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Revista Portuguesa de Pneumologia

Print version ISSN 0873-2159


DIAS, Ricardo Marques et al. Comparison between total lung capacity and residual volume values obtained by pletysmography and single breath methods with methane. Rev Port Pneumol [online]. 2006, vol.12, n.6, pp.659-667. ISSN 0873-2159.

We analyzed pulmonary function tests of twenty asthmatic patients from Gaffrée e Guinle University Hospital, classified according to Brazilian Guidelines for Asthma (2002), similar to GINA, into mild persistent or moderate (9) or severe (11) asthma. We obtained parameters from spirometry, plethysmograph(PL) and single breath technique for diffusion capacity (SB), with methane. Total lung capacity and residual volume were called TLCPL and RVPL when measured by pletysmography and TLCSB and RVSB when determined by single breath test. There were 13 women and 7 men with mean age of 47.6 years. The pulmonary dysfunction degree to FEV1/FVC was 58.8% with CI95=53.9 to 63.6. The mean values in litres for TLCPL (5.94) and RVPL (2.55) were significantly higher than for TLCSB (4.73) and RVSB (1.66). Multiple regression equations were determined for TLCPL e RVPL using only single breath values,TLCSB or RVSB, and spirographic parameters, with significant regression coefficients. However, the inclusion of spirometric parameters, except for FVC, did not improve the predicted capacity for the equations. Considering only the TLCSB, r2=0.79, the equation is: TLCPL=(TLCSB*1.025)+1.088, with EPE=0.64. The regression for RVPL, r2=0.23, is: RVPL=(RVSB*0.9268)+1.012. The results obtained after bronchodilation with 400 mcg of salbutamol did not improve the regression. We concluded that the SB technique did not obtain the same results as pletysmography for TLC and RV, but for TLC this difference can be predicted.

Keywords : Whole body pletysmography; pulmonary diffusion test (DLco); pulmonary volumes; pulmonary function tests; asthma.

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