**1. Introduction**

Patients with obstructive lung diseases, such as asthma and chronic obstructive pulmonary disease (COPD), may experience acute exacerbations with severe hypercapnic respiratory failure. Hypercapnia results from acute worsening of expiratory flow limitation caused by the increased small airway resistance with consequent development of dynamic alveolar hyperinflation and intrinsic PEEP. In the most severe cases, these may be refractory to conventional therapies and mechanical ventilation, becoming life-threatening.

Extracorporeal carbon dioxide removal (ECCO2R) represents an attractive approach in this setting.

The last decade has seen an increasing interest in the provision of extracorporeal support for respiratory failure, as demonstrated by the progressively increasing number of scientific publications on this topic. In particular, remarkable interest has been focused on ECCO2R, due to the relative ease and efficiency in blood CO2 clearance granted by extracorporeal gas exchangers as compared to oxygen delivery (**Table 1**).

In recent years, new-generation ECCO2R devices have been developed. More efficient veno-venous (VV-ECCO2R) devices have become available and have replaced the arteriovenous approach, having the advantage of not requiring arterial puncture.

They offer lower resistance to blood flow, have small priming volumes, and have a much more efficient gas exchange [1] with relatively low extracorporeal blood flows


**Table 1.**

*ECMO and ECCO2R differences.*

(0.4–1 L/min). With ECCO2R the patient's PaCO2 is principally determined by the rate of fresh gas flow through the membrane lung [2]. These devices are now comparable to renal dialysis equipment, which is routinely used safely as standard care in ICU.

This approach has been the subject of many animal experiments and human case series demonstrating improved arterial CO2 and work of breathing [3–6].
