- drop in ventilation
-depression of resp. centre in brain
-airway obstruction
-disease of nerves supplying resp. muscles
-thoracic wall injury
4. Intrapulmonary shunting: Low V/Q
Nota:
-most common
-blood passes thru pulmonary system without being involved in gas exchange--> unoxygenated blood reenters arterial system & dilutes oxygenated blood
-atelectasis, consolidated pneumonia
2. Impaired diffusion
Nota:
-pathological changes--> poor O2 transfer into arterial blood
-Fick's Law: surface area
-membrane thickness
-Gas solubility- CO2 vs. O2
-pressure gradient