Fluorescent Evaluation of Colorectal Anastamoses

The purpose of this study is to evaluate whether systemically injected ICG, when fluorescing in response to NIR illumination, can assist with the assessment of perfusion at a bowel anastomotic site. This finding may assist surgeons to minimize the occurrence of leaks at the anastomotic site following this surgical procedure. The present study is a preliminary investigation to determine if this imaging modality will yield information regarding perfusion that is likely to be clinically relevant and so determine if a larger, multi center trial that correlates perfusion to clinical outcome is warranted. The results of the present study will also assist in the design of a larger scale study. It is expected that a successful outcome to such a trial will result in less morbidity following laparoscopic colectomy.

Laparoscopic bowel surgery is indicated for colon cancer, rectal cancer, diverticulitis, inflammatory bowel disease (including ulcerative colitis or Crohn's disease) and infarcted bowel. Prophylactic colectomy is also indicated for certain forms of polyposis to mitigate the risk of progression to colon cancer. The portion of colon resected during a colectomy is dependent upon the nature of the disease and its location and extent. Traditionally, colectomy has been performed by means of laparotomy, a standard abdominal incision. In recent years, beginning in the early 1990s, there has been increasing interest in, and utilization of, minimally invasive techniques for surgical procedures involving the colon and rectum. Laparoscopic surgery involves the introduction of surgical instruments through a number (usually 2-3) of small incisions measuring about 10-12 mm each with visual guidance being provided by means of a camera attached to an endoscope introduced through a similarly small access port. Laparoscopic techniques offer numerous benefits including a decrease in postoperative pain, some improvement in time to tolerance of food and return of bowel function, shorter hospital stay and more rapid return to normal activity.

Irrespective of the type of procedure performed (open or laparoscopic), anastomotic leakage following colorectal resection and primary anastomosis is a major clinical problem. The incidence of intraperitoneal anastomotic leaks reported in the literature may be as high as 30%. Anastomotic leaks leads to increased length of hospital stay, and may progress to abscess formation, sepsis, multi organ failure and even death.

The cause of anastomotic leakage is multifactorial with the following factors appearing to impact upon leakage; adequacy of blood flow to the anastomosis, contamination, the presence of a pelvic drain, anastomotic tension, anastomotic technique and the distance from the anal verge . The present study will investigate the first factor listed above, adequacy of blood flow to the anastomosis. At present there is no reliable and easy-to-perform modality that can be used to assess adequacy of perfusion at the anastomosis during colorectal procedures. This study will investigate the potential for the SPY scope to fill this clinical need.

The SPY® Intraoperative Imaging System is cleared for use in Canada, Japan, Europe and the US. SPY was originally developed for applications in cardiac surgery and allows cardiac surgeons to visually assess bypass graft quality in real-time while the patient is still in the operating room. Subsequently, SPY has received clearance from the FDA for use in plastic and reconstructive surgery and in solid organ transplant.

The SPY Intraoperative Imaging System was originally developed for open surgical procedures using ICG, which is an approved drug. ICG is a fluorescent compound, which can be administered intravenously or intra-arterially. The dye absorbs light in the near infrared (NIR) region at 806 nm, and emits light at a slightly longer wavelength, 830 nm. When injected intravenously, ICG rapidly and extensively binds to plasma proteins and is confined to the intravascular compartment with minimal leakage into the interstitium under normal conditions. This property makes it an ideal agent for the acquisition of high quality images of the vasculature. Intraoperative images are acquired during the first pass of a bolus of ICG through the area of interest. The SPY System has been the subject of numerous peer reviewed publications demonstrating its safety and efficacy .

SPY scope, the endoscopic version of SPY, is an endoscopic visible (VIS) NIR imaging system consisting of:

• An endoscopic light source that provides illumination for visible light imaging and NIR fluorescence excitation to the endoscope via a flexible light guide
• Rigid endoscopes optimized for illuminating the field of view and transmitting images in the visible and NIR spectrum, and
• A high definition (HD) endoscopic camera system connected to the endoscope eyepiece and acquiring high resolution visible and NIR fluorescence images The ICG (25 mg per vial) will be reconstituted according to the manufacturer's instructions using the entire contents (10 ml) of the sterile diluent supplied, yielding a 2.5 mg/ml solution of ICG or using half of the diluent supplied (5 ml) yielding a 5 mg/ml solution.