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

An Rh-negative woman has just given birth to an Rh-positive baby. When should anti-D immunoglobulin be given?

  1. AWithin 72 hours of birth
  2. BBefore the next pregnancy only
  3. CWithin 2 weeks of birth
  4. DOnly if the baby develops jaundice
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. AThey stay the same for 6 weeks
  2. BShe will need lifelong insulin
  3. CThey double because of the stress of birth, so the insulin dose is increased
  4. DThey fall quickly, so glucose is monitored and insulin is often stopped
3.Dosage calculationsMedium
10%100 mLm = ? mg

How many milligrams of drug m are in 100 mL of a 10% (w/v) solution?

10% w/v100 mL
m = mg
4.Dosage calculationsHard
200 mg/5 mLV = ? mL

A child weighing 8 kg is prescribed 5 mg/kg per dose of an oral suspension that contains 200 mg in 5 mL. What volume V do you give?

8 kg5 mg/kg200 mg/5 mL
V = mL
5.IV infusion ratesMedium
250 mL10 gtt/mL4 h? gtt/min

Infuse 250 mL over 4 hours with a giving set of 10 gtt/mL. Find the drip rate R in drops per minute. Round to the nearest whole number.

250 mL4 h10 gtt/mL
R = gtt/min
6.IV infusion ratesHard
200 mg100 mL25 mL/h? mg/h

A bag contains 200 mg of a drug in 100 mL and runs at 25 mL/h. How many milligrams per hour D does the patient receive?

200 mg/100 mL25 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: A · Within 72 hours of birth

Why this is the answer

Anti-D is given within 72 hours of the birth of an Rh-positive baby, after a test confirms the mother is not already sensitised. It is not needed if the baby is Rh-negative.

Answer

A · Within 72 hours of birth
2.Maternity & obstetric nursing

Answer: D · 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

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

Answer: m = 10000 mg

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

10% = 10 g/100 mL = 100 mg/mL

Mass of drug

m = 100·100 = 10000 mg

Answer

m = 10000 mg
4.Dosage calculations

Answer: V = 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.

Dose from weight

5·8 = 40 mg

Volume

V = (40/200)·5 = 1 mL

Answer

V = 1 mL
5.IV infusion rates

Answer: R = 10 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

4·60 = 240 min

Drip rate

R = 250·10/240 = 10.42 ≈ 10 gtt/min

Answer

R = 10 gtt/min

At the bedside you round to the nearest whole drop: 10 gtt/min.

6.IV infusion rates

Answer: D = 50 mg/h

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.

Concentration

200/100 = 2 mg/mL

Dose rate

D = 2·25 = 50 mg/h

Answer

D = 50 mg/h

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