Long term effects of non-invasive mechanical ventilation on pulmonary haemodynamics in patients with chronic respiratory failure

Background - It is not known whether long term nocturnal mechanical ventila tion (NMV) reduces pulmonary hypertension in patients with chronic respirat ory failure (CRF). Methods - Pulmonary haemodynamics, spirometric values, and gas exchange wer e studied in 33 patients requiring NMV due to CRF (20 with thoracic restric tion, 13 with chronic obstructive pulmonary disease (COPD)) at baseline and after 1 year of NMV given in the volume cycled mode. Patients with COPD al so received supplemental oxygen. Results - Long term NMV improved gas exchange while lung function remained unchanged. Mean pulmonary artery pressure at rest before NMV was higher in patients with thoracic restriction than in those with COPD (33 (10) mm Hg v 25 (6) mm Hg). After 1 year of NMV mean pulmonary artery pressure decrease d in patients with thoracic restriction to 25 (6) mm Hg (mean change -8.5 m m Hg (95% CI -12.6 to -4.3), p <0.01) but did not change significantly in p atients with COPD (mean change 2.2 mm Hg (95% CI -0.3 to 4.8)). Conclusions - Long term NMV in CRF improves pulmonary haemodynamics in pati ents with thoracic restriction but not in patients with COPD.