Abstract

CARDOSO, António Paes; FERREIRA, José Manuel Reis  and  SILVA, Álvaro Moreira da. The importance of diffusing capacity as a complementary study to plethysmography in smokers . Rev Port Pneumol [online]. 2007, vol.13, n.6, pp.763-774. ISSN 0873-2159.

This study comprised 194 male and female heavy smokers or ex-smokers (. 1 pack-year) aged between 20 and 82, whose symptoms varied. Cases were only selected from patients with normal whole-body plethysmography. Subjects with any significant pathology and occupational risk factors were excluded from the study. Varying degrees of symptoms were found and a range of results from normal plethysmography examination, with abnormal levels of alveolar-capillary transfer, determined by the single-breath method to analyse CO (TLCO and TLCO-VA) coefficients. Using the chi-square test for statistical analysis of the sample revealed a significant variation in sensitivity between both parameters (p=0.0001). Possible limitations of using the single-breath method, of were reduced in this study (ventilatory restriction withVital Capacity <1.5 litres) by the routine plethysmography results seen. Likewise, the presence of alterations in ventilatory distribution was, in principle, minimised by the absence of TLCsb/TLCplet values below 0.85% Conclusions: Normal plethysmography results in heavy or ex-smokers are not enough to confirm normal respiratory function, as a large percentage of cases present abnormalities in the alveolar-capillary transfer factor for CO. Alveolar limitation was considered not only anatomically, but also from a functional perspective.

Keywords : Alveolar-capillary transfer; single breath; plethysmography; smokers.

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