Calculations

Question 1

A-a Gradient

Answer 1

PAO2 - PaO2

Question 2

Alveolar Gas Equation

Answer 2

PAO2 = FiO2 • (PATM - Pwater vapor) - PaCO2 / RQ

Question 3

Dynamic Compliance (Cdyn) =

Answer 3

Tidal Volume /Peak Pressure - PEEP

Question 4

Minute Ventilation =

Answer 4

RR * Tidal Volume

Question 5

Predicted PaO2 by Age =

Answer 5

110- (Age *0.4)

Question 6

Reynold’s Number =

Answer 6

(Velocity * Density * Diameter) / Viscosity

Question 7

Static Compliance (Cstat) =

Answer 7

TV / (Plateau Pressure - PEEP)

Question 8

Transpulmonary Pressure =

Answer 8

Alveolar Pressure - Pleural Pressure

Question 9

Transthoracic Pressure =

Answer 9

Pleural Pressure - Atmospheric Pressure

Question 10

Dead Space to Tidal Volume Ratio =

Answer 10

Vd/Vt Ratio = Vd / Vt

Question 11

Cardiac Output =

Answer 11

HR x SV

Question 12

Coronary Perfusion Pressure =

Answer 12

DBP - LVEDP (or PAOP)

Question 13

Ejection Fraction =

Answer 13

EDV - ESV / EDV

Question 14

Fick Principle

Cardiac Output =

Answer 14

(VO2 / CaO2 - CvO2) x 100

Question 15

Law of LaPlace (Cylinder)

Wall Tension (cylinder) =

Answer 15

(Pressure x Radius) / Wall Thickness

Question 16

Law of LaPlace (Sphere)

Wall Tension (Sphere) =

Answer 16

(Pressure x Radius) / 2 x Wall Thickness

Question 17

Maximum Allowable Blood Loss =

Answer 17

EBV x (Starting Hgb - Target Hgb)/ Starting Hgb

Question 18

MAP =

Answer 18

[SBP + (DBP * 2)] / 3

Question 19

Oxygen Carrying Capacity / Oxygen Content

CaO2 =

Answer 19

(Hgb x SaO2 x 1.34) + (PaO2 x 0.003)

Question 20

Oxygen Delivery

DO2 =

Answer 20

(Hgb x SaO2 x 1.34) + (PaO2 x 0.003) x CO x 10

Question 21

Oxygen Extraction Ratio

ER =

Answer 21

Oxygen Consumption / Oxygen Delivery

Question 22

Poiseuille’s Law

Flow =

Answer 22

(π • Radius4 • ∆Pressure) /

8 • Viscosity • Length

Question 23

Pulmonary Vascular Resistance =

Answer 23

[ (Mean PA Pressure - PAOP) / CO ] x 80

Question 24

Pulse Pressure =

Answer 24

SBP - DBP

Question 25

Systemic Vascular Resistance =

Answer 25

[ (MAP - CVP) / CO ] x 80

Question 26

Stroke Volume (Version 1) =

Answer 26

CO x 1000 / HR

Question 27

Stroke Volume (Version 2) =

Answer 27

End Diastolic Vol - End Systolic Volume

Question 28

Uncuffed ETT size =

Answer 28

Age / 4 + 4

Question 29

Cuffed ETT size =

Answer 29

Age / 4 + 3.5

Question 30

O2 Remaining in Oxygen E-Cylinder: Step 1 Step 2

Answer 30

``` Step 1: Tank Capacity (L)/ Full Tank Pressure (psi) = Contents Remaining (L) = Gauge Pressure (psi) ``` ``` Step 2: Contents Remaining (L) / Flow Rate (L/min) = Minutes Left ```

Question 31

Fraction of Inspired Oxygen (FIO2) =

Answer 31

[ (Oxygen Flow Rate x 100) + (Air Flow Rate x 21) ] / Total Flow Rate

Question 32

Gas Tanks (E) Air - Volume, Pressure, Pin

Answer 32

Air: - Vol: 660L - Pressure: 1900psig - Pin: 1-5

Question 33

Gas Tanks (E) Oxygen- Volume, Pressure, Pin

Answer 33

Oxygen: - Vol: 660L - Pressure: 1900psig - Pin: 2-5

Question 34

Gas Tanks (E) N2O- Volume, Pressure, Pin

Answer 34

N20: - Vol: 1590L - Pressure: 745psig - Pin: 3-5

Question 35

Cerebral Perfusion Pressure =

Answer 35

MAP - ICP (or CVP whichever is higher)

Question 36

Anion Gap =

Answer 36

[Na+] - ( [Cl-] + [HCO3-])

Question 37

Plasma Osmolarity =

Answer 37

2 [Na+] + Glucose/18 + BUN/2.8

Question 38

Boyle's Law:

Answer 38

P1 x V1 = P2 x V2

Question 39

Gay Lussac's Law:

Answer 39

P1/T1 = P2/T2

Question 40

Charles' Law:

Answer 40

V1/T1 = V2/T2

Question 41

Ideal Gas Law:

Answer 41

Pressure x Volume = # moles x 0.0821 x temperature

Question 42

Celsius =

Answer 42

(F-32) x 5/9

Question 43

Dalton's Law:

Answer 43

P total = P1+ P2 + P3 ...

Question 44

Farenheit =

Answer 44

(C x 1.8) + 32

Question 45

Henderson Hasselbalch pH =

Answer 45

pK + log [HCO3 / (0.03 x PaCO2)]

Question 46

Henry's Law =

Answer 46

Partial Pressure = Constant x Concentration

Question 47

Inverse Square Law | Intensity =

Answer 47

1 / Distance ^2

Question 48

Volume of Distribution =

Answer 48

Dose / Concentration

Question 49

Half Life =

Answer 49

Volume of Distribution / Rate of Clearance