First Aid 2014 Rapid Review Equation Review

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) = (a × d) / (b × c)

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

NNT = 1/(absolute risk reduction)

Question 9

Number needed to harm

Answer 9

NNH = 1/(attributable risk)

Question 10

Hardy-Weinberg equilibrium

Answer 10

p² + 2pq + q² = 1 AND 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

t½ = (0.693 × Vd) / (CL)

Question 13

Drug clearance

Answer 13

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

Question 14

Loading dose

Answer 14

LD = (Cp × Vd) / (F)

Question 15

Maintenance dose

Answer 15

D = (Cp × CL × tau) / (F)

Question 16

Cardiac output

Answer 16

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

Question 17

Mean arterial pressure

Answer 17

MAP = (cardiac output) × (total peripheral resistance) OR 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) = (EDV−ESV) / (EDV)

Question 20

Resistance

Answer 20

Resistance = (driving pressure) / (flow) = (∆P) / (Q) = (8η [viscosity] × length ) / (πr⁴)

Question 21

Net filtration pressure

Answer 21

Pnet = [(Pc - Pi) - (πc - πi)] OR 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 OR GFR = Kf [(Pgc - Pbs) - (πgc - πbs)]

Question 24

Effective renal plasma flow

Answer 24

ERPF = Upah × (V / Ppah) = 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 = (P pulm artery - P l atrium) / (cardiac output)

Question 31

Alveolar gas equation

Answer 31

PAo₂ = PIo₂ - ( Paco₂ / R )