189: Regional saturation directed normothermic regional perfusion in donors undergoing circulatory determination of death

Introduction: Normothermic regional perfusion (NRP) is increasingly implemented in donors undergoing circulatory determination of death (DCDDs). As during extracorporeal membrane oxygenation (ECMO), the sweep gas flow (SGF) to the membrane lung (ML) is the major determinant of ML CO2 removal (VMLCO2). A SGF increase will decrease the ML gas outlet partial pressure of CO2 (PEMLCO2), increasing pressure gradient between blood and gas phase, so VMLCO2. Methods: We aimed to assess the feasibility and effectiveness of PEMLCO2 monitoring to assess VMLCO2 and guide SGF management during NRP. We used a conventional capnogram monitoring device (schematics and devices details in figure A) to assess both continuous “waveform” and numeric PEMLCO2 value. The formula to calculate VMLCO2 from PEMLCO2 has been previously described for ECMO (figure B). The partial pressure of CO2 in the blood exiting the ML (PPOST-MLCO2) was assessed at initiation and every 30 minutes; the PEMLCO2 value was used to adapt SGF between blood samples. The waveform was used to detect complications as condensation in the exhaust gas tubing. Results: We implemented continuous PEMLCO2 monitoring in 10 DCDDs undergoing abdominal NRP (native lungs did not undergo mechanical ventilation, so ML was the sole determinant of CO2 removal). Detailed data on PEMLCO2, SGF, PPOST-MLCO2, VMLCO2 are included in figure C-D. Conclusion: Non-invasive PEMLCO2 monitoring appears feasible, allowing for prompt SGF optimization if modified blood PCO2 is suspected between blood analyses, potentially improving NRP safety.