 Noninvasive ventilation represents the standard of care for patients with exacerbation of chronic obstructive pulmonary disease. However, NIV fails in almost 30 of the most severe forms of acute hypercapnic respiratory failure and patients must undergo endotracheal intubation and invasive ventilation to restore adequate gas exchange. Under these circumstances, patients may express a clear intention not to be intubated.The aim of this study is to retrospectively assess efficacy and safety of noninvasive ventilation- plus-extracorporeal Co2 removal in patients who fail NIV and refuse endotracheal intubation. 