[Extracorporeal CO2 Elimination (ECCO2R) for Hypercapnic Respiratory Failure: From Pathophysiology to Clinical Application].

Extracorporeal CO2 removal (ECCO2 R) is becoming an increasingly established treatment option for patients with acute severe hypercapnic respiratory failure. Technically, pumpless arterio-venous systems using the natural arterio-venous pressure gradient and also pump-driven veno-venous systems are available. Here, veno-venous ECCO2 R has become the preferred technique, as settings for arterio-venous ECCO2 R are restricted and side effects are more common with arterio-venous ECCO2 R. Using veno-venous ECCO2 R with blood flow rates up to 450 ml/min 60 to 80 ml CO2 can be removed per minute corresponding to 20 to 30 % of the total amount of CO2 production. However, in case of very severe hypercapnic respiratory failure with severe respiratory acidosis (pH 7.1 or less) blood flow rates of around 1000 ml/min are required for compensating severe respiratory acidosis corresponding to the elimination of 50 to 60 % of the total amount of CO2 production. Relevant side effects include the activation of blood coagulation and associated bleeding complications. Two recent case-control studies in severely exacerbated COPD patients could demonstrate that intubation rates can be reduced by the application of ECCO2 R, but this was associated with non-ignorable side effects. Therefore, randomized controlled trials are urgently needed to more precisely establish the risks and benefits of ECCO2 R when aimed at avoiding intubation.