[Effects of home oxygen therapy on pulmonary hemodynamics in patients with chronic obstructive pulmonary disease]

The aim of the study was to assess effects of long-term oxygen therapy (LTOT) on pulmonary haemodynamics in patients with chronic obstructive pulmonary disease (COPD). 93 pts (73M, 20F) mean age 58 years, entered the study. Their functional characteristics at entry for LTOT revealed: VC 2.33L, FEV1, 0.85L, FEV1/VC 37%, PaO2 55.5 mmHg, PaO2 46.7 mmHg, Hct 50%. Pulmonary haemodynamics showed: mild pulmonary hypertension (mean pulmonary arterial pressure PPA 25.9 mmHg), normal pulmonary wedge pressure (Pw) and increased driving pressure (PPA-Pw) 17.8 mmHg. Cardiac output (CO) was normal and pulmonary vascular resistance (PVR) averaged 313 dyne.s.cm-5. All enrolled patients were treated with oxygen at home and followed-up for at least 2 years. After 2 years of LTOT PPA and Pw fell by 2.4. and 2.6 mmHg, respectively, and (PPA-Pw) remained stable. An increase in CO by 0.31.min-1 was found while PVR was stable. After 4 years of treatment PPA, (PPA-Pw) and CO increased by 1.5, 1.7 mmHg and 0.9 l.min-1 respectively, while Pw and PVR remained stable. In 12 six years survivors PPA decreased after 2 years by 4.4 mmHg and cardiac output increased by 2 l.min-1 both returning to baseline after 6 years of LTOT. No significant changes in PVR were observed. Comparison of lung function tests before and after 6 years of LTOT showed deterioration of airways obstruction and of respiratory failure. LTOT for 14 h/d results in long-term stabilization of the hypoxic pulmonary hypertension despite of the progression of the natural course of COPD.