Elevated blood lactate in <scp>COPD</scp> exacerbations associates with adverse clinical outcomes and signals excessive treatment with β<sub>2</sub>‐agonists
Martin MacDonald, Kevan R. Polkinghorne, Chris MacDonald, Paul Leong, Kaïs Hamza, Gayan Kathriachchige, Christian Osadnik, Paul T. King, Philip G. Bardin
Abstract
Abstract Background and Objective Raised blood lactate secondary to high dose β 2 ‐agonist treatment has been reported in asthma exacerbations but has not been investigated during acute exacerbations of COPD (AECOPD). We explored associations of blood lactate measurements with disease outcomes and β 2 ‐agonist treatments during AECOPD. Methods Retrospective ( n = 199) and prospective studies ( n = 142) of patients hospitalized with AECOPD were conducted. The retrospective cohort was identified via medical records and the prospective cohort was recruited during hospitalization for AECOPD. Baseline demographics, comorbidities, β 2 ‐agonist treatment, biochemical measurements and clinical outcomes were compared between patients with normal (≤2.0 mmol/L) versus elevated lactate (>2.0 mmol/L). Regression analyses examined associations of lactate measurements with β 2 ‐agonist dosages. Results Demographic data and comorbidities were similar between high versus normal lactate groups in both cohorts. The populations were elderly (mean >70 years), predominantly male (>60%) with reduced FEV 1 (%) 48.2 ± 19 (prospective cohort). Lactate was elevated in approximately 50% of patients during AECOPD and not related to evidence of sepsis. In the prospective cohort, patients with high lactate had more tachypnoea, tachycardia, acidosis and hyperglycaemia ( p < 0.05) and received more non‐invasive ventilation (37% vs. 9.7%, p < 0.001, prospective cohort). There was a trend to longer hospitalization (6 vs. 5 days, p = 0.06, prospective cohort). Higher cumulative β 2 ‐agonist dosages were linked to elevated lactate levels (OR 1.04, p = 0.01). Conclusion Elevated lactate during AECOPD was common, unrelated to sepsis and correlated with high cumulative doses of β 2 ‐agonists. Raised lactate may indicate excessive β 2 ‐agonist treatment and should now be investigated as a possible biomarker.