<prompt> Respiratory causes of hypoxemia are all except:HypoventilationPhysiological ShuntVP mismatchDead space ventilation  <response>: 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 airHypoventilation airway obstruction, respiratory muscle paralysis depression of respiratory centers, scoliosisDiffusion 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 