Objective: Chronic respiratory failure (CRF) is a syndrome defined by certain disturbances in arterial blood gases. Non-invasive mechanical ventilation (NIMV) is an increasingly used treatment modality in respiratory failure. The aim of this study was to investigate the long-term effects of NIMV on pulmonary function and survival of patients with CRF.
Methods: The study enrolled 170 CRF patients who it was decided should receive long-term home mechanical ventilation. Patients were stratified into two distinct groups - Group I (patients for whom NIMV was recommended and who had used it) and Group II (patients for whom NIMV was recommended at least 1 year ago but who had not used it for various reasons). Best arterial blood gas and pulmonary function test values in the year before the NIMV recommendation were obtained from patient records. The same tests were performed at least 1 year (1-5 years) after initiation of NIMV therapy in Group I patients and at least 1 year (1-5 years) after prescription of the device in Group II.
Results: In the assessments performed 1 year after NIMV recommendation, no difference was found between groups in terms of hospital admissions. However, in Group I, intra-group analysis showed a reduction in the number of hospitalizations 1 year after NIMV. A marked reduction in PaCO(2) level was found in Group I patients 1 year after NIMV therapy. Mean survival after NIMV recommendation was 40.27 +/- 3.56 months in Group I, and 27.35 +/- 3.68 months in Group II (log rank = 7.79; p = 0.005). It was found that survival time increased as duration of NIMV usage increased.
Conclusion: NIMV therapy has some important and significant benefits in patients with hypercapnic chronic respiratory failure. This study has some limitations in terms of patient selection, power analysis and survival analysis. To assess the effects of NIMV on mortality and pulmonary functions, the authors believe that there is need for prospective, controlled, multicentre studies with longer follow-up periods, improved adherence and novel ventilator modes and settings.