Minimal arterial in-flow protects renal oxygenation and function during porcine partial nephrectomy: Confirmation by hyperspectral imaging

Objectives: To examine the potential for renal protection through incomplete renal artery (RA) occlusion with both assessments of creatinine changes and the use of hyperspectral imaging to monitor tissue oxygenation. Renal ischemia during partial nephrectomy can have adverse consequences on renal function. Methods: Fourteen pigs with a solitary kidney underwent open partial nephrectomy with warm ischemia. The RA flow was measured and reduced to 25%, 10%, and 0% of baseline for 60 minutes. Hyperspectral imaging was used to assess the percentage of oxyhemoglobin (%HbO ₂) at baseline, during ischemia, and during reperfusion. The %HbO ₂ and change in the serum creatinine level from baseline were compared. Results: The baseline RA flow and %HbO ₂ were similar in all groups, and, as expected, RA occlusion resulted in decreasing %HbO ₂. The reduction of RA flow to 25% and 10% improved the nadir tissue oxygenation compared with 0% flow (P =.01 and P =.04, respectively) and 25% flow also appeared to prolong the interval to reach the nadir %HbO ₂. Reperfusion resulted in a swift return to the baseline %HbO ₂ in all 3 groups. The change in the serum creatinine from baseline to postoperative day 7 showed significantly improved renal preservation in the 25% RA flow group. Conclusions: Incomplete RA occlusion during porcine partial nephrectomy resulted in favorable renal oxygenation profiles with as little as 10% blood flow and appeared to be renoprotective when 25% of the baseline RA flow is preserved. Hyperspectral imaging is a sensitive, noninvasive tool for real-time monitoring of renal oxygenation and, thereby, blood flow, which could facilitate intraoperative decision-making to protect kidney function.