Continuous real-time viability assessment of kidneys based on oxygen consumption

Background: Current ex vivo quality assessment of donor kidneys is limited to vascular resistance measurements and histological analysis. New techniques for the assessment of organ quality before transplantation may further improve clinical outcomes while expanding the depleted deceased-donor pool. We propose the measurement of whole organ oxygen consumption rate (WOOCR) as a method to assess the quality of kidneys in real time before transplantation. Methods: Five porcine kidneys were procured using a donation after cardiac death (DCD) model. The renal artery and renal vein were cannulated and the kidney connected to a custom-made hypothermic machine perfusion (HMP) system equipped with an inline oxygenator and fiber-optic oxygen sensors. Kidneys were perfused at 8°C, and the perfusion parameters and partial oxygen pressures (pO₂) were measured to calculate WOOCR. Results: Without an inline oxygenator, the pO ₂ of the perfusion solution at the arterial inlet and venous outlet diminished to near 0 within minutes. However, once adequate oxygenation was provided, a significant pO₂ difference was observed and used to calculate the WOOCR. The WOOCR was consistently measured from presumably healthy kidneys, and results suggest that it can be used to differentiate between healthy and purposely damaged organs. Conclusions: Custom-made HMP systems equipped with an oxygenator and inline oxygen sensors can be applied for WOOCR measurements. We suggest that WOOCR is a promising approach for the real-time quality assessment of kidneys and other organs during preservation before transplantation.