Extracorporeal lung support for hypercapnic ventilatory failure

Abstract

Extracorporeal lung support can be achieved using extracorporeal membrane oxygenation (ECMO) and extracorporeal CO2 removal. The ECMO systems allow a total lung support, providing both blood oxygenation and CO2 removal. Unlike ECMO, extracorporeal CO2 removal refers to an extracorporeal circuit that provides a partial lung support and selectively extracts CO2 from blood. The concept of partial extracorporeal lung support by removing only CO2 without effect on oxygenation was first proposed in 1977 by Kolobow and Gattinoni, with the aim to reduce breathing frequency, ventilator tidal volumes, and inspiratory pressures, facilitating lung-protective ventilation. Patients with end-stage chronic lung disease can survive, while waiting for lung transplantation, only if treated with mechanical ventilation or extracorporeal lung support. ECMO has been considered a suitable approach as a bridge to lung transplantation for patients with advanced respiratory failure waiting for lung transplantation. Extracorporeal CO2 removal has been proposed for the treatment of COPD patients suffering from exacerbation to avoid invasive mechanical ventilation. The rationale is to combine the improvement of alveolar ventilation by using noninvasive ventilation with muscle unload provided by removing CO2 directly from the blood, using an extracorporeal device. Increasing attention has been given to the possibility of patients performing a variety of physical activities while receiving extracorporeal lung support. This is possible thanks to the continuous development of technology together with the customization of sedative protocols. Awake extracorporeal support is a specific approach in which the patient is awake and potentially cooperative while receiving ECMO. The present analysis aims to synthesize the main results obtained by using extracorporeal circuits in patients with respiratory failure, particularly in those patients with hypercapnia. Key words: extracorporeal membrane oxygenation; physiotherapy; respiratory insufficiency; critical illness; lung transplantation; survival; CO2. [Respir Care 2018;63(9):1174–1179. © 2018 Daedalus Enterprises].