This randomized controlled trial compares a novel optical technique against the standard of care for assessing tissue perfusion in gastrointestinal surgery. Participants are randomized to receive either intraoperative imaging photoplethysmography (iPPG) or indocyanine green (ICG) fluorescence imaging. In the ICG group, the fluorescence data are comprehensively analyzed in two distinct ways: (1) Qualitative Assessment: real-time visual interpretation of the angiogram flow by the operating surgeon; and (2) Quantitative Assessment: software-based analysis of fluorescence kinetics (e.g., time-to-peak, maximum intensity) to generate objective perfusion parameters. The study aims to determine the agreement between the iPPG-based evaluations and both the qualitative and quantitative dimensions of the ICG standard.
Adult patients (age ≥ 18 years).
Scheduled to undergo an elective gastrointestinal resection requiring a primary gastro-intestinal or entero-enteric anastomosis.
Able to understand and provide written informed consent.
Known hypersensitivity or allergy to indocyanine green (ICG), iodine, or any component of the ICG formulation.
Severe hepatic impairment (e.g., Child-Pugh Class C).
Pregnancy or lactation.
Emergency surgery.
Parallel
ICG fluorescence imaging technology
DrugThis intervention involves the intravenous injection of the fluorescent contrast agent Indocyanine Green (ICG), followed by imaging with a near-infrared fluorescence camera system. Upon illumination with near-infrared light, ICG in the bloodstream fluoresces, allowing for real-time visualization of blood flow and tissue perfusion (qualitative assessment). Additionally, the fluorescence intensity over time can be recorded for subsequent quantitative analysis of perfusion kinetics.
Imaging Photoplethysmography System
DeviceImaging photoplethysmography is a non-contact, camera-based optical imaging technique. This investigational system operates by detecting subtle modulations in optical signals associated with pulsatile blood volume changes in microvascular tissue. It utilizes a conventional video camera to capture these signals and generates real-time tissue perfusion maps without the need for any exogenous contrast agents. The system is designed to provide intraoperative guidance for assessing tissue viability during gastrointestinal anastomoses.
Incidence of Anastomotic Leak
Comparison of the rate of clinically significant anastomotic leak between the iPPG-guided group and the ICG-guided group. Anastomotic leak is defined as a full-thickness defect requiring radiological, endoscopic, or surgical intervention, as confirmed by an independent clinical events committee within 30 days postoperatively.
Incidence of Anastomotic Leak: Qualitative vs Quantitative ICG Assessment
Comparison of the rate of clinically significant anastomotic leak between patients whose intraoperative assessment was based on qualitative ICG imaging (surgeon's visual interpretation) versus those assessed with quantitative ICG parameters (software-based kinetic analysis). Anastomotic leak is defined as a full-thickness gastrointestinal defect requiring postoperative radiological, endoscopic, or surgical intervention, as confirmed by an independent adjudication committee. This analysis will be performed specifically within the cohort of patients randomized to the ICG arm.
Diagnostic Performance for Predicting Anastomotic Leak
To evaluate and compare the diagnostic accuracy of the intraoperative iPPG assessment versus the standard ICG assessment (including both qualitative and quantitative methods) in predicting the occurrence of a postoperative anastomotic leak. The perfusion assessment during surgery will be dichotomized as 'inadequate' or 'adequate'. Diagnostic performance metrics including Sensitivity, Specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV), and the Area Under the Receiver Operating Characteristic Curve (AUC-ROC) will be calculated for each modality against the clinical outcome of anastomotic leak.
Rate of Anastomotic Revision Based on Perfusion Assessment
To quantify and compare the immediate impact of perfusion assessment on surgical decision-making by recording the frequency at which the operating surgeon decides to revise the anastomosis (i.e., resect and re-anastomose the bowel segment) based solely on the intraoperative findings of either iPPG or ICG imaging. The revision rate will be calculated as the proportion of patients in each arm (iPPG and ICG) for whom the anastomosis was revised due to perceived inadequate perfusion.
Overall Postoperative Complication Rate
To comprehensively evaluate and compare the overall postoperative morbidity between the iPPG-guided group and the ICG-guided group. All complications occurring within 30 days after surgery will be recorded and graded according to the Clavien-Dindo classification system. This standardized system categorizes complications based on the level of intervention required for management, ranging from Grade I (any deviation from the normal postoperative course not requiring pharmacological/surgical intervention) to Grade V (death). The comparison will focus on the incidence of complications of Grade II and above.
Rate of Re-intervention
To compare the incidence of unplanned, procedure-related re-interventions between the iPPG-guided and ICG-guided groups. A re-intervention is defined as any subsequent surgical, endoscopic, or radiology-guided invasive procedure required to manage a complication related to the initial gastrointestinal resection and anastomosis (e.g., control of bleeding, drainage of an intra-abdominal collection, or repair of an anastomotic leak). Planned, staged procedures are excluded. The rate is calculated as the proportion of patients in each group undergoing at least one such re-intervention.
Surgeon Confidence Score
To quantify the surgeon's confidence in the adequacy of the anastomotic perfusion following the intraoperative assessment. Immediately after evaluating the perfusion with the assigned modality (iPPG or ICG) and before abdominal closure, the primary surgeon will rate their confidence on an 11-point numerical rating scale, ranging from 0 (no confidence in anastomotic viability) to 10 (absolute confidence in anastomotic viability). The mean confidence scores will be compared between the two study arms.
Time from Imaging to Decision
To compare the workflow efficiency between the iPPG and ICG assessment modalities. This measure records the time elapsed from the moment a clear, interpretable perfusion image is first available on the display to the moment the surgeon verbally communicates the final decision regarding the anastomosis (e.g., "proceed as is," "revise anastomosis," "create stoma"). The time is recorded in seconds for each assessed anastomosis.
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Saint Petersburg State University, Russia
Lead sponsor
Shandong Linglong Yingcheng Hospital
Collaborator
High-Tech Clinic Beloostrov
Collaborator
