Ex-Situ Limb Perfusion System: 24hr Preservation of Limbs

Alvaro Rojas-Pena^1,2, Benjamin Bryner², Yao Nie², Cory Toomasian², Jeffrey Punch^1,2, Robert Bartlett², Kagan Ozer^2,3

¹General Surgery-Section of Transplantation, University of Michigan, Ann Arbor, MI, United States, ²General Surgery-Extracorporel Life Support Laboratory, University of Michigan, Ann Arbor, MI, United States, ³Orthopaedic Surgery, University Michigan, Ann Arbor, MI, United States

Limbs used for transplantation or re-implantation are cold stored for 6-9hr before re-attachment. However, anaerobic metabolism waste products are released after reperfusion affecting recipient outcomes. The goal of this study was to develop and test a 25°C ex-situ limb perfusion system (ELiPS) that improves limb viability prior to transplantation in a porcine model.

METHODS: Control group (n=2), limbs were amputated, flushed and cold-stored for 9-12hr, then transplanted. Study group (n=6), limbs were attached to ELiPS for 24hr using pressure-controlled perfusion (80-90mmHg) with a blood-derived perfusate (plasma + 10%RBC, no WBC) then transplanted. Reperfusion was monitored (12hr) in anesthetized recipients. ELiPS settings, perfusate gases and response to neuro-muscular stimuli were monitored. Biopsies were taken for histology.

RESULTS: Successful 24hr ELiPS was feasible in the study group. All parameters were normal at the end of ELiPS, except for lactate=12.8±1.4mmol/L (normal <2mmol/L). Average limb vascular resistance=1.3±0.27mmHg/(mL/min) –normal=<1mmHg/(mL/min)-. Throughout 12hr of transplantation, lactate levels in the recipient were normal, and response to neuro-muscular stimuli was positive in 40% of the limbs in the study group, compared to 0% in the control group. Weight gain at the end of reperfusion was >15% from baseline in the control group, compared to <10% in the study group. 

CONCLUSION: 24hr ELiPS perfusion, followed by transplantation is feasible in this animal model. Lactate levels increased throughout ELiPS, but normalized after reattachment. Future directions include, adding hemodialysis to the ELiPS (lactate clearance), perfusate oncotic pressure (edema) and long-term sterility.

Figure 1

Figure 2