Renal oxygenation during partial nephrectomy: A comparison between artery-only occlusion versus artery and vein occlusion

Background and Purpose: During partial nephrectomy (PN), artery-only (AO) occlusion may mitigate ischemia/reperfusion injury because of retrograde venous flow. Using digital light processing-hyperspectral imaging (DLP®-HSI), we compared renal oxygenation during AO vs artery and vein (AV) occlusion in patients undergoing PN. Patients and Methods: Thirty-seven patients who were undergoing complex open PN (median R.E.N.A.L. nephrometry of 8) at our institution underwent renal oxygenation assessment using DLP-HSI. Percent renal parenchymal oxyhemoglobin (%HbO₂) during AO vs AV occlusion was recorded and its correlation with postoperative estimated glomerular filtration rate (eGFR) was investigated using Pearson correlation. AO and AV occlusion was performed in 12 and 25 patients, respectively. Results: Comparing AO vs AV, mean ischemia time was 41 vs 35 minutes (P=0.02). The %HbO₂ at baseline was 73.6% vs 71% (P=0.23). After hilar occlusion, %HbO₂ quickly reached an "ischemic plateau" in both groups, with mean ischemic %HbO₂ measures of 59.7% vs 62.2% (P=0.19). In the AV group, a lower mean ischemic %HbO₂ was associated with lower eGFR at the most recent follow-up (r=0.46, P=0.02) and remained significant on multivariable analysis (odds ratio 2.31; 95% confidence interval 0.29-4.32; P=0.03). Conclusions: In this pilot clinical study, renal oxygenation profiles during PN as assessed by DLP-HSI were similar for AO vs AV occlusion. Significant retrograde venous oxygen delivery using an AO occlusion technique could not be demonstrated. There was also no renal functional advantage for AO occlusion in this population of difficult PN where prolonged ischemia times may have mitigated any advantage. Further study in cases with shorter ischemia times is warranted.