Mechanical circulatory support in lung transplantation: Cardiopulmonary bypass, extracorporeal life support, and ex-vivo lung perfusion

Figure 1 Cardiopulmonary bypass circuit is an open circuit in which venous blood drains into the venous reservoir by gravity (40-70 cm below the level of the heart) or siphonage. Cardiopulmonary bypass circuit is considered an open circuit: blood from the cardiotomy reservoir, blood transfusions, or other fluids may be added into the circuit. Blood then passes through an oxygenator or gas-exchanger and is returned to the arterial system by utilizing a roller or centrifugal pump[8]. Figure from Machin et al[8], with permission of Oxford University Press.

Figure 2 Schematic illustrating the components of an extracorporeal membrane oxygenation circuit: centrifugal pump, membrane oxygenator, inflow and outflow cannulas or cannula, and tubing with the potential to add ports for hemodialysis or ultrafiltration[9]. ECMO: Extracorporeal membrane oxygenation.

Figure 3 Extracorporeal lung assist, Interventional Lung Assist, or the NovaLung^® System. A: Flow measure across the system, in this case 1.77 L of blood per minute; B: Arterial and venous lines, oxygen inflow, and extracorporeal membrane made of polymethylpentene which provides gas exchange by simple diffusion; C: Exchange membrane and arterial and venous cannulations; D: AV cannulation diagram for extracorporeal lung assist, note the absence of a pump[32].

Figure 4 Only 15%-20% of donor organs meet standard criteria for lung transplant.