Calculations Flashcards
What is the formula for calculating renal plasma flow (RPF)?
RPF = RBF x (1 - Hematocrit) or RPF = (urine [PAH] x V) / plasma [PAH]
How is minute ventilation and alveolar ventilation calculated?
- Minute (L/min) = tidal volume (L) x breaths/min
- Alveolar (L/min) = (tidal volume - dead space volume) x breaths/min
What is Winter’s formula?
Expected PaCO2 = [1.5 x (serum HCO3-) + (8 ± 2)]
Calculation for half-life (t1/2) of drug when given volume of distribution (Vd) and clearance rate (CL)?
t1/2 = (0.7 x Vd) / CL
How can you calculated the GFR and the RPF?
- GFR = [U] inulin or creatinine x V / [P] inulin or creatinine
- RPF = [U]PAH x V / [P]PAH
- FF = GFR/RPF
*V = urine flow rate (mL/min)
Formula for renal blood flow (RBF)?
RBF = RPF / (1 - Hct) or (PAH clearance) / (1 - Hct)
How to calculate SV and use this to calculate EF?
- SV = EDV - ESV
- EF = SV / EDV = (EDV - ESV) / (EDV)
What is the formula for loading dose and maintenance dose?
- LD = (CP x Vd) / F
- MD = (CP x CL x t) / F
*CP = Css or target steady state [plasma]
* CL = clearance; t = elapsed time btw doses; F = bioavailability