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 baby girl has a small amount of blood-tinged vaginal discharge on day 3. What should the nurse tell the parents?

  1. AIt means the baby has a bleeding disorder
  2. BIt shows a urinary tract infection
  3. CIt is a sign of sexual abuse
  4. DIt is caused by maternal hormones
2.Maternity & obstetric nursingHard

A woman with gestational diabetes was on insulin during pregnancy. What change in her insulin needs is expected right after birth?

  1. AShe will need lifelong insulin
  2. BThey double because of the stress of birth, so the insulin dose is increased
  3. CThey fall quickly, so glucose is monitored and insulin is often stopped
  4. DThey stay the same for 6 weeks
3.Dosage calculationsMedium
81 kgBSA = 1.7 m²50 mg/m²D = ? mg

A patient weighing 81 kg has a body surface area of 1.7 m². The prescription is 50 mg/m². Find the dose D in mg.

81 kgBSA = 1.7 m²50 mg/m²
D = mg
4.Dosage calculationsHard
40k units250 mL? mL/h500 units/h

An infusion contains 40000 units of a drug in 250 mL. The prescription is 500 units per hour. At what rate R do you set the pump, in mL/h?

40000 units/250 mL500 units/h
R = mL/h
5.IV infusion ratesMedium
V = ?60 gtt/mL50 gtt/min6 h

A drip runs at 50 gtt/min through a set of 60 gtt/mL. How many millilitres V does the patient receive in 6 hours?

50 gtt/min60 gtt/mL6 h
V = mL
6.IV infusion ratesHard
100 mg250 mL15 mL/h? mcg/min

An infusion of 100 mg in 250 mL runs at 15 mL/h. How many micrograms per minute D does the patient receive?

100 mg/250 mL15 mL/h
D = mcg/min

3Solutions

1.Maternity & obstetric nursing

Answer: D · It is caused by maternal hormones

Why this is the answer

Pseudomenstruation is caused by withdrawal of maternal hormones after birth and resolves within days. Swollen breasts in either sex have the same cause.

Answer

D · It is caused by maternal hormones
2.Maternity & obstetric nursing

Answer: C · They fall quickly, so glucose is monitored and insulin is often stopped

Why this is the answer

The placenta produced the hormones that caused insulin resistance. After birth, glucose usually returns to normal, so insulin is often stopped and glucose is checked. She needs a glucose test some weeks after birth and long-term screening for type 2 diabetes.

Answer

C · They fall quickly, so glucose is monitored and insulin is often stopped
3.Dosage calculations

Answer: D = 85 mg

Body-surface-area dosing: many cytotoxic and some paediatric doses are prescribed per square metre of body surface area: dose (mg) = dose per m² × BSA (m²). The Mosteller formula estimates BSA = √(height (cm) × weight (kg)/3600).

Dose

D = 50·1.7 = 85 mg

Answer

D = 85 mg
4.Dosage calculations

Answer: R = 3.125 mL/h

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.

Concentration

40000/250 = 160 units/mL

Pump rate

R = 500/160 = 3.125 mL/h

Answer

R = 3.125 mL/h
5.IV infusion rates

Answer: V = 300 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

50·60/60 = 50 mL/h

Volume

V = 50·6 = 300 mL

Answer

V = 300 mL
6.IV infusion rates

Answer: D = 100 mcg/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

100000 mcg/250 mL = 400 mcg/mL

Dose per hour

15·400 = 6000 mcg/h

Dose per minute

D = 6000/60 = 100 mcg/min

Answer

D = 100 mcg/min

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