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 pregnant woman taking iron says her stools have turned black. What is the best response?

  1. AExplain that this is an expected effect of iron
  2. BAdvise her to go to the emergency department now
  3. CTell her to double the dose of the tablets
  4. DTell her to stop the iron immediately
2.Maternity & obstetric nursingHard

Which statement by a pregnant woman with gestational diabetes shows she understands her care?

  1. A"I will check my glucose as shown and record it."
  2. B"My baby's growth will not need monitoring."
  3. C"I can skip meals if my glucose is high in the morning."
  4. D"Insulin will harm my baby, so I will refuse it."
3.Dosage calculationsMedium
45 kg5 mg/kg/day2× per dayD = ? mg

A patient weighs 45 kg. The prescribed dose is 5 mg/kg per day, given in 2 equal doses. How many milligrams D are given per dose?

45 kg5 mg/kg/day2× per day
D = mg
4.Dosage calculationsHard
40 mg/1 mLV = ? mL

A child weighing 20 kg is prescribed 20 mg/kg per dose of an oral suspension that contains 40 mg in 1 mL. What volume V do you give?

20 kg20 mg/kg40 mg/1 mL
V = mL
5.IV infusion ratesMedium
1500 mL10 gtt/mL10 h? gtt/min

Infuse 1500 mL over 10 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute.

1500 mL10 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
1 g250 mL? mL/h4 mg/min

A bag contains 1 g of a drug in 250 mL. The order is 4 mg per minute. At what rate R do you set the pump, in mL/h?

1 g/250 mL4 mg/min
R = mL/h

3Solutions

1.Maternity & obstetric nursing

Answer: A · Explain that this is an expected effect of iron

Why this is the answer

Iron supplements commonly make stools dark green or black. This is harmless, unlike tarry stools with signs of bleeding such as dizziness.

Answer

A · Explain that this is an expected effect of iron
2.Maternity & obstetric nursing

Answer: A · "I will check my glucose as shown and record it."

Why this is the answer

Regular glucose monitoring with records guides treatment changes. Skipping meals can cause hypoglycaemia and ketosis, insulin does not cross the placenta in a meaningful amount, and fetal growth is monitored.

Answer

A · "I will check my glucose as shown and record it."
3.Dosage calculations

Answer: D = 112.5 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.

Total per day

5·45 = 225 mg

Per dose

D = 225/2 = 112.5 mg

Answer

D = 112.5 mg
4.Dosage calculations

Answer: V = 10 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.

Dose from weight

20·20 = 400 mg

Volume

V = (400/40)·1 = 10 mL

Answer

V = 10 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.

Time in minutes

10·60 = 600 min

Drip rate

R = 1500·10/600 = 25 gtt/min

Answer

R = 25 gtt/min
6.IV infusion rates

Answer: R = 60 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

1000 mg/250 mL = 4 mg/mL

Dose per hour

4·60 = 240 mg/h

Pump rate

R = 240/4 = 60 mL/h

Answer

R = 60 mL/h

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