Calculations IV Flashcards
(12 cards)
What is the calculation for BMI?
metric: weight (kg) / (height [m])^2
not-metric: [ weight (lb) / (height [in])^2 ] x703
What is the BMI range for normal weight?
18.5-24.9
What 4 medication calculations should you use IBW for, regardless of if they are normal weight or overweight?
- aminophylline
- theophylline
- acyclovir
- levothyroxine
If the patient is overweight (TBW ≥ 120% of IBW), what 3 medications should you still use TBW for? What medication should you use AdjBW for?
if TBW ≥ 120% IBW
TBW:
- LMWHs
- UFH
- vancomycin
AdjBW:
- aminoglycosides
Which weight should be used when calculating creatinine clearance if the pt is underweight, normal weight, overweight w/ BMI < 25, and overweight w/ BMI ≥ 25?
Underweight - TBW
Normal weight - IBW
BMI < 25 - IBW
BMI ≥ 25 - AdjBW
What does it mean when pH > pKa? What does it mean when pH = pKa? What about wehn pH < pKa?
pH > pKa = more of the acid is ionized
pH = pKa = 50% of the solution is ionized
pH < pKa = for of the acid is un-ionized
What is the pH equation for a weak acid?
pH = pKa + log [salt/acid]
What are the two equations to find pH with a weak base?
pH = (14 - pKb) + log [base/salt]
pH = pKa + log [base/salt]
What are the equations to calculate the % ionization of a weak acid and weak base?
Weak acid:
% ionization = 100 / (1 + 10^(pKa -pH))
Weak base:
% ionization = 100 / (1 + 10^(pH - pKa))
What % elemental calcium does calcium carbonate and calcium citrate have? Do they need to be taken with food or without?
calcium carbonate - 40% elemental calcium
- acid-dependent absorption. take with food
calcium citrate - 21% elemental calcium
- acid-independent absorption. take with or without food
How do you convert from aminophylline to theophylline, then vice versa?
aminophylline to theophylline = multiply by 0.8
theophylline to aminophylline = divide by 0.8
What is the equation to calculate ANC?
ANC = WBC x [(%segs + %bands)/100]
