Revista Portuguesa de Pneumologia (Dec 2007)
A importância do estudo da difusão alvéolo-capilar, como complemento da pletismografia, na avaliação funcional de fumadores The importance of diffusing capacity as a complementary study to plethysmography in smokers
Abstract
Foram estudados 194 casos de fumadores e ex-fumadores (. 1 UMA), de ambos os sexos e idades compreendidas entre os 20 e os 82 anos, tendo sido excluídos doentes detentores de patologias ou antecedentes profissionais de risco. Apresentavam grau variado de sintomatologia e exame pletismográfico normal, mas com valores anormais do factor de transferência alvéolo-capilar, determinados pelo método de single breath com CO (TLCO SB e TLCO/VA). Dos 194 casos avaliados, 136 (70,1%) tinham valores anormais de um ou dos dois parâmetros referidos. No tratamento estatístico da amostra (teste do qui-quadrado), a diferença da sensibilidade entre ambos os parâmetros foi significativa (p=0,0001). As eventuais limitações do método de avaliação usado (single breath) foram, no presente estudo, minimizadas (restrição ventilatória com capacidade vital 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.
