Assessment of Graft Perfusion and Oxygenation for Improved Outcome in Esophageal Cancer Surgery

Background: The incidence of adenocarcinoma of the esophagus is rapidly increasing, resulting in 480 000 newly diagnosed patients annually in the world1. Surgery remains the cornerstone of therapy for curable esophageal cancer (EC) patients. After the esophagectomy, the stomach is most commonly used to restore continuity of the upper gastro-intestinal tract. The esophagogastric anastomosis is prone to serious complications such as anastomotic leakage (AL), fistula, bleeding, and stricture. The reported incidence of AL after esophagectomy ranges from 5%-20% 2-6. The AL associated mortality ranges from 18-40% compared with an overall in-hospital mortality of 4-6% 2, 7, 8. The main cause of AL is tissue hypoxia, which results from impaired perfusion of the pedicle stomach graft. Clinical judgment is unreliable in determining anastomotic perfusion. Therefore, an objective, validated, and reproducible method to evaluate tissue perfusion at the anastomotic site is urgently needed. Near infrared fluorescent (NIRF) perfusion imaging using indocyanine green (ICG) is an emerging modality based on excitation and resulting fluorescence in the near-infrared range (λ = 700-900 nm).

Aims:

• To perform intraoperative ICG based NIRF angiography of the stomach graft during minimally invasive esophagectomy in EC patients, and to calculate tissue blood flow and volume using curve analysis and advanced compartmental modeling;
• To validate imaging based perfusion parameters by comparison with hemodynamic parameters, blood and tissue expression of hypoxia induced markers, and tissue mitochondrial respiration rate
• To evaluate the ability of NIRF based perfusion measurement to predict anastomotic leakage.

Methods: Patients (N=70) with resectable EC will be recruited to undergo minimally invasive Ivor Lewis esophagectomy according to the current standard of care. ICG based angiography will be performed after creation of the stomach graft and after thoracic pull-up of the graft. Dynamic digital images will be obtained starting immediately after intravenous bolus administration of 0.5 mg/kg of ICG. The resulting images will be subjected to curve analysis (time to peak, washout time) and to compartmental analysis based on the AATH kinetic model (adiabatic approximation to tissue homogeneity, which allows to calculate blood flow, blood volume, vascular heterogeneity, and vascular leakage). The calculated perfusion parameters will be compared to intraoperative hemodynamic data (PiCCO catheter) to evaluate how patient hemodynamics affect graft perfusion. To verify whether graft perfusion truly represents tissue oxygenation, perfusion parameters will be compared with systemic lactate as well as serosal lactate from the stomach graft. In addition, perfusion parameters will be compared to tissue expression of hypoxia related markers and mitochondrial chain respiratory rate as measured in tissue samples from the stomach graft.

Finally, the ability of functional, histological, and cellular perfusion and oxygenation parameters to predict anastomotic leakage and postoperative morbidity in general will be evaluated using the appropriate univariate and multivariate statistical analyses.

Relevance: The results of this project may lead to a novel, reproducible, and minimally invasive method to objectively assess perioperative anastomotic perfusion during EC surgery. Such a tool may help to reduce the incidence of AL and its associated severe morbidity and mortality