Disorders of Ventilation and Gas Exchange Flashcards
There is ventilation but no matching blood supply (perfusion) is referred as
dead space
There is ventilation but no matching blood supply (perfusion) is referred as
dead space
Example of dead space
PE
When some alveoli have no ventilation due to an obstructed airway
shunt
Example of shunt
pulmonary edema
When some alveoli have no perfusion, due to occlusion of blood supply to that unit
dead space
PaO2 level in hypoxemia
Most common cause of hypoxemia
mismatched V/Q
Other causes of hypoxemia
decreased oxygen in inspired air (high altitude)
alveolar hypoventilation
diffusion abnormalities (pulmonary fibrosis and edema)
atelectasis
right-left shunt
congenital heart defect
Normal PaCO2 level
38-42 mmHg
Increased level of PaCO2
hypercapnia
What is the best measure of alveolar ventilation
PaCO2 level
Most common cause of hypercapnia
hypoventilation
Most common cause of hypocapnia
hyperventilation
Normal range for V/Q
0.6-3.0
average around 1
Refers to the blood supply to the alveoli
Perfusion
Refers to the air in the lungs available for gas exchange
Ventilation
Diseases related to impaired ventilation
airway obstruction
bronchoconstriction
pulmonary edema
Disease that increases the shunt fraction and leads to hypoxemia
pulmonary edema
Diseases related to impaired perfusion
emphysema
PE
In V/Q mismatch, which is more easily compensated, O2 or CO2
CO2
What is treatment to improve hypoxia r/t V/Q mismatching
FiO2 (inspired oxygen)
V/Q mismatch is charaterized as
hypoxia without or far in excess of hypercapnia
Subjective sensation of being unable to get enough air
dyspnea
