Is University of Wisconsin (UW) solution superior to Histidine-Tryptophan-Ketoglutarate (HTK)-N solution for kidney preservation?

UW Solution is Superior to HTK-N for Kidney Preservation

University of Wisconsin (UW) solution is superior to Histidine-Tryptophan-Ketoglutarate (HTK)-N solution for kidney preservation, particularly for prolonged cold ischemia times. While both solutions demonstrate efficacy, the evidence indicates that UW solution provides better outcomes in terms of graft function and survival.

Comparative Efficacy of Preservation Solutions

• UW solution is considered the standard preservation solution for organ transplantation, with established efficacy in kidney preservation 1, 2
• When compared directly with HTK solutions, UW solution demonstrates advantages in several key outcomes:
  • More rapid reduction in postoperative serum creatinine 1
  • Higher creatinine clearance rates 1
  • Less postoperative dialysis requirement (21% vs 31%) 1
  • Better tissue ATP/ADP concentrations prior to transplantation 3

Performance in Prolonged Cold Preservation

• For kidneys with prolonged cold ischemia times (>24 hours), UW solution shows particular advantages:
  • Better preservation of high-energy phosphates 3
  • Improved survival rates compared to HTK-only preservation 3
  • Lower rates of initial non-functioning kidneys (75% vs 100% for HTK-only) 3

Modified HTK Solutions (HTK-N)

• While HTK-N was designed as an improvement over standard HTK solution, comparative studies have not demonstrated clear superiority over UW solution 4
• In a porcine model with 30-hour preservation time, HTK-N showed preservation efficacy comparable to UW, but not superior 4
• The theoretical advantages of HTK-N have not translated to clinically significant improvements in outcomes compared to UW solution 4

Combined Preservation Approach

• Interestingly, a combined approach using HTK for initial flush followed by storage in UW solution may provide superior results compared to either solution alone:
  • Higher survival rates (18.5 ± 4.6 days vs 13 ± 4.4 days for UW-only) 3
  • Lower rates of initial non-functioning kidneys (33% vs 75% for UW-only) 3
  • Better cellular energy conservation 3
  • Decreased free radical production 3

Clinical Considerations for Preservation Solution Selection

• For standard kidney preservation, UW solution remains the gold standard 1, 2
• For situations requiring prolonged cold ischemia time (>24 hours), UW solution is particularly advantageous 3, 2
• When using pulsatile perfusion, both UW and HTK solutions appear to have similar efficacy 5
• For marginal donor organs, the combined HTK flush with UW storage approach may provide optimal preservation 3

Importance of Preservation for Residual Kidney Function

• Proper preservation is critical for maintaining residual kidney function (RKF), which has significant benefits for patient outcomes 6
• Preservation of RKF contributes to:
  • Lower dialysis dose requirements 6
  • Improved patient survival 6
  • Reduced need for dietary potassium and fluid restriction 6
  • Enhanced quality of life 6

In conclusion, while both UW and HTK-N solutions demonstrate efficacy in kidney preservation, the evidence supports UW solution as superior, particularly for prolonged preservation times. The combined approach of HTK flush with UW storage may represent an optimal strategy for kidney preservation, especially for marginal organs.