Abstract

MARTINEZ FRAGA, Alejandro; SIVORI, Martín; DELGADILLO, Sergio  and  SAENZ, César. Importance to adjust computerized informed KCO in patients with low alveolar volume. Rev. amer. med. respiratoria [online]. 2011, vol.11, n.1, pp.6-10. ISSN 1852-236X.

The decrease of the Transfer Factor of the Lung for Carbon Monoxide (TLCO) and the Alveolar Volume (VA) is not uniform. Software of lung computed machine informs the carbon monoxide transfer coefficient TLCO/VA (KCO) by calculating the ratio without adjusting for that assumption. Objectives: To calculate KCO using a correction by the Stam´s equation (J Apply Physiol 1994), to compare the corrected KCO with the result informed by the software of Collins lung laboratory equipment, and to evaluate the impact of using different predictive tables of VA in the estimates of KCO. Materials: Consecutive patients with intersticial lung disease who attended the Lung Laboratory to perform the TLCO between January and June 2008 were included in the study. TLCO was performed according to ATS/ERS recommendations by the single-breath and Ogilvie methods. KCO was calculated by the software of Collins Plus/SQL System (1995 Warren Collins), and then recalculated by Stam´s equation. Only patients with less than 80% of VA predictive value were included. Results: 15 patients with interstitial lung disease were evaluated (age: 57.53 ± 12.93 years old, female: 66.66%). The mean VA was 3.55 ±0.83 L (64.33 ±11.56%) and the mean KCO informed by software was 4.17 ±1.31 ml/min/mmHg/L. The corrected KCO was 3.76 ±1.33 ml/min/mmHg/L (Δ 11.84 ±3.84, range: 6.82%-21.1%). It was observed a negative and lineal relation between %VA and Δ KCO corrected/informed (R₂= -0.99). The election of different tables of VA normal values distorts up to12% the individual values, but the corrected KCO is little modified (3%). Conclusion: When the VA is reduced, the correction of the KCO must be performed, to avoid on average a 12% overestimate. Other factors such as the election of VA predictive tables have little influence on the KCO correction.

Keywords : Carbon Monoxide Coefficient; TLCO; VA; KCO; TLCO/VA; DLCO.

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