Rapid Review - Equation Review (1)

Question 1

Sensitivity

Answer 1

Sensitivity = TP / (TP + FN)

Question 2

Specificity

Answer 2

Specificity = TN / (TN + FP)

Question 3

Positive predictive value

Answer 3

PPV = TP / (TP + FP)

Question 4

Negative predictive value

Answer 4

NPV = TN / (FN + TN)

Question 5

Odds ratio (for case-control studies)

Answer 5

Odds ratio = (a/c) / (b/d) = (ad) / (bc)

Question 6

Relative risk

Answer 6

Relative risk = [ a / (a+b) ] / [c / (c+d) ]

Question 7

Attributable risk

Answer 7

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

Question 8

Number needed to treat

Answer 8

1 / absolute risk reduction

Question 9

Number needed to harm

Answer 9

1 / attributable risk

Question 10

Hardy-Weinberg equilibrium

Answer 10

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

p + q = 1

Question 11

Volume of distribution

Answer 11

Vd = (amount of drug in the body) / (plasma drug concentration)

Question 12

Half-life

Answer 12

t1/2 = (0.693 × Vx) / CL

Question 13

Drug clearance

Answer 13

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

Question 14

Loading dose

Answer 14

LD = (Cp × Vd) / F

Question 15

Maintenance dose

Answer 15

MD = (Cp × CL × tau) / F

Question 16

Cardiac output

Answer 16

CO = (rate of O2 consumption) / [ (arterial O2 content) - (venous O2 content) ]
CO = stroke volume × heart rate

Question 17

Mean arterial pressure

Answer 17

MAP = cardiac output × total peripheral resistance
MAP = 2/3 (diastolic) + (1/3) systolic

Question 18

Stroke volume

Answer 18

SV = EDV – ESV

Question 19

Ejection fraction

Answer 19

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

Question 20

Resistance

Answer 20

Resistance = [driving pressure (deltaP)] / [flow (Q)]
Resistance = (8 × eta × viscosity × length) / (π × r^4)

Question 21

Net filtration pressure

Answer 21

Pnet = [(Pc - Pi) - (πc - πi)]
Jv = net fluid flow = (Kf) × (Pnet)

Question 22

Renal clearance

Answer 22

Cx = (Ux × V) /Px

Question 23

Glomerular filtration rate

Answer 23

GFR = (Uinulin × V) / Pinulin = Cinulin
GFR = Kf [(PGC – PBS) – (πGC – πBS)]

Question 24

Effective renal plasma flow

Answer 24

ERPF = UPAH × (V / PPAH) 
ERPF = CPAH

Question 25

Renal blood flow

Answer 25

RBF = RPF / (1 − Hct)

Question 26

Filtration fraction

Answer 26

FF = GFR / RPF

Question 27

Henderson-Hasselbalch equation (for extracellular pH)

Answer 27

pH = 6.1 + log{ [HCO3-] / (0.03 × PCO2) }

Question 28

Winters formula

Answer 28

Pco2 = 1.5 [HCO3–] + 8 +/- 2

Question 29

Physiologic dead space

Answer 29

VD = VT × [ (PaCO2 − PECO2) / PaCO2 ]

Question 30

Pulmonary vascular resistance

Answer 30

PVR = (Ppulmartery - PLatrium) / cardiac output

Question 31

Alveolar gas equation

Answer 31

PAo2 = PIo2 – (Paco2 / R)