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 finding in a term newborn's first hours is normal?

  1. AA respiratory rate of 80 at rest with retractions
  2. BPauses in breathing of 30 seconds with bradycardia
  3. CCentral cyanosis of the lips and tongue
  4. DShort breathing pauses with no colour change
2.Maternity & obstetric nursingHard

A woman has cytomegalovirus (CMV) infection in pregnancy. Which outcome in the baby is a major concern?

  1. AClubfoot only
  2. BHearing loss and developmental delay
  3. COpen neural tube defects such as spina bifida
  4. DPhenylketonuria
3.Dosage calculationsMedium
1:10 000ampouleV = ? mL

A prefilled syringe of epinephrine (adrenaline) is labelled 1:10 000 (0.1 mg/mL). The prescription is 1 mg IV in cardiac arrest. What volume V do you give?

1:10 0001 mg
V = mL
4.Dosage calculationsHard
00.10.20.30.40.50.60.70.80.911 mL

The prescription is 465 micrograms. The ampoule contains 0.5 mg/mL. Draw up the dose in the 1 mL syringe: what volume V do you give?

465 mcg0.5 mg/mL
V = mL
5.IV infusion ratesMedium
1000 mL15 gtt/mL5 h? gtt/min

Infuse 1000 mL over 5 hours with a giving set of 15 gtt/mL. Find the drip rate R in drops per minute.

1000 mL5 h15 gtt/mL
R = gtt/min
6.IV infusion ratesHard
100 mg100 mL15 gtt/mL40 mg/h? gtt/min

100 mg of a drug is diluted in 100 mL and given by gravity through a set of 15 gtt/mL. The order is 40 mg per hour. Find the drip rate R in drops per minute.

100 mg/100 mL40 mg/h15 gtt/mL
R = gtt/min

3Solutions

1.Maternity & obstetric nursing

Answer: D · Short breathing pauses with no colour change

Why this is the answer

Newborns breathe irregularly, with short pauses of a few seconds and no change in colour or heart rate. Apnoea of 20 seconds or more, or any pause with cyanosis or bradycardia, is abnormal.

Answer

D · Short breathing pauses with no colour change
2.Maternity & obstetric nursing

Answer: B · Hearing loss and developmental delay

Why this is the answer

Congenital CMV is a leading cause of non-genetic sensorineural hearing loss and can cause microcephaly and developmental delay. Hand hygiene after contact with young children's saliva and urine reduces the risk.

Answer

B · Hearing loss and developmental delay
3.Dosage calculations

Answer: V = 10 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

1:10 000 = 1 g/10000 mL = 0.1 mg/mL

Volume

V = 1/0.1 = 10 mL

Answer

V = 10 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 = 0.93 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

0.5 mg/mL = 500 mcg/mL

Volume

V = 465/500 = 0.93 mL

Answer

V = 0.93 mL
5.IV infusion rates

Answer: R = 50 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

5·60 = 300 min

Drip rate

R = 1000·15/300 = 50 gtt/min

Answer

R = 50 gtt/min
6.IV infusion rates

Answer: R = 10 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

100/100 = 1 mg/mL

Volume per hour

40/1 = 40 mL/h

Drip rate

R = 40·15/60 = 10 gtt/min

Answer

R = 10 gtt/min

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