Indocyanine green fluorescence in second-look surgery for necrotizing enterocolitis -enhancing the surgeon's perception

Antonia Maximina Pfennigs^1*Manuel Besendörfer^2,3Sonja Diez^2,3Bertram Reingruber¹

• ¹Florence Nightingale Hospital Kaiserswerther Diakonie, Düsseldorf, Germany
• ²Friedrich-Alexander-Universitat Erlangen-Nurnberg, Erlangen, Germany
• ³Universitatsklinikum Erlangen, Erlangen, Germany

Abstract Background: A perfusion mismatch in the premature gut is the key component in the development of necrotizing enterocolitis (NEC). Resulting necroses need to be surgically excised while intestinal salvage is crucial to the survival and rehabilitation of affected preterm neonates. Until now, resection margins have been based on standard visual inspection and surgical experience since objective criteria for bowel viability are lacking. We hypothesize that by evaluation of vitality and perfusion during NEC surgery, margins of necrosis can reliably be defined by Indocyanine Green (ICG) fluorescent imaging, a real time visualization method, which has already been implemented safely in pediatric surgery for other indications. Materials and methods: In a prospective study at our Level 1 Perinatal Center, patients were recruited after primary emergency surgery confirming NEC. Due to the acute phase of the inflammatory process, the extent and the dynamics can usually not be clearly defined at this point. Informed consent of the parents for the second look surgery included fluorescent imaging and ICG (0.04-0.7 mg/kg body weight), which was applied after completely exposing the intestinal bundle to visualize blood perfusion intraoperatively. ICG perfusion of intestinal tissue was visualized by a near-infrared camera and was compared with bowel vitality as judged conventionally by an experienced surgeon. Upon those findings, further treatment was specified. We correlated our surgical findings with subsequent histopathology. Results: Six patients treated at our perinatal center met the inclusion criteria. In four cases, ICG-negative, non-vital gut areas were detected and resected with narrow margins of <1mm. Histology as well as the further medical course proved to be consistent with these intraoperative results. In two cases, the clinical appearance of complete necrosis of the small intestines was confirmed by ICG, supporting the decision to provide palliative treatment. In two out of six cases, clinical judgment and real time ICG-fluorescence were contradictory. Here, histopathology confirmed complete necrosis of the bowel in full accordance with ICG. Conclusion: Our prospective cohort study gave evidence for ICG-fluorescence being useful and reliable to objectify blood perfusion and intestinal vitality during NEC surgery, adding objectiveness to the surgeon’s personal experience.