RR - equation review

Question 1

Sensitivity

Answer 1

SN = TP / (TP + FN)

True positives / total with disease

Question 2

Specificity

Answer 2

SP = TN / (TN + FP)

True negatives / total without disease

Question 3

Positive predictive value

Answer 3

PPV = TP / (TP + FP)

True positives / total positives

Question 4

Negative predictive value

Answer 4

NPV = TN / (TN + FN)

True negatives / total negatives

Question 5

Odds ratio

Answer 5

OR = (a/c) / (b/d) = ad/bc

Question 6

Relative risk

Answer 6

RR = a/(a+b) / c/(c+d)

Question 7

Attributable risk

Answer 7

Attributable risk = a/(a+b) - c/(c+d)

Question 8

NNT

Answer 8

NNT = 1/ARR

Question 9

Number needed to harm

Answer 9

1/attributable risk

Question 10

BMI

Answer 10

BMI = weight in kg/(height in m)^2

Question 11

Hardy Weinberg equilibrium

Answer 11

p^2 + 2pq + q^2 = 1

p + q = 1

Question 12

Volume of distribution

Answer 12

Vd = amount of drug in body / plasma drug concentration

Question 13

Half life

Answer 13

t1/2 = (0.7 x Vd) / CL

Question 14

Drug clearance

Answer 14

CL = rate of elimination of drug / plasma drug concentration
CL = Vd x Ke (elimination constant)

Question 15

Loading dose

Answer 15

LD = Cp x (Vd/F)

F is bioavailability

Question 16

Maintenance dose

Answer 16

MD = Cp x (CL/F)

F is bioavailability

Question 17

Cardiac output

Answer 17

CO = SV x HR
CO = rate of O2 consumption / (arterial O2 content - venous O2 content)

Question 18

Mean arterial pressure

Answer 18

MAP = C.O. x TPR
MAP = 2/3diastolic + 1/3systolic

Question 19

Stroke volume

Answer 19

SV = C.O. / HR = EDV - ESV

Question 20

Ejection fraction

Answer 20

EF = SV/EDV = (EDV - ESV)/EDV

Question 21

Resistance

Answer 21

R = driving pressure (P)/flow (Q)
R = 8n (viscosity) x length / (pi)r^4

Question 22

Net filtration pressure

Answer 22

Pnet = [(Pc - Pi) - (oncotic cap - oncotic int)]
Jv = net fluid flow = (Kf)(Pnet)

Question 23

Renal clearance

Answer 23

C(of x) = UxV/Px

V = urine volume

Question 24

Glomerular filtration rate

Answer 24

GFR = UV/P
for inulin
GFR = Kf [(Pgc - Pbs) - (Oncgc - Oncbs)]

Question 25

Effective renal plasma flow

Answer 25

ERPF = UV/P

for PAH

Question 26

Renal blood flow

Answer 26

RBF = RPF/(1-HCT)

Question 27

Filtration fraction

Answer 27

FF = GFR/RPF

Question 28

Henderson Hasselbalch (for extracellular pH)

Answer 28

pH = 6.1 + log ([HCO3-]/.03xPCO2)

Question 29

Physiologic dead space

Answer 29

Vd = Vt x [(PaCO2 - PeCO2)/PaCO2]

Question 30

Pulmonary vascular resistance

Answer 30

PVR = (Pulm art pressure - L atrium pressure) / C.O.

Question 31

Alveolar gas equation

Answer 31

PAO2 = PIO2 - (PaCO2/R)

Question 32

A-a gradient

Answer 32

PAO2 = (FIO2 x PO2) - PaCO2/R
PAO2 = .21(760-43) - 40/.8 = 100 (normally)