RR - equation review Flashcards
Sensitivity
SN = TP / (TP + FN)
True positives / total with disease
Specificity
SP = TN / (TN + FP)
True negatives / total without disease
Positive predictive value
PPV = TP / (TP + FP)
True positives / total positives
Negative predictive value
NPV = TN / (TN + FN)
True negatives / total negatives
Odds ratio
OR = (a/c) / (b/d) = ad/bc
Relative risk
RR = a/(a+b) / c/(c+d)
Attributable risk
Attributable risk = a/(a+b) - c/(c+d)
NNT
NNT = 1/ARR
Number needed to harm
1/attributable risk
BMI
BMI = weight in kg/(height in m)^2
Hardy Weinberg equilibrium
p^2 + 2pq + q^2 = 1
p + q = 1
Volume of distribution
Vd = amount of drug in body / plasma drug concentration
Half life
t1/2 = (0.7 x Vd) / CL
Drug clearance
CL = rate of elimination of drug / plasma drug concentration CL = Vd x Ke (elimination constant)
Loading dose
LD = Cp x (Vd/F)
F is bioavailability
Maintenance dose
MD = Cp x (CL/F)
F is bioavailability
Cardiac output
CO = SV x HR CO = rate of O2 consumption / (arterial O2 content - venous O2 content)
Mean arterial pressure
MAP = C.O. x TPR MAP = 2/3diastolic + 1/3systolic
Stroke volume
SV = C.O. / HR = EDV - ESV
Ejection fraction
EF = SV/EDV = (EDV - ESV)/EDV
Resistance
R = driving pressure (P)/flow (Q) R = 8n (viscosity) x length / (pi)r^4
Net filtration pressure
Pnet = [(Pc - Pi) - (oncotic cap - oncotic int)] Jv = net fluid flow = (Kf)(Pnet)
Renal clearance
C(of x) = UxV/Px
V = urine volume
Glomerular filtration rate
GFR = UV/P
for inulin
GFR = Kf [(Pgc - Pbs) - (Oncgc - Oncbs)]
Effective renal plasma flow
ERPF = UV/P
for PAH
Renal blood flow
RBF = RPF/(1-HCT)
Filtration fraction
FF = GFR/RPF
Henderson Hasselbalch (for extracellular pH)
pH = 6.1 + log ([HCO3-]/.03xPCO2)
Physiologic dead space
Vd = Vt x [(PaCO2 - PeCO2)/PaCO2]
Pulmonary vascular resistance
PVR = (Pulm art pressure - L atrium pressure) / C.O.
Alveolar gas equation
PAO2 = PIO2 - (PaCO2/R)
A-a gradient
PAO2 = (FIO2 x PO2) - PaCO2/R PAO2 = .21(760-43) - 40/.8 = 100 (normally)
