Urine Recirculation Improves Hemodynamics and Enhances Function in Normothermic Kidney Perfusion

Area of Science:

• Nephrology
• Transplantation
• Surgical Innovation

Background:

• Normothermic kidney machine perfusion (NMP) is a promising technique for organ preservation.
• Optimizing perfusate composition and stability is crucial for extending NMP duration.
• Current methods like urine replacement (UR) may have limitations in maintaining perfusate homeostasis.

Purpose of the Study:

• To compare urine recirculation (URC) with urine replacement (UR) using Ringer's lactate during porcine NMP.
• To evaluate the efficacy of URC in maintaining perfusate stability and facilitating long-term NMP.
• To assess the impact of cold ischemia time on the performance of URC and UR.

Main Methods:

• A preclinical prototype device was used in a porcine NMP model.
• Kidney pairs (n=10) were perfused with either URC or UR with Ringer's lactate.
• Perfusion parameters, biochemistry, and metabolic markers were monitored over up to 24 hours, with cold ischemia times of 2 or 27 hours.

Main Results:

• URC achieved sustainable physiological arterial pressures and flows, unlike UR.
• Significantly higher arterial flow (326.7 vs 242.5 mL/min) and lower perfusate lactate levels (2.2 vs 7.2 mmol/L) were observed with URC.
• URC facilitated longer perfusion durations (mean 17.3 hours vs 5.3 hours) and more physiological urine output (150 vs 548 mL/h).

Conclusions:

• Urine recirculation (URC) is essential for achieving long-term kidney NMP in a porcine model.
• Perfusate homeostasis and stable renal arterial flow were only achievable with URC.
• The benefits of URC were independent of cold ischemia time duration.