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

Why is a copper intrauterine device a good contraceptive option for many breastfeeding mothers?

  1. AIt must be replaced every month
  2. BIt protects against sexually transmitted infections
  3. CIt is hormone-free and very effective
  4. DIt increases milk production
2.Maternity & obstetric nursingHard

Fluid leaking from the vagina is tested. Which result supports rupture of the membranes?

  1. AFluid that smells of ammonia
  2. BA nitrazine test that turns yellow, showing acidic fluid
  3. CA ferning pattern on a dried slide under the microscope
  4. DFluid that contains glucose on a urine dipstick
3.Dosage calculationsMedium
024681010 mL

A child weighing 16 kg is prescribed 7.5 mg/kg of a drug. The stock solution contains 25 mg/mL. Draw up the dose: what volume V do you give?

16 kg7.5 mg/kg25 mg/mL
V = mL
4.Dosage calculationsHard
100 mg/1 mLV = ? mL

A patient weighs 74.8 lb. The prescription is 15 mg/kg as a single dose, and the stock contains 100 mg in 1 mL. Using 1 kg = 2.2 lb, what volume V do you give?

74.8 lb15 mg/kg100 mg/1 mL1 kg = 2.2 lb
V = mL
5.IV infusion ratesMedium
60 gtt/mL25 mL/h? gtt/min

An infusion is ordered at 25 mL/h, but no pump is available. It runs by gravity through a giving set of 60 gtt/mL. Find the drip rate R in drops per minute.

25 mL/h60 gtt/mL
R = gtt/min
6.IV infusion ratesHard
2 g500 mL? mL/h1.5 mg/min

A bag contains 2 g of a drug in 500 mL. The order is 1.5 mg per minute. At what rate R do you set the pump, in mL/h?

2 g/500 mL1.5 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: C · It is hormone-free and very effective

Why this is the answer

The copper IUD contains no hormones, does not affect milk supply and is highly effective for many years. It does not protect against sexually transmitted infections.

Answer

C · It is hormone-free and very effective
2.Maternity & obstetric nursing

Answer: C · A ferning pattern on a dried slide under the microscope

Why this is the answer

Amniotic fluid forms a fern-like pattern when dried and turns nitrazine paper blue because it is alkaline. Vaginal secretions and urine are usually acidic. Blood, semen and infection can give false positives on nitrazine testing.

Answer

C · A ferning pattern on a dried slide under the microscope
3.Dosage calculations

Answer: V = 4.8 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.

Dose from body weight

D = 7.5·16 = 120 mg

Volume

V = 120/25 = 4.8 mL

On the syringe

On this 10 mL syringe every small line is 0.2 mL.

Answer

V = 4.8 mL
4.Dosage calculations

Answer: V = 5.1 mL

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.

Weight in kg

74.8/2.2 = 34 kg

Dose

15·34 = 510 mg

Volume

V = (510/100)·1 = 5.1 mL

Answer

V = 5.1 mL
5.IV infusion rates

Answer: R = 25 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.

Millilitres per minute

25/60 = 0.4167 mL/min

Drip rate

R = 0.4167·60 = 25 gtt/min

Answer

R = 25 gtt/min

With a microdrip set (60 gtt/mL), gtt/min equals mL/h.

6.IV infusion rates

Answer: R = 22.5 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

1.5·60 = 90 mg/h

Pump rate

R = 90/4 = 22.5 mL/h

Answer

R = 22.5 mL/h

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