Systems and methods for ex vivo lung care

A method of preserving a lung ex vivo comprising:

• circulating a perfusion fluid through the lung, the fluid entering the lung through a pulmonary artery interface and leaving the lung through a left atrial interface;
• ventilating the lung through a tracheal interface by flowing a captive volume of a ventilation gas back and forth between the lung and a variable volume chamber;
• introducing into the captive volume an additional volume of the ventilation gas wherein the additional volume of the ventilation gas is about 10% of a tidal volume and venting excess ventilation gas from the captive volume using a pneumatic control system that controls at least a valve to maintain a predetermined composition of the ventilation gas and to maintain a minimum gas pressure of the captive volume;
• and
• wherein a gas exchange in the lung between a component of the ventilation gas and the perfusion fluid causes the corresponding gas component in the perfusion fluid to reach an equilibrium value.