Pulm Equations

Question 1

PAO2

Answer 1

PAO2 = PIO2 - (PaCO2 * 1.2)

Question 2

PIO2

Answer 2

PIO2 = (PB - 47)(0.21)

Question 3

Fa (fractional concentration of gas “a”)

Answer 3

Fa = Na / Ntotal

Question 4

Pa (partial pressure of gas “a”)

Answer 4

Pa = (Fa)(Ptotal)

Question 5

compliance

Answer 5

compliance = change in lung volume/change in Ptp

Question 6

MV (minute ventilation)

Answer 6

MV = (TV)(RR)

Question 7

R (airway resistance)

Answer 7

R = PB - Palv / airflow

Question 8

VD/VT (physiologic)

Answer 8

VD/VT = PaCO2 - PECO2 / PaCO2

Question 9

total blood O2

Answer 9

total blood O2 = (Hb * 1.34 * % sat) + (0.003 * PO2)

Question 10

VA (alveolar ventilation)

Answer 10

VA = VCO2 / PaCO2

Question 11

VO2 (Oxygen ventilation)

Answer 11

VO2 = Q([aO2] - [vO2])

Question 12

DLgas (diffusion capacity of the lung for a gas)

Answer 12

DLgas = Vgas / (PAgas - Pcapgas)

Question 13

HH equation general relationship

Answer 13

pH = HCO3- / PCO2

Question 14

[H+]

Answer 14

[H+] = 24 (PCO2 / [HCO3-])

Question 15

expected pCO2

Answer 15

expected pCO2 = (1.5[HCO3-]) + 8 +/-2

Question 16

A change in 10 mmHg PaCO2 will cause a change in how much pH for chronic and acute conditions?

Answer 16

acute: 0.08
chronic: 0.03

Question 17

bicarb and CO2 equation

Answer 17

CO2 + H2O H2CO3 H+ + HCO3-

Question 18

(AV) Alveolar ventilation

Answer 18

AV = (TV - DS)(RR)