A new paradigm for lung-conservative total liquid ventilation

Background: Total liquid ventilation (TLV) of the lungs could provide radically new benefits in critically ill patients requiring lung lavage or ultra-fast cooling after cardiac arrest. It consists in an initial filling of the lungs with perfluorocarbons and subsequent tidal ventilation using a dedicated liquid ventilator. Here, we propose a new paradigm for a lung-conservative TIN using pulmonary volumes of perfluorocarbons below functional residual capacity (FRC). Methods and findings: Using a dedicated technology, we showed that perfluorocarbon end-expiratory volumes could be maintained below expected FRC and lead to better respiratory recovery, preserved lung structure and accelerated evaporation of liquid residues as compared to complete lung filling in piglets. Such UV below FRC prevented volutrauma through preservation of alveolar recruitment reserve. When used with temperature-controlled perfluorocarbons, this lung-conservative approach provided neuroprotective ultra-fast cooling in a model of hypoxic-ischemic encephalopathy. The scale-up and automating of the technology confirmed that incomplete initial lung filling during UV was beneficial in human adult-sized pigs, despite larger size and maturity of the lungs. Our results were confirmed in aged non-human primates, confirming the safety of this lung-conservative approach. Interpretation: This study demonstrated that TIN with an accurate control of perfluorocarbon volume below FRC could provide the full potential of TLV in an innovative and safe manner. This constitutes a new paradigm through the tidal liquid ventilation of incompletely filled lungs, which strongly differs from the previously known TIN approach, opening promising perspectives for a safer clinical translation. (C) 2019 The Authors. Published by Elsevier B.V.