Renal oxygenation during robot-assisted laparoscopic partial nephrectomy: Characterization using laparoscopic digital light processing hyperspectral imaging

Background and Purpose: Digital light processing-based hyperspectral imaging (DLP^®-HSI) was adapted for use during laparoscopic surgery by coupling the spectral illumination source with a conventional laparoscopic light guide and incorporating a customized digital charge-coupled device camera for image acquisition. The system was used to characterize renal oxygenation during robot-assisted laparoscopic partial nephrectomy (RALPN) in humans. Patients and Methods: After Institutional Review Board approval, laparoscopic DLP-HSI was performed in consecutive patients undergoing RALPN at our institution. Time trends in relative tissue oxygen saturation (%HbO ₂) were descriptively analyzed. Associations between %HbO₂ and patient age, comorbidities, and estimated glomerular filtration rate (eGFR) were investigated using the Kendall tau test. Results: Laparoscopic DLP-HSI was performed in 18 patients between May 2011 and February 2012. Median (interquartile range; IQR) age was 55.9 (49-67.5) years. Of the patients, 10/18 (56%) were men and 12/18 (66.7%) had a history of hypertension, diabetes, and/or tobacco use. Median (IQR) %HbO₂ before, during, and after ischemia was 60.8% (57.9-68.2%), 53.6% (46.8-55.1%), and 61.5% (54.9-67.6%), respectively. Baseline %HbO₂ was inversely associated with preoperative eGFR (τ=-0.38; P=0.036), and eGFR at most recent follow-up (τ=-0.38; P=0.036). Baseline or ischemic %HbO₂ did not correlate with hypertension, diabetes, and/or tobacco history. Younger patients (<56 years) had a lower median baseline %HbO₂ (P=0.07) and a higher median preoperative eGFR (P=0.038), than their older counterparts. Conclusion: The laparoscopic HSI system successfully characterized dynamic changes in renal oxygenation during RALPN. Intraoperative laparoscopic HSI outcomes have the potential to predict postoperative individual kidney function.