Trial Information

Ischemic Conditioning (Delay Phenomenon) in Colorectal Surgery

This study is designed to evaluate the safety and feasibility of ischemic conditioning of
the colon prior to resection. Colon and rectal resections require the removal of a section
of colon or rectum with re-attachment (anastomosis) of the two ends. This joining together
of the intestine is at risk for leaking if healing does not occur appropriately. Factors
postulated to lead to anastomotic leak include ischemia as well as tension and infection
among others.

The concept of ischemic conditioning is based upon the innate ability to compensate and
increase the blood flow to a section of the intestine which is locally ischemic. By
inducing ischemia to a segment of intestine prior to resection, one could theoretically
increase blood flow via collateral vessels prior to resection. This would then, in turn,
lead to more initial blood flow to an anastomosis at the time of surgery via these
collaterals, thereby decreasing ischemia to a new, healing anastomosis.

Ischemic conditioning was first described in animal models proving its safety and efficacy.
In the rat model, ischemic conditioning demonstrated a return to baseline of tissue
perfusion by the time of resection, improved anastomotic leak rate and higher anastomotic
wound breaking strength. The first time this idea was implemented in the human model was in
a study by Akiyama et. al. where preoperative embolization was shown to be safe and improved
blood supply to the distal end of anastomosis after esophagectomy (remaining stomach).
Further basic science studies have shown improved angiogenesis, vasodilation, less
anastomotic collagen deposition and minimized ischemic injury. Further clinical studies
demonstrated improved stricture rates (0% from 40%), leak rates (0-6% from 5-15%) and
mortality (0% from 5-10%).

One of the major complications in colon and rectal surgery is improper healing of the
anastomosis (connection between the remaining, cancer free rectum with the remaining colon).
This results in an anastomotic leak or dehiscence leading to abscess, abdominal sepsis
requiring longer hospital stays, IV antibiotics, reoperation or possibly even death. It can
also lead to the late complication of stricture impairing function and often requiring
repeat dilations or operative revision. Recent reviews show rates of anastomotic
complications in upper rectal resection at 8-17% for leaks, and an average hospital stay of
10 days.

In the current study, preoperative embolization of the Inferior Mesenteric Artery (IMA) is
performed for patients scheduled to undergo colon or rectal resection. The surgery is then
performed in the standard fashion (either laparoscopically or open) several days later (1-5
days). The study is designed as a prospective, non-randomized, safety (pilot) study. Since
there are no reports of performing this exact procedure, we feel it is necessary to
initially proceed with safety study without a comparative arm prior to a large scale,
multicenter trial evaluating outcomes. Therefore, in this study we will not be evaluating
morbidity or mortality outcomes to any statistical significance.