RESUMEN
Long-term sequential evolution of pulmonary function, blood gas, body mass index (BMI) and oxygen breathing time was observed in 266 COPD patients with advanced airway obstruction (FEV1 = 0.80 L), and severe respiratory failure (PaO2 = 52 mmHg, PaCO2 = 49 mmHg) undergoing LTOT. There were significant differences between survivors and non-survivors at entry and during the treatment. Patients dying during LTOT had at entry lower BMI and more advanced airway limitation than survivors. They did not differ in blood gas values. During the follow-up (between 1-4 years) different trends in evolution of studied variables were observed in survivors (over 4 years on LTOT) and patients dying during LTOT (up to 4 years). Long term stabilization of spirometric and blood gas values as well as in mean oxygen breathing time (14 hours) were observed in survivors. In non-survivors a significant progression in airway limitation and respiratory failure coupled with better compliance with LTOT (oxygen use increased from 15 to 17 hours/ day) was observed especially in the last year before death. In survivors BMI increased significantly during the treatment, whereas in non-survivors no change was observed.