Prognostic value of intraoperative renal tissue oxygenation measurement on early renal transplant function.

Ischemia time is a prognostic factor in renal transplantation for postoperative graft function and survival. Kidney transplants from living donors have a higher survival rate than deceased donor kidneys probably because of shorter ischemia time. We hypothesized that measurement of intraoperative kidney oxygenation (μHbO(2) ) and microvascular perfusion predicts postoperative graft function. We measured microvascular hemoglobin oxygen saturation by reflectance spectrophotometry and microcirculatory kidney perfusion by laser Doppler flowmetry 5 and 30min after kidney reperfusion on the organ surface in 53 renal transplant patients including 19 grafts from living donors. These values were related to systemic hemodynamics, cold ischemia time (cit), early postoperative graft function and length of hospital stay. μHbO(2) improved 30 min after reperfusion compared to 5 min (from 67% to 71%, P < 0.05). μHbO(2) correlated with mean arterial blood pressure and central venous pH (P < 0.01). Most importantly, μHbO(2) was significantly higher in kidneys from living compared with deceased donors (74% vs. 63%) and in kidneys without vs. with biopsy-proven postoperative rejection (71% vs. 45%, P < 0.001). Finally, μHbO(2) correlated positively with cit and postoperative creatinine clearance and negatively with postoperative plasma creatinine, need for hemodialysis and length of hospital stay. Our results suggest higher oxygen extraction and thus oxygen demand of the grafts shortly after reperfusion. The intraoperative measurement of tissue oxygenation in kidney transplants is predictive of early postoperative graft function. Future studies should evaluate the potential effect of intraoperative therapeutic maneuvers to improve organ tissue oxygenation in renal transplantation.