Evaluation of a novel laparoscopic camera for characterization of renal ischemia in a porcine model using digital light processing (DLP) hyperspectral imaging

Introduction: Digital light processing hyperspectral imaging (DLP (R) HSI) was adapted for use during laparoscopic surgery by coupling a conventional laparoscopic light guide with a DLP-based Agile Light source (OL 490, Optronic Laboratories, Orlando, FL), incorporating a 0(0) laparoscope, and a customized digital CCD camera (DVC, Austin, TX). The system was used to characterize renal ischemia in a porcine model. Methods: Laparoscopic DLP (R) HSI was performed in 2 groups of uni-nephric adult pigs that were each subjected to 90 minutes of warm ischemia. Group 1 (n=5) received tadalafil to mitigate ischemia/reperfusion injury while Group 2 (n=4) received no treatment. HSI-derived percentage of oxygenated hemoglobin (%HbO(2)) was plotted against time before, during and after ischemia. Serum creatinine measured pre-ischemia (D0), and on days 1, 3 and 7 post-ischemia, was correlated with %HbO(2) using the Spearman's rank test. %HbO(2) was compared for the groups using the Student's t-test. Results: Mean baseline and nadir %HbO(2) for tadalafil vs. controls was 74% vs. 75% and 50% vs. 54% respectively; values did not significantly differ between the groups at any sampled time point. D0 creatinine was significantly lower for the tadalafil group, but creatinine at all other time points was similar between the groups. Baseline and nadir %HbO(2) significantly correlated with D7 and D0 creatinine respectively in the tadalafil group alone. Conclusion: Laparoscopic DLP (R) HSI effectively characterizes renal ischemia, appears to be sensitive to changes in local blood flow, and is predictive of renal functional injury. Further parameterization and technological improvement is required before clinical incorporation.