Hypoxia/Hypoxemia Lecture 13

Question 1

Types of Hypoxia (4)

Answer 1

Ischemia, Hypoxia, Histotoxic, Anemia

Question 2

Causes of Hypoxemia (5)

Answer 2

Hypoventilation, Lower PIO2, Low V/Q, R-L shunt, diffusion impairment

Question 3

Alveolar dead space compensations

Answer 3

Bronchoconstriction secondary to respiratory alkalosis;

Decreased alveolar compliance secondary to surfactant loss

Question 4

Venous admixture

Answer 4

mixing of non-ventilated blood with ventilated blood, causing a large increase in AaO2

Question 5

what makes up the usual (normal) R-L shunt?

Answer 5

thebesian circulation (around the heart) and bronchial circulation

Question 6

In the Tetrology of Fallot how much blood can be shunted past the pulmonary circulation?

Answer 6

75%

Question 7

Pathological shunting causes

Answer 7

Pneumonia, ARDS, pulmonary edema (CHF)

Question 8

Pathological shunting is a sign of…

Answer 8

abnormalities in the vasoregulatory system (those alveoli that do not function should be shutoff by HPV

Question 9

L-to-R shunts lead to R-to-L shunts because…

Answer 9

the pressure of the left ventricle inside the pulmonary circulation produces muscular hypertrophy of the circular muscle leading to pulmonary hypertension which causes extreme afterload which results in R-to-L shunting

Question 10

Causes of hypoventilation

Answer 10

BNA - brain, nerve, airway

Question 11

diffusion impairment is secondary to which disease processes?

Answer 11

emphysema, ARDS and advanced lung fibrosis

Question 12

aging causes what changes to ventilation?

Answer 12

decreased compliance, decreased strength of accessory muscles, decreased elastic recoil, decreased functioning alveoli, increased physiological dead space

Question 13

what’s the formula for alveolar ventilation as it relates to tidal volume and dead space?

Answer 13

Va = Vt - Vd

Question 14

Hypercapnia can be caused by

Answer 14

hypoventilation (#1) or severe V/Q mismatch brought on by CHF

Question 15

Rates for FEV1/FVC

Answer 15

20% in severe asthma attack, 47% in obstructed airway and 80% normally

Question 16

obstructive diseases cause a drop in FEV1/FVC because

Answer 16

dynamic airway obstruction reduces the ability to exhale rapidly; loss of elastic recoil and airway narrowing

Question 17

restrictive disease has what effect on FEV1/FVC

Answer 17

there is no drop as the ratio does not change, just the total amount

Question 18

chronic bronchitis of COPD

Answer 18

excess mucous, paralysis of cilia, inhibition of alveolar macrophages, inflammatory edema of epithelium in airways

Question 19

genetic predisposition to COPD is caused by

Answer 19

alpha-1-antitrypsin