RT Journal Article SR Electronic T1 Base excess, a marker of chronic hypercapnic respiratory failure and predictor of survival in COPD JF European Respiratory Review JO EUROPEAN RESPIRATORY REVIEW FD European Respiratory Society SP 194 OP 196 DO 10.1183/09059180.00010118 VO 15 IS 101 A1 Stephan Budweiser A1 RudolfA. Jörres A1 Theresa Riedl A1 Frank Heinemann A1 Michael Pfeifer YR 2006 UL http://err.ersjournals.com/content/15/101/194.abstract AB We studied the role of base excess (BE) as marker of chronic hypercapnia and survival in patients with chronic obstructive pulmonary disease (COPD) and chronic hypercapnic respiratory failure (CHRF). Moreover, it was investigated whether the effects of non-invasive positive pressure ventilation (NPPV) on CHRF were reflected in BE and survival. In 240 (160 without exacerbation) patients with COPD (mean±sd FEV1 30.7±9.7 %pred; PaCO2 56.9±9.9 mmHg) body-mass index (BMI), lung function, respiratory muscle function, blood gases and 6-minute walking distance (6-MWD) were assessed prior to initiation of NPPV. In addition, the changes of risk factors 6.3±2.9 months after initiation of NPPV were evaluated. Overall mortality during the follow-up time (26.0±24.5 months) was 34.6%. Deaths resulted predominantly from respiratory causes (65.1%); among those, respiratory failure was most frequent (85.2%). Univariate analysis revealed BMI, FEV1, maximal inspiratory pressure (PImax), inspiratory load (P0.1), haemoglobin, 6-MWD, hyperinflation (IC/TLC, RV/TLC), blood gases and BE to be associated (p<0.05 each) with prognosis. In multivariate analyses, however, only BMI, RV/TLC and BE turned out to be independent cross-sectional predictors (p<0.05). Kaplan-Meier analyses showed that BE had predictive value particularly in patients with BMI≥25 kg·m−2, RV/TLC≥70 % and PaCO2≥57 mmHg. Furthermore, changes of BMI, RV/TLC and BE (p<0.01) were associated with improved prognosis in severe hypercapnic COPD. In patients with COPD and CHRF, BE was a prognostic marker for mortality, that was independent from other factors, particularly PaCO2. In addition, reversal of CHRF was reflected in BE and appeared to have an impact on prognosis.