P1.188. Correlation Between ICG Fluorescence Angiography Kinetics and Tissue Oxygen Saturation Gradients During Gastric Conduit Perfusion Assessment

Abstract

Abstract Topic Esophageal Cancer: Surgical Treatment of Esophageal Cancer Background Poor gastric conduit perfusion is associated with post-esophagectomy anastomotic leak. Oxygen saturation imaging (OSI) can be used to demonstrate a snapshot assessment of perfusion as an alternative to fluorescent angiography. We hypothesized that fluorescence kinetics and oxygen saturation perfusion gradient (ΔStO₂) would provide similar gastric conduit information during esophagectomy. Methods Intraoperative perfusion assessment data was prospectively collected for patients undergoing esophagectomy at a single, high-volume, quaternary hospital. OSI data using a laparoscope (Fujifulm) were obtained at 4 distinct time points including baseline perfusion, ligation of short gastric arteries, ligation of the left gastric artery, and after gastric conduit preparation. Changes in perfusion during stepwise ligation were noted and final gastric conduit preparation was compared to the standard SPY © (Stryker) indocyanine green dye perfusion assessment, performed after conduit preparation. Changes in perfusion during stepwise ligation were noted and compared by t-test. SPY ingress slope and ingress peak fluorescence intensity were extracted from perfusion curves, while ΔStO₂ was defined as the difference in tissue oxygen saturation between the conduit base and tip. Continuous and categorical variables were summarized descriptively. Pearson correlation tested univariate relationships between SPY parameters and ΔStO₂, and linear regression assessed independent associations. Results A total of 23 patients were analyzed (mean age 62.9 ± 14.1 years, 74% male). Mean ΔStO₂ from conduit base to tip was –14.5 ± 12.2%, indicating a progressive decline in oxygen saturation distally. Mean SPY ingress slope was 21.4 ± 10.7 and ingress peak 181.7 ± 55.7. ΔStO₂ demonstrated no significant correlation with SPY ingress slope (r = 0.15, p = 0.48) or ingress peak (r = –0.01, p = 0.97). In multivariable linear regression, neither ingress slope (β = 0.56, p = 0.21) nor ingress peak (β = –0.09, p = 0.29) was independently associated with ΔStO₂ (R2 = 0.08). Conclusion SPY fluorescence ingress kinetics and oxygen saturation gradients represent distinct physiologic measures of gastric conduit perfusion. The absence of correlation between SPY and OSI parameters suggests that dye transit and hemoglobin oxygenation provide complementary, rather than overlapping, information regarding tissue viability. More data is necessary to determine if OSI can be used to predict the risk of leak.