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

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) The reported incidence of AL after esophagectomy ranges from 5%-20%. The AL associated mortality ranges from 18-40% compared with an overall in-hospital mortality of 4-6%. 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. Indocyanine green angiography (ICGA) is a near infrared fluorescent (NIRF) perfusion imaging using indocyanine green (ICG). ICGA is a safe, easy and reproducible method for graft perfusion analysis, but it is not yet calibrated. The purpose of this study is to evaluate the feasibility of quantification of ICGA to assess graft perfusion and its influence on AL in patients after minimally invasive Ivor Lewis esophagectomy (MIE) for cancer.

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

ICG based angiography 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.

ICGA will be performed twice during standard esophagectomy: 30 minutes after the stomach graft creation and immediately before the esophagogastric anastomosis. stock dose of 25 mg ICG (Pulsion Medical Systems, Germany) will be diluted to 5 mg/mL with sterile water. An IV bolus of 0.5 mg/kg of ICG will be injected via a central venous catheter. Video data will be obtained with a charge-coupled device (CCD) camera fitted with a light-emitting diode emitting at a wavelength of 760mm (Visera® elite II, Olympus medical system corp, Tokyo, Japan). Images will be recorded starting immediately prior to injection until 3 minutes afterwards.

Advanced continuous hemodynamic monitoring during surgery will be performed using a PiCCO® (Pulse index Continuous Cardiac Output, Pulsion Medical Systems, Germany) catheter.

Systemic and local capillary lactate on blood samples Mitochondrial Respiratory activity analyses on biopsies at 3 region of interest (ROI) Pathological analyses of the biopsies at 3 ROI

An ICGA based cutoff point to predict anastomotic leakage and graft necrosis after esophageal reconstructive surgery.

quantitative analysis of the ICGA images. T inflow will be calculated based on time fluorescence curves, and correlated with anastomotic leakage and graft necrosis. This cutoff value will be an ICGA fluorescent intensity time measurement expressed in seconds.

The evaluation of ICGA as a quantitative perfusion imaging modality during gastric tube reconstruction.

First, intensity over time curves will be analysed in the regions of interest to generate quantitative values for maximal fluorescence intensity (I max), inflow time (T inflow), and outflow time (T outflow). For every patient a time intensity curve will be created and From that curve 3 quantitaive time measures will be extracted: for maximal fluorescence intensity (I max), inflow time (T inflow), and outflow time (T outflow). These 3 times will be expressed in seconds

Peroperative biopsies will be collected and analyzed. Four sections of the embedded material are examined using a Haematoxylin-eosin staining. A semiquantitive scoring based on presence of fibroblasts, polynuclear neutrophils, lymphocytes and macrophages will be used to evaluate the severity of the inflammation. Scoring system. Score 0 = normal mucosa Score 1: partial epithelial edema and necrosis Score 2: diffuse swelling and necrosis of the epithelium Score 3: necrosis with submucosal neutrophil infiltration Score 4: widespread necrosis and massive neutrophil infiltration and bleeding

All adverse events will be classified by the Clavien Dindo score and based on the ECCG international consensus for complications associated with esophagectomy guidelines.The list is a predefined by the ECCG and can be found in reference 32.

Anaphylactic adverse events (AE): discomfort, flushing, tachycardia, hypotension, dyspnoea, bronchial spasm, blushing, cardiac arrest, laryngeal spasm, and facial oedema. Urticarial AE: pruritus, urticaria Nausea. hypereosinophilia

Advanced continuous hemodynamic monitoring during surgery will be performed using a PiCCO® (Pulse index Continuous Cardiac Output, Pulsion Medical Systems, Germany). This will provide specific perfusion measurements as cardiac output expressed in liters per minute from the Pulse contour analysis and Thermo dilution analysis.

Advanced continuous hemodynamic monitoring during surgery will be performed using a PiCCO® (Pulse index Continuous Cardiac Output, Pulsion Medical Systems, Germany). This will provide specific perfusion measurements as Stroke Volume (SV) expressed in milliliter and stroke volume variation (SVV) to predict Volume responsivity by Pulse contour analysis and Thermo dilution analysis.

Advanced continuous hemodynamic monitoring during surgery will be performed using a PiCCO® (Pulse index Continuous Cardiac Output, Pulsion Medical Systems, Germany). This will provide specific perfusion measurements as pulse pressure (PP) expressed in millimeters of mercury (mmHg) and pulse pressure variation (PPV) to predict volume responsivity by Pulse contour analysis.

Inclusion Criteria: Pre- and intraoperatively Subjects ≥ 18 years and ≤ 75 years who are willing to participate and provide written informed consent prior to any study-related procedures. Subjects scheduled for elective minimally invasive Ivor Lewis esophagectomy Intrathoracic circular stapled esophago-gastric anastomosis Exclusion Criteria: Preoperatively Known hypersensitivity to ICG Female patients who are pregnant or nursing Participation in other studies involving investigational drugs or devices. Use of Avastin™ (bevacizumab) or other anti vascular endothelial growth factor (VEGF) agents within 30 days prior to surgery Intra-operatively Intra-operative findings that may preclude conduct of the study procedures Anastomosis performed differently than the standard of care Excessive bleeding (>500 ml) prior to anastomosis

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