PVR in medicine means pulmonary vascular resistance, common causes of increased pulmonary vascular resistance are as follows: 1, chronic bronchitis, which can lead to the wall of the bronchial tubes thickening, narrowing, and in severe cases, can lead to bronchial and nasal congestion, which can compress the pulmonary vasculature, and is an increase in pulmonary vascular resistance, which will ultimately lead to pulmonary arterial hypertension.2, patients with chronic obstructive pulmonary disease, the main manifestation of emphysema, which will make the The pressure in the alveoli is higher than normal, compressing the capillaries of the alveoli, which also causes an increase in pulmonary vascular resistance.3. Respiratory diseases, usually a chronic hypoxic process, hypoxia will lead to vasoconstriction, increased tension in the wall of the tubes, and at the same time, it can lead to the thickening of the interstitial cells and the hardening of the walls of the blood vessels, which will lead to an increase in pulmonary vascular resistance. Increased pulmonary vascular resistance in the clinic is not conducive to the exchange of blood oxygen in patients, so we should actively treat the primary disease.