To assess the changes of diffusion capacity in different stages of COPD patients.
95 stable COPD patients were divided into 4 groups: Stage I, II, III and IV according to EFV1/FVC% and FEV1% values, each with 8, 47, 34, 6 patients respectively. The transfer factor of the lung for carbon monoxide (TLco), pulmonary membrane diffusion capacity (Dm) and pulmonary capillary blood volume (Vc) were measured with single breathing method.
TLco,Dm and Vc were decreased in all COPD groups, significant differences were found in stage II to Stage IV groups in comparison with those of the normal subject group. TLco and Dm were progressively decreased from stage I to stage IV while Vc were comparable among all stage groups.
Diffusion capacity was progressively impaired with the severity of COPD.
Diffusion capacity measurement is also a valuable approach for further understanding the entity of COPD.
Yaling Zhu, None.Groupnml/min/mm HgDmTLcoPredVcmlNormal subject4313.82±4.92100.25±16.2679.40±28.44COPD stage I811.97±4.0199.32±23.4856.68±16.54COPD stage II479.76±4.54**69.39±19.43**52.38±20.76**COPD stage III348.26±3.27**62.29±13.62**45.13±18.29**COPD stage IV64.74±1.66**43.60±10.24**53.62±34.64*Normal subject4313.82±4.92100.25±16.2679.40±28.44*
P<0.01 compared with normal subject group