Equations

Question 1

Alveolar Gas Equation

Answer 1

PAO2 = ((Pb-H2O)xFiO2)-(PaCO2/0.8)

Question 2

Shunt Equation

Answer 2

QS/QT = (CcO2-CaO2)/(CcO2-CvO2)

Question 3

Pulmonary Vascular Resistance

Answer 3

PVR = ((MPAP - PCWP) x 80) / CO

Question 4

Plasma Osmolarity

Answer 4

2(Na + K) + Glucose + Urea

Question 5

Anion Gap

Answer 5

(Na + K) - (Cl + HCO3)

Question 6

Bohr Equation

Answer 6

VD/VT = (PaCO2 - PECO2)/PaCO2

Question 7

Oxygen Delivery

Answer 7

DO2 = CO x (1.34 x Hb x SpO2) + (0.003 x PaO2)

Question 8

Respiratory Compliance

Answer 8

1/(C Total) = 1/(C Chest) + 1/(C Lung)

Question 9

Clearance

Answer 9

Cl x Cp = Cu x Vu
Cl - Clearance
Cp - Plasma Concentration
Cu - Urine Concentration
V - Urine flow (ml/min)

Question 10

pH

Answer 10

pH = -log(H+)

Question 11

Fick’s Law

Answer 11

Q = (ΔP x A x D) / T
Q - flow
ΔP - Pressure difference
A - Surface area
D - Diffusion constant (gas specific)
T - membrane thickness

Question 12

Boyle’s Law

Answer 12

P1V1 = P2V2
Assuming temperature is constant

Question 13

Charle’s Law

Answer 13

V1/T1 = V2/T2
Assuming pressure is constant

Question 14

Gay-Lussac’s Law

Answer 14

P1/T1 = P2/T2
Assuming V is constant

Question 15

Henry’s Law

Answer 15

C = kP
The amount of dissolved gas in a liquid is proportionate to the partial pressure of the gas above the liquid

Question 16

Dalton’s Law

Answer 16

Total pressure = sum (all individual gas partial pressures dissolved in a liquid)

Question 17

Hagen - Poiseuille

Answer 17

Q = (ΔP x π x r^4) / (8 x η x l)

Question 18

Reynold’s Number

Answer 18

Re = ρvd / η
ρ - density
v - velocity
d - diameter of tube
η -viscosity

Question 19

Universal Gas Law

Answer 19

pV = nRT

Question 20

Cerebral Perfusion Pressure

Answer 20

CPP = MAP - (ICP + CVP)