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Flashcards in Lange Ch22 Deck (12):
1

How much is physiologic dead space? Per weight?

1 cc per lb. so average physiologic dead space is 150cc

2

Bohr equation for dead space to tidal volume ratio Vd/Vt

Vd/Vt = (PACO2 - PeCO2) / PACO2. Avg ratio is 33% for 150/450. PeCO2 is mixed expired

3

Relationships of Pa, Pv, and PA in the 3 lung zones

Zone 1: PA > Pa > Pv, high V/Q
Zone 2: Pa > PA > Pv
Zone 3: Pa > Pv > PA, low V/Q
Ventilation and perfusion improve in dependent areas

4

How to calculate PAO2?

PAO2 = FiO2*(760-47) - (PCO2 / 0.8)

PAO2 ~ FiO2 * 6

5

MC mechanism of hypoxemia

Increased A-a gradient caused by R->L shunt, V/Q mismatch, low MvO2 (low cardiac output, high O2 consumption, anemia)

6

Venous admixture (physiologic shunt) equation

Qs/Qt = (CcO2 - CaO2) / (CcO2 - CvO2)
Normal shunt is 5%

7

Total oxygen delivery (DO2) equation

DO2 = cardiac output * arterial O2 content

8

Oxygen consumption VO2 equation

VO2 = cardiac output * (arterial O2 content - mixed venous O2 content)

9

Oxygen content equation

(O2sat * hgb * 1.31) + (PO2 * 0.003)

10

Mixed venous oxygen content equation

CvO2 = CaO2 - (VO2 / Qt)
VO2 oxygen consumption ~ 250 mL/min
Qt cardiac output

11

Basic breathing rhythm originates from what part of brain?

Medulla

12

Effect of anesthesia on peripheral ventilatory response to hypoxemia

Abolished response