Extra-corporeal CO2 Removal as an Adjunct to Non-Invasive Ventilation in Acute Severe Exacerbations of COPD

Chronic obstructive pulmonary disease (COPD) is one of the UKs commonest chronic diseases and is responsible for a significant number of acute hospital admissions. COPD is characterised by progressive destruction in the elastic tissue within the lung, causing respiratory failure. The clinical course of COPD is characterised by recurrent acute exacerbations (AECOPD), causing considerable morbidity and mortality. Patients with moderate to severe acute exacerbations present with increased work of breathing and hypercapnia. The standard for respiratory support in this setting is non-invasive ventilation (NIV), a management strategy underpinned by a considerable evidence base. However despite NIV, up to 30% of patients with AECOPD will 'fail' and require intubation and mechanical ventilation. The mortality rate for patients requiring NIV is approximately 4%, if conversion to mechanical ventilation occurs the mortality is 29%.

The last decade has seen an increasing interest in the provision of extracorporeal support for respiratory failure. The key element that has underpinned improving survival has been technological advancement. This has resulted in pumps causing less blood trauma and inflammatory response, better percutaneous cannulation techniques and coated circuits with reduced heparin requirements. Overall this has significantly reduced the complications associated with the provision of extracorporeal support. One variation of this technique (extra-corporeal CO2 removal ECCO2R) allows CO2 clearance from the blood. This approach has been the subject of a number of animal experiments and uncontrolled human case series demonstrating improved arterial CO2 and reduced work of breathing. Our own unpublished series demonstrates the same physiological changes. However to date the benefits of this approach have not been tested in a randomised controlled trial.

The hypothesis is that the addition of ECCO2R to NIV will shorten the duration of NIV and reduce likelihood of intubation.