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

Progesterone relaxes smooth muscle in pregnancy. Which common complaint does this help explain?

  1. ANasal stuffiness
  2. BIncreased appetite
  3. CConstipation
  4. DGum bleeding
2.Maternity & obstetric nursingHard

A large for gestational age newborn of a mother with diabetes is also very red and has a high haematocrit. Which complication of this finding should the nurse watch for?

  1. AJaundice
  2. BDehydration caused by vomiting
  3. CNeural tube defects
  4. DHypothermia caused by sweating
3.Dosage calculationsMedium
024681010 mL

A child weighing 12 kg is prescribed 4 mg/kg of a drug. The stock solution contains 20 mg/mL. Draw up the dose: what volume V do you give?

12 kg4 mg/kg20 mg/mL
V = mL
4.Dosage calculationsHard
40k units250 mL? mL/h1500 units/h

An infusion contains 40000 units of a drug in 250 mL. The prescription is 1500 units per hour. At what rate R do you set the pump, in mL/h?

40000 units/250 mL1500 units/h
R = mL/h
5.IV infusion ratesMedium
250 mL60 gtt/mL5 h? gtt/min

Infuse 250 mL over 5 hours with a giving set of 60 gtt/mL. Find the drip rate R in drops per minute.

250 mL5 h60 gtt/mL
R = gtt/min
6.IV infusion ratesHard
250 mg250 mL60 gtt/mL60 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 60 mg per hour. Find the drip rate R in drops per minute.

250 mg/250 mL60 mg/h60 gtt/mL
R = gtt/min

3Solutions

1.Maternity & obstetric nursing

Answer: C · Constipation

Why this is the answer

Progesterone slows gut motility, which causes constipation and contributes to heartburn because the lower oesophageal sphincter relaxes. Gum bleeding and nasal stuffiness are mainly due to oestrogen and increased blood flow.

Answer

C · Constipation
2.Maternity & obstetric nursing

Answer: A · Jaundice

Why this is the answer

Polycythaemia is common in infants of diabetic mothers and SGA babies. Breakdown of the extra red cells raises bilirubin, and high viscosity can cause poor feeding, lethargy or thrombosis.

Answer

A · Jaundice
3.Dosage calculations

Answer: V = 2.4 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 = 4·12 = 48 mg

Volume

V = 48/20 = 2.4 mL

On the syringe

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

Answer

V = 2.4 mL
4.Dosage calculations

Answer: R = 9.375 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 = 1500/160 = 9.375 mL/h

Answer

R = 9.375 mL/h
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 = 250·60/300 = 50 gtt/min

Answer

R = 50 gtt/min
6.IV infusion rates

Answer: R = 60 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

60/1 = 60 mL/h

Drip rate

R = 60·60/60 = 60 gtt/min

Answer

R = 60 gtt/min

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