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 an indwelling catheter placed before a caesarean birth?

  1. ATo measure the baby's fluid balance
  2. BTo collect a urine sample for culture
  3. CTo prevent postpartum haemorrhage
  4. DTo keep the bladder empty during surgery
2.Maternity & obstetric nursingHard

A multiparous woman arrives with strong contractions and the baby is born within an hour of their onset. What should the nurse monitor closely afterwards?

  1. AOnly the mother's temperature
  2. BUterine tone, bleeding and newborn injury
  3. CThe mother's ability to walk alone
  4. DOnly the newborn's blood glucose
3.Dosage calculationsMedium
45 kg20 mg/kg/day2× per dayD = ? mg

A patient weighs 45 kg. The prescribed dose is 20 mg/kg per day, given in 2 equal doses. How many milligrams D are given per dose?

45 kg20 mg/kg/day2× per day
D = mg
4.Dosage calculationsHard
25%stockwater = ? mL

You must prepare 100 mL of a 2.5% (w/v) solution from a 25% (w/v) stock solution. How much water W must be added to the stock?

C₁ = 25%C₂ = 2.5%V₂ = 100 mL
W = mL
5.IV infusion ratesMedium
1260 mLleft? mL/h4 h left

1500 mL was ordered over 6 hours. After 2 hours you find that 1260 mL is still in the bag, and the order must still finish on time. To what rate R in mL/h must the pump be reset?

1500 mL / 6 hafter 2 h: 1260 mL
R = mL/h
6.IV infusion ratesHard
250 mg250 mL10 mL/h? mg/h

A bag contains 250 mg of a drug in 250 mL and runs at 10 mL/h. How many milligrams per hour D does the patient receive?

250 mg/250 mL10 mL/h
D = mg/h

3Solutions

1.Maternity & obstetric nursing

Answer: D · To keep the bladder empty during surgery

Why this is the answer

An empty bladder reduces the risk of bladder injury during surgery and allows urine output to be monitored. It is usually removed once the woman can walk.

Answer

D · To keep the bladder empty during surgery
2.Maternity & obstetric nursing

Answer: B · Uterine tone, bleeding and newborn injury

Why this is the answer

Precipitous labour increases the risk of cervical and perineal tears, uterine atony and haemorrhage, and of newborn injuries such as bruising or intracranial bleeding.

Answer

B · Uterine tone, bleeding and newborn injury
3.Dosage calculations

Answer: D = 450 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

20·45 = 900 mg

Per dose

D = 900/2 = 450 mg

Answer

D = 450 mg
4.Dosage calculations

Answer: W = 90 mL

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.

Volume of stock

V₁ = 2.5·100/25 = 10 mL

Water to add

W = 100 − 10 = 90 mL

Answer

W = 90 mL
5.IV infusion rates

Answer: R = 315 mL/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.

Original rate

1500/6 = 250 mL/h

New rate

R = 1260/4 = 315 mL/h

Answer

R = 315 mL/h

This is more than a 25% increase: most hospitals require you to contact the prescriber instead of catching up, and to assess the patient for fluid overload.

6.IV infusion rates

Answer: D = 10 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

250/250 = 1 mg/mL

Dose rate

D = 1·10 = 10 mg/h

Answer

D = 10 mg/h

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