Physiological Assessment of ECCO₂R on the Work of Breathing in Exacerbations of COPD

The impact of extracorporeal carbon dioxide removal (ECCO₂R) on work of breathing and aeration in exacerbations of chronic obstructive pulmonary disease (AECOPD) is poorly understood. The study explores the impact of non-invasive ventilation (NIV) and ECCO₂R on respiratory drive, effort and distribution of ventilation in AECOPD. Patients enrolled in a randomised controlled study of the addition of ECCO₂R to NIV compared with NIV underwent oesophageal pressure measurement, electrical impedance tomography and parasternal electromyography. 18 patients were enrolled, nine in each arm. Of these, eight in the NIV arm and seven in the ECCO₂R arm underwent physiological assessment. Patients randomised to ECCO₂R, had a period of NIV combined with ECCO₂R and, after removal of NIV, a period of ECCO₂R alone. The removal of NIV whilst remaining on ECCO₂R resulted in a respiratory acidosis (pH 7.34 (7.31–7.34) vs. 7.31 (7.31–7.34), <i>p</i> &lt; 0.0001), increased work of breathing (7.43 (6.08–10.19) vs. 11.1 (8.11–15.15) J/min, <i>p</i> &lt; 0.0001) and increased neural drive (884.4 (684.7–967.3) vs. 1321.1 (903.3–1575.3) AU, <i>p</i> = 0.0005). On day 1, the work of breathing was lower in the NIV than the ECCO₂R group (4.38 (2.76–7.27) vs. 8.03 (4.8–15.94) J/min, <i>p</i> &lt; 0.0001), minute ventilation was higher (15.54 (13.14–18.48) vs. 12.24 (8.51–13.9) L/min, <i>p</i> &lt; 0.0001) and neural drive was the same (1,163.8 (1,085.5–1,325.5) vs. 1,093.8 (885.7–1,258.7) AU, <i>p</i> = 0.5556). The combination of NIV and ECCO₂R results in lower work of breathing and improved neuro-ventilatory coupling. NIV fully supports ventilation early whilst ECCO₂R improves neuro-ventilatory coupling and work of breathing over time. Clinicaltrials.gov; NCT02086084; registered 1 December 2015; https://clinicaltrials.gov/study/NCT02086084?cond=copd&amp;term=ecco2r&amp;rank=4