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

Rationale: 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.

Objectives: The study explores the impact of non-invasive ventilation (NIV) and ECCO₂R on respiratory drive, effort and distribution of ventilation in AECOPD.

Methods: 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.

Measurements and main results: 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), p < 0.0001), increased work of breathing (7.43 (6.08-10.19) vs. 11.1 (8.11-15.15) J/min, p < 0.0001) and increased neural drive (884.4 (684.7-967.3) vs. 1321.1 (903.3-1575.3) AU, p = 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, p < 0.0001), minute ventilation was higher (15.54 (13.14-18.48) vs. 12.24 (8.51-13.9) L/min, p < 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, p = 0.5556).

Conclusions: 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.

Trial registration: Clinicaltrials.gov; NCT02086084; registered 1 December 2015; https://clinicaltrials.gov/study/NCT02086084?cond=copd&term=ecco2r&rank=4.