calculation skills Flashcards
What does the Calculation Skills section of the PSA assess?
Ability to accurately calculate drug doses, adjust doses based on patient factors, calculate infusion rates and fluid requirements, convert between different units of measurement.
What is the formula for calculating drug dosage based on weight?
mg/kg.
What are some factors that might require dose adjustments?
- Renal impairment
- Hepatic impairment.
What is an example of a maximum dose limit in medication?
Paracetamol and opioids.
How much paracetamol should be prescribed for a child weighing 20kg at a dose of 15mg/kg every 6 hours?
300mg every 6 hours.
What is the unit of measurement for IV infusion rates?
mL/hour or mL/min.
How do you convert mcg to mg?
5 mcg = 0.005 mg.
What is the infusion rate for a 70kg patient requiring dopamine at 5mcg/kg/min with a concentration of 200mg in 50mL?
5.25mL/hour.
What is the standard calculation for daily maintenance fluids for adults?
- 25–30mL/kg/day of water
- 1 mmol/kg/day of sodium, potassium, chloride
- 50–100g/day of glucose.
What volume of fluid should be given per day to a 60kg adult?
1.8L/day of fluids.
How do you calculate the volume to administer for lorazepam 2mg IV when the ampoule contains 4mg in 1mL?
0.5mL.
What is the relationship between mcg and mg?
1mg = 1000mcg.
What is the Cockcroft-Gault formula for creatinine clearance?
CrCl = ((140 - age) × weight (kg) × 1.23) / serum creatinine (µmol/L).
What adjustment should be made to the Cockcroft-Gault formula for females?
Multiply by 0.85.
What are some high-yield calculation tips for the PSA?
- Check units in the question and answer
- Round sensibly
- Use common sense
- Use the BNF for dose ranges
- Practice under timed conditions.
Fill in the blank: Always double-check ______ in the question.
units.
True or False: It is acceptable to use excessive decimal places in calculations.
False.
Fill in the blank: A maintenance fluid rate of 500mL/hour is clearly too ______.
high.
