[Correlation between oxygen uptake efficiency and exercise capacity in pulmonary hypertension patients]

To explore the characteristics of oxygen uptake efficiency (OUE) in patients with pulmonary hypertension (PH) and analyze the correlation between OUE and exercise capacity.

A total of 76 PH patients and 29 healthy controls at Shanghai Pulmonary Hospital between October 2010 and January 2014 were evaluated. All PH patients were classified into 4 groups according to the World Health Organization functional class (WHO-FC). Pulmonary function and cardiopulmonary exercise tests were performed in all subjects.

Compared with health control, the PH patients had lower forced vital capacity (FVC) of expected value (%pre), forced expiratory volume in one second (FEV(1))%pre and FEV(1)/FVC ((81.9 ± 15.5)% vs (88.6 ± 14.1)%, (75.0 ± 16.4)% vs (85.2 ± 17.2)% and (78.3 ± 9.3)% vs (88.3 ± 7.3)%, all P < 0.05). Compared with control group, there were also significant reductions in oxygen uptake efficiency slope (OUES), oxygen uptake efficiency plateau (OUEP) and OUE at the anaerobic threshold ((1.14 ± 0.42) vs (2.32 ± 0.34) (L/min)/lg (L/min), (27 ± 5) vs (37 ± 4) ml/L, (24 ± 6) vs (34 ± 5) ml/L, all P < 0.05). No significant differences existed in OUES, OUEP and OUE at the anaerobic threshold in PH patients between WHO-FC Iand WHO-FC II groups. There were significant differences in OUE among other groups (all P < 0.05). And OUES, OUEP and OUE at the anaerobic threshold were correlated positively with exercise tolerance in PH patients.

OUE significantly declines in PH patients compared with normal subjects and it is correlated positively with exercise capacity.