System Set-up for manual method
EVLP with STEEN Solution™ is a method to assess lung viability of donated lungs. EVLP aims to expand the potential donor pool, by increasing the time for the clinician to access the lungs in a near physiologic environment.
In order to evaluate an organ in an ex vivo system the STEEN Solution™ must be circulated through the organ via an extracorporeal perfusion circuit that allows continuous flow of nutrients and gas at a rate set by the clinician.
The circuit (see figure 1) allows fine targeted of organ temperature, left atrial pressure, pulmonary arterial pressure, venous PaO2and PaCO2. Which are targeted in a protocolized manner.
Included in the circuit, the heat exchanger and oxygenator is connected to the pulmonary artery of the lung to allow the perfusate to assume the temperature and partial gas pressures of normal venous blood. A leucocyte filter is connected in the attempt to prevent recirculation of activated leucocytes into the circuit and the lung. A membrane oxygenator is employed with both pre- and post- “membrane exchanger” gases being monitored; membrane gas flow varies according to phase of evaluation and technique employed. A standard ventilator is connected via an endotracheal tube secured in the trachea. The lungs are placed in the Organ Chamber™, a dome devised to maintain humidity.
The STEEN Solution™ is a buffered extracellular solution that includes human albumin to provide an optimal colloid osmotic pressure and dextran 40 to coat and protect the endothelium from excessive leucocyte interaction.
STEEN Solution™ is designed to facilitate prolonged evaluation and promote stability of isolated lungs ex vivo.
Hardware requirements for an EVLP procedure are generally off-the-shelf standard cardiac bypass equipment and include the following items:
- Centrifugal Pump and flow sensor
- Heater-cooler unit
- Vital signs monitor
- Gas analyser (either online or by solution sampling)
- Cylinder with O2 100% and Cylinder of CO2 7% – N 93% (Lund method)
- Cylinder containing O2 6%, CO2 8% and N2 86% (Toronto method)