Functional Factors
Hypoxia (==most important factor, controllable==)
Hypercapnia (second most important factor)
Respiratory acidosis causing pulmonary vascular contraction and spasm
Anatomical Factors
- Chronic recurrent COPD leads to adjacent pulmonary arteritis, thickening of vessel walls
, narrowing of the lumen
, and increased pulmonary vascular resistance - Pulmonary emphysema causes increased alveolar pressure, compressing and narrowing alveolar capillaries
- Chronic hypoxia leads to pulmonary vascular remodeling
- Thrombosis increases pulmonary vascular resistance
Increased Blood Viscosity and Blood Volume
- Hypoxia secondary polycythemia increases blood viscosity
- Hypoxia increases aldosterone, causing water and sodium retention
- Hypoxia causes contraction of renal arterioles, reducing renal blood flow and increasing water and sodium retention