Late-breaking abstract: Baseline factors and survival difference between normocapnia, compensated respiratory acidosis and decompensated respiratory acidosis in COPD exacerbation

Background Patients experiencing acute exacerbation of chronic obstructive pulmonary disease (AE-COPD) with decompensated respiratory acidosis are known to have poor outcomes in terms of recurrent respiratory failure and death. The outcomes of AE-COPD patients with compensated respiratory acidosis are not known. Methods and Objective We performed a prospective, single-centre, cohort study in patients with AE-COPD for one year, to compare baseline factors between groups with normocapnia, compensated respiratory acidosis and decompensated respiratory acidosis. Survival analysis was done to examine time to readmissions, life-threatening events and death. Results Compared with normocapnia, both compensated and decompensated respiratory acidosis are associated with lower FEV1 % , higher GOLD stage and higher BODE index and they have shorter time to life-threatening events (fig1). Comparing compensated and decompensated respiratory acidosis, there was no difference in FEV1 (% predicted), GOLD stage, BODE index, and time to life-threatening events. PaCO2 and previous use of non-invasive ventilation (NIV) in acute setting are predictive factors of future life-threatening events by multivariate analysis. Conclusions Comparing with normocapnia, both compensated and decompensated respiratory are associated with poorer lung function and at high risk of future life-threatening events. PaCO2 and past history of NIV use in acute settings were predictive factors for future life-threatening events. Compensated respiratory acidosis warrants special attention and optimisation of medical therapy as it poses risk of life-threatening events.