慢性阻塞性肺疾病 (COPD)发展到后期由于缺氧逐渐加重 ,二氧化碳潴留 ,导致肺心病、呼吸衰竭、循环衰竭 ,严重影响病人的活动能力和生命质量。特别是那些FEV1小于预期值 30 %的病人 ,有 1/ 2将在 5年内死亡。而缺氧是导致所有这些表现的基础。对COPD分级Ⅲ级以上的病人长期家庭 Chronic obstructive pulmonary disease (COPD) to the late development due to gradual hypoxia, carbon dioxide retention, leading to pulmonary heart disease, respiratory failure, circulatory failure, seriously affecting the patient’s mobility and quality of life. Especially those with FEV1 less than 30% of expected, one in two will die within 5 years. And hypoxia is the basis for all of these manifestations. COPD patients with grade Ⅲ or higher long-term family