• Yoshio Nakahara, Hiroyuki Taniguchi, Tomoki Kimura, Yasuhiro Kondoh, Shinichi Arizono, Koichi Nishimura, Koji Sakamoto, Satoru Ito, Masahiko Ando, and Yoshinori Hasegawa.
• Department of Respiratory Medicine and Allergy, Tosei General Hospital, Seto, Japan.
• Respirology. 2017 Jan 1; 22 (1): 120-125.

Background And ObjectivePulmonary hypertension (PH) in COPD is associated with morbidity and mortality. Previous studies showed a relationship between resting hypoxaemia and PH, but little is known about the relationship between exercise hypoxaemia and PH in COPD without resting hypoxaemia.MethodsA retrospective observational study of COPD patients without resting hypoxaemia was conducted to evaluate the relationships between exercise hypoxaemia and pulmonary haemodynamics. Clinical characteristics, pulmonary function, blood gas analysis, 6-min walk distance (6MWD) and oxygen saturation of peripheral artery (SpO2 ) at the end of the 6-min walk test (6MWT) were reviewed. Correlation analysis and stepwise regression analysis were performed to identify the predictor of mean pulmonary artery pressure (mPAP).ResultsEighty-four consecutive patients with a mean predicted forced expiratory volume in 1 s (FEV1 ) of 47 ± 21% were evaluated. In univariate analysis, mPAP had negative correlations with age (r = -0.27, P < 0.05), arterial partial pressure of oxygen (PaO2 , r = -0.24, P < 0.05), % predicted forced vital capacity (FVC, r = -0.28, P < 0.05), % predicted FEV1 (r = -0.40, P < 0.001), FEV1 /FVC ratio (r = -0.33, P < 0.005), % predicted diffusion capacity for carbon monoxide (DLCO , r = -0.40, P < 0.001), 6MWD (r = -0.40, P < 0.001) and SpO2 at the end of the 6MWT (r = -0.74, P < 0.001). In stepwise regression analysis, SpO2 at the end of the 6MWT and 6MWD remained as independent predictors of mPAP (R2  = 0.60). In receiver operating characteristic (ROC) analysis, SpO2 at the end of the 6MWT presented an area under the curve of 0.896 for the prediction of PH, with a sensitivity of 0.86 and specificity of 0.84 for the cut-off point of 81%.ConclusionIn addition to 6MWD, exercise hypoxaemia indicates PH in patients with COPD without resting hypoxaemia.© 2016 Asian Pacific Society of Respirology.

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