Equations

Question 1

Half-life

Answer 1

T1/2= (0.7*Vd)/(CL)

Question 2

Maintenance dose

Answer 2

MD=(Steady state plasma concentration*CL)/(Bioavailibility fraction)

Question 3

Loading dose

Answer 3

LD=(Volume of distribution * Steady state plasma concentration)/(Bioavailability fraction)

Question 4

Cardiac output (using oxygen stuff)

Answer 4

CO=O2 consumption/arteriovenous difference

Question 5

Volume of distribution (Vd)

Answer 5

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

Question 6

Minute ventilation

Answer 6

Tidal volume x breath rate

Question 7

Alveolar ventilation

Answer 7

(Tidal volume-dead space) x breath rate

Question 8

Odds ratio

Answer 8

OR=(A/C)/(B/D)

or

OR=(AD)/(BC)

used in case-control studies

Question 9

Odds ratio in words

Answer 9

Odds that the group w/ the disease (A/C) was exposed to the risk factor divided by the odds those w/out the disease (B/D) were exposed

Question 10

Attributable risk

Answer 10

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

Question 11

Number needed to treat

Answer 11

1/absolute risk reduction

Question 12

Absolute risk reduction example

Answer 12

8% of people who receive a placebo develop disease and 2% of people who get vaccine develop the disease, the ARR is 6% (8-2=6, high level stuff)

Question 13

Number needed to harm

Answer 13

1/attributable risk

Question 14

Body mass index (BMI)

Answer 14

BMI=Weight(kg)/height(m)^2

Question 15

Hardy-Weinberg equation

Answer 15

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

Question 16

Drug clearance

Answer 16

CL=rate of elimination/plasma drug concentration

or Vd*Ke(elimination constant)

Question 17

Mean arterial pressure

Answer 17

CO*TPR=2/3 diastolic + 1/3 systolic

Question 18

Stroke volume

Answer 18

CO/HR=EDV-ESV

Question 19

Ejection fraction

Answer 19

SV/EDV=(EDV-ESV)/EDV

Question 20

Resistance

Answer 20

P/Q=(8n(viscosity))length/(pier^4)

Question 21

Renal clearance

Answer 21

Cx=(Ux*V)/Px

Question 22

GFR

Answer 22

GFR=Cinulin=Uinulin*V/Pinulin (creatinine can also be used to estimate)

Question 23

Renal plasma flow

Answer 23

RPF=Cpah=Upah*v/Ppah

Question 24

Renal blood flow

Answer 24

RBF=RPF/(1-Hct)

Question 25

Filtration fraction

Answer 25

FF=(GFR/RPF)

Question 26

Physiologic dead space

Answer 26

Vd-Vt*((PaCO2-PECO2)/PaCO2

Question 27

Pulmonary vascular resistance (PVR)

Answer 27

PVR=(Pulmonary artery pressure-LA pressure)/CO

Question 28

Alveolar gas equation

Answer 28

PAO2=PIO2- PaCO2/.8 (respiratory quotient)

Question 29

Alveolar-arterial gradient (A-a gradient)

Answer 29

A-a=PAO2-PaO2

Question 30

What’s a normal A-a gradient

Answer 30

~10-14

Question 31

Inspiratory capacity (IC)

Answer 31

IC=TV+IRV

Question 32

Functional residual capacity (FRC)

Answer 32

FRC=ERV+RV

Question 33

Vital capacity (VC)

Answer 33

VC=TV+IRV+ERV=IC+ERV

Question 34

Total lung capacity (TLC)

Answer 34

TLC=TV+IRV+ERV+RV=VC+RV=IC+ERV+RV

Question 35

Excretion rate

Answer 35

Excretionx=V*Ux

Question 36

Filtered load

Answer 36

Filtered loadx=GFR*Px

Question 37

Reabsorption

Answer 37

Reabsorption=Filtered-excreted

Question 38

Secretion

Answer 38

Secretion=Excreted-filtered

Question 39

If Cx<GFR…

Answer 39

Net reabsorption

Question 40

If Cx>GFR…

Answer 40

Net secretion

Question 41

If Cx=GFR…

Answer 41

Neither secreted or reabsorded

Question 42

Winter’s formula

Answer 42

PCo2=1.5(bicarb)+8 +/-2

Question 43

Anion gap

Answer 43

Anion gap=Na -(Cl+bicarb)

Question 44

Resistance in Series

Answer 44

Rtotal=R1+R1+R3…

Question 45

Resistance in parallel

Answer 45

1/Rtotal=1/R1+1/R2+1/R3…