtt/min.

6.IV infusion rates

Answer: R = 20 gtt/min

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

250/250 = 1 mg/mL

Volume per hour

20/1 = 20 mL/h

Drip rate

R = 20·60/60 = 20 gtt/min

Answer

R = 20 gtt/min

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