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This contrasts with the classical explanation of HPV which presumes that hypoxia is sensed at the pulmonary artery smooth muscle cell itself. Specialized epithelial cells (neuroepithelial bodies) that release serotonin have been suggested to contribute to hypoxic pulmonary venoconstriction. [8]
Hypoxic pulmonary vasoconstriction (HPV) occurs diffusely, leading to arterial vasoconstriction in all areas of the lung. This is evidenced by the appearance of "diffuse," "fluffy," and "patchy" infiltrates described on imaging studies of climbers with known HAPE.
Chronic hypoxic pulmonary vasoconstriction (can cause right ventricular hypertrophy) People with high-altitude sickness generally have reduced hyperventilator response, impaired gas exchange, fluid retention or increased sympathetic drive.
By contrast, in the lungs, the response to hypoxia is vasoconstriction. This is known as hypoxic pulmonary vasoconstriction, or "HPV", and has the effect of redirecting blood away from poorly ventilated regions, which helps match perfusion to ventilation, giving a more even oxygenation of blood from different parts of the lungs. [81]
Two causes are vascular changes as a result of tissue damage (e.g. disease, hypoxic injury), and chronic hypoxic pulmonary vasoconstriction. If left untreated, then death may result. The heart and lungs are intricately related; whenever the heart is affected by a disease, the lungs risk following and vice versa. [citation needed]
[50] [51] It has been established that combined burn and smoke inhalation injury impairs hypoxic pulmonary vasoconstriction (HPV), the vasoconstrictive response to hypoxia, thereby mismatching ventilation with perfusion. Gas exchange is affected by increases in the dispersion of both alveolar ventilation and cardiac output because bronchial and ...
The disease puts strain on the heart, which may lead to heart failure and leg swelling. Obesity hypoventilation syndrome is defined as the combination of obesity and an increased blood carbon dioxide level during the day that is not attributable to another cause of excessively slow or shallow breathing. [2]
The last line of this article explains why HPV might occur; however, this explanation is not entirely correct. The lung reacts to hypoxia with constriction of vasculature exposed to hypoxia in order to shunt blood to regions of the lung that are better ventilated, not to affect increased blood flow to "unused parts of the lungs".