Yoshio Nakahara1,2, Hiroyuki Taniguchi1, Tomoki Kimura1, Yasuhiro Kondoh1, Shinichi Arizono3, Koichi Nishimura4, Koji Sakamoto2, Satoru Ito2, Masahiko Ando5, Yoshinori Hasegawa2. 1. Department of Respiratory Medicine and Allergy, Tosei General Hospital, Seto, Japan. 2. Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan. 3. School of Rehabilitation Sciences, Seirei Christopher University, Hamamatsu, Japan. 4. Department of Pulmonary Medicine, National Center for Geriatrics and Gerontology, Obu, Japan. 5. Center for Advanced Medicine and Clinical Research, Nagoya University Hospital, Nagoya, Japan.
Abstract
BACKGROUND AND OBJECTIVE: Pulmonary 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. METHODS: A 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). RESULTS: Eighty-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%. CONCLUSION: In addition to 6MWD, exercise hypoxaemia indicates PH in patients with COPD without resting hypoxaemia.
BACKGROUND AND OBJECTIVE:Pulmonary 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. METHODS: A retrospective observational study of COPDpatients 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). RESULTS: Eighty-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%. CONCLUSION: In addition to 6MWD, exercise hypoxaemia indicates PH in patients with COPD without resting hypoxaemia.