Equations

Question 1

Sensitivity

Answer 1

Proportion of all people with disease who test positive

Does not vary with diesase prevelance

Question 2

Specificity

Answer 2

Proportion of all people without disease to test negative

Does not vary with disease prevelance

Question 3

Positive predictive value

Answer 3

Proportion of test results that are true positive

PPV and NPV vary with disease prevelance

Question 4

Negative predictive value

Answer 4

Proportion of negative test results that are true negative

PPV and NPV vary with disease prevelance

Question 5

Relative risk

Answer 5

Probabilty of getting a disease in the exposed group divided by the probability of getting a disease in the unexposed group

Measure of Cohort studies

Question 6

Attributable risk

Answer 6

Difference in risk between exposed and unexposed groups of getting the disease

Question 7

Number needed to treat

Answer 7

(Number needed to treat to prevent 1 more disease case)

Ideal NNT =1 (everyone treated gets cured)

Question 8

Number needed to harm

Answer 8

(Number of people who need to exposed to risk factor to cause 1 more disase case)

Very bad NNH = 0

Question 9

Hardy-Weinberg equalibrium

Answer 9

Question 10

Henderson-Hasselbach equation

Answer 10

Question 11

Volume of distribution

Answer 11

Question 12

Clearance

Answer 12

Question 13

Half-life

Answer 13

Question 14

Loading dose

Answer 14

Question 15

Maintenance dose

Answer 15

Question 16

Cardiac output

(2 equations)

Answer 16

CO= Stroke volume * Heart Rate

Question 17

Mean arterial pressure

Answer 17

Question 18

Stroke volume

Answer 18

Question 19

Ejection fraction

Answer 19

Normal Ejection fraction > 55%

Question 20

Arterial resistnace

Answer 20

Directly proportional to viscosity and length

Indrectly proportional to radius⁴

Question 21

Net filtration pressure

Answer 21

Question 22

Glomerular filtration rate

(2 equations)

Answer 22

GFR = K_f [(P_GC - P_BS) - π_GC - π_BS)]

Question 23

Effective renal plasma flow

Answer 23

Question 24

Renal blood flow

Answer 24

Question 25

Filtration fraction

Answer 25

Question 26

Physiologic dead space

Answer 26

Question 27

Odds ratio

Answer 27

Odds of having disease in exposed group divided by odds of having disease in unexposed group

Measure of Case-Control studies

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

Question 28

Winter’s formula

Respiratory compensation in metabolic acidosis

Answer 28

P_CO2 = 1.5 (HCO₃^-) + 8

(+/- 2)

Question 29

A-a gradient

Answer 29

P_AO₂ = 150 - (P_aCO₂/0.8)

A-a gradient = P_AO₂-P_aO₂

Normal (10-15mmHg)