Respiratory causes of hypoxemia are all except:

Ref: Pai GK. Hypoxia and Oxygen therapy. In: Textbook of Medical Physiology. 2nd ed. Ahuja Publishing House. 2011: 94: 758-59.Explanation:Hypoxic hypoxia - PO2 of the arterial blood is reducedEg:High altitude flow PO2 in inspired air)Hypoventilation (airway obstruction, respiratory muscle paralysis depression of respiratory centers, scoliosis)Diffusion defect - pulmonary edema, fibrosis, lung collapseVentilation/ Perfusion mismatch - A-V shunt, atelectasis lung collapse, cyanotic heart diseaseDead spaceIt is the space within the airways that do not allow gas exchange with pulmonary capillary bloodAnatomical dead space -Conducting respiratory pathway from nose to terminal bronchiolesAbout 150 ml (25-30% of minute ventilation)