Equation Review

Question 1

volume of distribution

Answer 1

Vd = amount of drug in body/plasma drug concentration

Question 2

half-life

Answer 2

t1/2 = 0.7*Vd/CL

Question 3

drug clearance

Answer 3

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

Question 4

loading dose

Answer 4

LD = Cp*Vd/F

Question 5

maintenance dose

Answer 5

D = CpCLt/F

Question 6

sensitivity

Answer 6

sensitivity = TP/(TP+FN)

Question 7

specificity

Answer 7

specificity = TN/(TN+FP)

Question 8

positive predictive value

Answer 8

PPV = TP/(TP+FP)

Question 9

negative predictive value

Answer 9

NPV = TN/(FN+TN)

Question 10

odds ratio

Answer 10

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

Question 11

relative risk

Answer 11

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

Question 12

attributable risk

Answer 12

AR = a/(a+b) - c/(c+d)

Question 13

relative risk reduction

Answer 13

RRR = 1-RR

Question 14

absolute risk reduction

Answer 14

ARR = c/(c+d) - a/(a+b)

Question 15

number needed to treat

Answer 15

NNT = 1/ARR

Question 16

number needed to harm

Answer 16

NNH = 1/AR

Question 17

cardiac output

Answer 17

CO = rate of O2 consumption/(arterial O2 - venous O2)

CO = SV * HR

Question 18

mean arterial pressure

Answer 18

MAP = CO * TPR

MAP = 2/3 diastolic + 1/3 systolic

Question 19

ejection fraction

Answer 19

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

Question 20

resistance

Answer 20

resistance = driving pressure/flow = viscositylength/pir^4

Question 21

stroke volume

Answer 21

SV = EDV - ESV

Question 22

capillary fluid exchange

Answer 22

Jv = net fluid flow = Kf[(Pc-Pi)-(pic-pii)]

Question 23

renal clearance

Answer 23

Cx = Ux*V/Px

Question 24

glomerular filtration rate

Answer 24

GFR = Uinulin*V/Pinulin = Cinulin

GFR = Kf[(Pgc-Pbs) - (pigc-pibs)]

Question 25

effective renal plasma flow

Answer 25

eRPF = Upah*V/Ppah = Cpah

Question 26

renal blood flow

Answer 26

RBF = RPF/(1-Hct)

Question 27

filtration fraction

Answer 27

FF = GFR/RPF

Question 28

Henderson-Hesselbach equation (for extracellular pH)

Answer 28

pH = 6.1 + log([HCO3-]/0.03*Pco2)

Question 29

Winters formula

Answer 29

Pco2 = 1.5[HCO3-] +8 +/- 2

Question 30

physiologic dead space

Answer 30

V.D = V.T * (PaCO2 - PeCO2)/PaCO2

Question 31

pulmonary vascular resistance

Answer 31

PVR = (Ppulmartery - Platrium)/CO

Question 32

alveolar gas equation

Answer 32

PAO2 = PIO2 - PaCO2/R