To investigate the role of the percentage of the total cross-sectional area of small pulmonary vessels for the lung area (%CSA) from high resolution computed tomography(HRCT)in chronic obstructive pulmonary disease (COPD) combined pulmonary hypertension(PH).

Twenty COPD combined PH patients and 20 normal subjects underwent chest HRCT scans and all data were analyzed retrospectively.COPD combined PH patients underwent pulmonary function tests (PFT), including forced expiratory volume in one second (FEV1%) and FEV1/forced vital capacity (FEV1/FVC), respectively.The %CSA less than 5 mm² and 5~10 mm² for the lung area (%CSA<5 and %CSA5~10) of small pulmonary vessels were measured with HRCT.Comparison of %CSA<5 and %CSA5~10 between the COPD combined PH and control groups were performed using t test.The correlation between % CSA and PFT was evaluated by the Spearman rank correlation test.

%CSA<5 of COPD combined PH patients and control group were (1.04±0.20)%、(0.82±0.14)%, respectively, the difference was statistically significant.%CSA5-10 of the two groups were (0.53±0.13)%、(0.33±0.08)% the difference between the two groups was significant. (t=5.41, P<0.01). FEV1% and FEV1/FVC in COPD patients were(32.40±11.31)% and (44.10±18.30)%.%CSA<5 in COPD patients were not correlated negatively with both FEV1% and FEV1/FVC (r=-0.136, -0.149; P>0.05). %CSA5~10 in COPD patients were not correlated negatively with both FEV1% and FEV1/FVC (r=-0.084, -0.724; P>0.05).

%CSA<5 and %CSA5~10 of COPD combined PH patients are higher than those of normal, they can be used as an index reflecting the severity of COPD combined PH.