Minimizing Abdominal Adhesions

Small intestinal strangulation or distension colic can produce ischemia (lack of blood flow), depriving tissues of oxygen and nutrients. As blood flow is restored, known as reperfusion, newly circulating blood triggers several cellular reactions resulting in generation of oxygen radicals and inflammation that promotes fluid and cellular leakage into surrounding tissue. This "reperfusion injury" can lead to postoperative complications, including ileus (intestinal obstruction), scarring, and adhesion formation (adhering of the resected intestine to nearby tissues). In an effort to minimize the damage caused by reperfusion injury, researchers from the Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, including Nathaniel White II, DVM, MS, Dipl. ACVS, designed a study to evaluate Carolina Rinse Solution (CRS), a product used to perfuse transplant organs, to decrease scar and adhesion formation after colic surgery.

During abdominal surgery on 11 horses, six were treated with CRS and five with lactated ringers solution (LRS) as a control. Briefly, a segment of jejunum (second portion of the small intestine) was isolated and vascular clamps were placed to slow, then stop, blood flow to the segment for a total of 120 minutes, mimicking an episode of colic. Near the end of this period, test horses were treated with CRS through a mesenteric artery into the isolated segment, while control horses were treated with the same volume of LRS. The solutions were also applied topically over the jejunal surface. "It took a few minutes to complete the perfusion of the CRS," explains White. "We began the process 10 minutes prior to releasing the vascular clamp, releasing it immediately after all the CRS was injected." After clamp release, reperfusion was allowed to occur for one hour. Biopsies were collected from the jejunum. Ten days later, the horses were euthanized and tissue samples collected.

Compared to the LRS group, CRS horses did not experience any significant increase in leakage of fluid from small blood vessels in the isolated segment after ischemia and reperfusion. Also, after 10 days, there was less microscopic evidence of scarring in CRS horses. Finally, there was a significant decrease in fibrous tissue at biopsy sites of CRS horses than LRS horses.

The authors caution that CRS could damage the mesenteric arteries. "During necropsy," says White, "the mesenteric arteries had evidence of scarring at the CRS catheter site." Therefore, CRS may work best as an intralumenal (within the intestine) and topical rinse.

White is currently completing work on a study evaluating analgesics for use in colic. Practitioners have been contributing data to this study via the Internet.

Dabareiner, R.M.; White, N.A. II; Donaldson, L. Equine Veterinary Journal, 35 (7): 642-646, 2003.

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