ObjectiveTo explore the relevance of the ratio of pulmonary arterial diameter to aortic diameter exceeding one (PA:A>1) with brain natriuretic peptide (BNP) and inflammatory factor levels in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). MethodsFrom August 2013 to December 2013,95 inpatients with AECOPD in West China Hospital were divided into two groups according to the ratio of pulmonary arterial diameter to aortic diameter. The clinical data of the patients were collected. Meanwhile,arterial blood gas,plasma levels of BNP,C-reactive protein (CRP),and interleukin-6 (IL-6) within 24 hours were measured. ResultsThe plasma BNP level was 2005(483-4582)ng/L in the group with PA:A>1,and 404(137-1224)ng/L in the group with PA:A<1. There was significant difference in plasma BNP level between two groups (P<0.01). There was no significant difference in CRP or IL-6 level between two groups (P>0.05). ConclusionThe ratio of pulmonary arterial diameter to aortic diameter is correlated with BNP level in patients with AECOPD,but is not correlated with CRP or IL-6.