A bridge over troubled waters.

Lung transplantation (LTx) remains the only therapeutic strategy for the treatment of end-stage respiratory failure in selected patients [1,2]. However, clinical scenario of LTx is rapidly changing. Two aspects still characterize LTx in comparison with the transplant of other solid organs. First, only a limited number of lung grafts is considered suitable for transplant within the donors’ pool. Secondly, patients quickly deteriorating while on the waiting list cannot be bridged for long periods [3]. These limitations result in a long period and a high mortality rate on the waiting list. Different strategies have been proposed to overcome these problems. Among those, the ex vivo lung perfusion (EVLP) appears the most promising one. Several lung transplant centers have been implemented with an EVLP program worldwide. EVLP is applied to evaluate and eventually recondition marginal or even initially rejected grafts, allowing an increase of transplanted grafts with clinical results as good as those obtained with the use of “standard” lungs [4,5]. Despite the effect of such strategies, the mismatch between the request and the offer still remains and the donor/recipient matching plays a crucial role to achieve the optimal risk/benefit ratio after transplant. Rapidly deteriorating patients waiting for lung transplant can be supported with mechanical ventilation and/or extracorporeal lung support (by means of extracorporeal circulatory membrane oxygenation or CO2 removal devices) only for a limited period of time, and LTx remains the definitive therapy. Therefore, critically ill patients suffering from severe hypercapnic or hypoxic respiratory insufficiency represent a real challenge in LTx. Ethical and clinical concerns arise when lungs are transplanted in supported patients because of the higher risk of transplant failure directly related to the critical status of the recipient. On the other hand, emergency LTx represents the only survival chance for these patients. In addition, emergency transplantation can reduce the number of grafts employed for standard cases loosing the survival benefit of elective procedure. In the paper entitled “Extracorporeal CO2-removal as bridge to lung transplantation in life-threatening hypercapnia”, Schellongowski P. et al. [6] describe optimal results