Equation Review Flashcards
Sensitivity
TP/(TP+FN)
A/(A+C)
1- false negative rate
Specificity
TN/(TN+FP)
D/(B+D)
1- false positive rate
Positive predictive value
TP/(TP+FP)
A/(A+B)
Negative predictive value
TN/(FN+TN)
D/(C+D)
Odds ratio (for case control studies)
(a/c)/(b/d) = ad/bc
Relative risk
(a/[a+b])/(c/[c+d])
Attributable risk
(a/(a+b)) - (c/(c+d))
Number needed to treat
1/absolute risk reduction
Number needed harm
1/attributable risk
Hardy-Weinberg equilibrium
p^2+2pq+q^2 = 1 and p+q=1
Volume of distribution
Vd = amount of drug in the body/plasma drug concentration
Half-life
(0.693 x Vd)/CL
Drug clearance
CL = rate of elimination of drug/plasma drug concentration = Vd x Ke (elimination constant)
Loading dose
LD = (Cp x Vd)/F
Maintenance dose
D = (Cp x CL x t)/F … t = dosing interval
Cardiac output
CO = rate of O2 consumption/(arterial O2 content-venous O2 content) … CO = SVxHR
Mean arterial pressure
MAP = COxTPR … MAP = 2/3(diastolic)+1/3(systolic)
Stroke volume
EDV-ESV
Ejection fraction
EF = SV/EDV = (EDV-ESV)/EDV
Resistance
driving pressure (ΔP)/flow (Q) = (8η x length)/πr^4
Net filtration pressure
Pnet = [(Pc-Pi) - (πc-πi)] …. Jv = net fluid flow = (Kf)(Pnet)
Renal clearance
Cx = UxV/Px
Glomerular filtration rate
GFR = Uinulin x V/Pinulin = Cinulin … GFR = Kf[(Pg - Pb)-(πg - πb)]
Normal: 100 ml/min
Effective renal plasma flow
ERPF = Upah x (V/Ppah) = Cpah
Underestimates true renal plasma flow by 10%
