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Effects of intraluminal distention and decompression on microvascular permeability and hemodynamics of the equine jejunum

Robin M. DabareinerMarion duPont Scott Equine Medical Center, Virginia- Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Leesburg, VA 20177.
Present address is Department of Large Animal Medicine and Surgery, College of Veterinary Medicne, Texas A&M University, College Station, TX 77843-8863.

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 DVM, MS
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Nathaniel A. WhiteMarion duPont Scott Equine Medical Center, Virginia- Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Leesburg, VA 20177.

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Lydia L. DonaldsonMarion duPont Scott Equine Medical Center, Virginia- Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Leesburg, VA 20177.

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 VMD, PhD

Abstract

Objective—To determine whether intraluminal distention and subsequent decompression of the equine jejunum affects intestinal blood flow, hemodynamics, and microvascular permeability.

Animals—5 healthy adult horses.

Procedure—Horses were anesthestized and underwent exploratory laparotomy. Two jejunal segments were identified as sham-operated or instrumented segments. After baseline values were obtained, intraluminal distention was created in the experimental segment to induce an intraluminal pressure of 18 cm H2O. After 120 minutes of distention, the intestine was decompressed for 120 minutes. Mesenteric blood flow, oxygen delivery, oxygen consumption, microvascular permeability, wet weight-to-dry weight ratio, neutrophil infiltration, and vascular resistance were determined and comparisons made among control, sham-operated, and experimental segments.

Results—Mean jejunal blood flow was 21.4 ml/min per kg. There was a significant decrease in mesenteric blood flow to the distended intestine (13.4 ml/min per kg). Blood flow increased significantly during the decompression period (340% of baseline blood flow). Intraluminal distention and subsequent decompression resulted in a significant increase in microvascular permeability, as determined by the osmotic reflection coefficient. Oxygen delivery and oxygen content decreased significantly during the distention period and increased during decompression. Morphologic evaluation revealed a significant increase in edema and neutrophil infiltration after distention and decompression, compared with results for the sham-operated or control segments.

Conclusions and Clinical Relevance—Intraluminal distention and decompression of the equine jejunum results in low-flow ischemia and edema, which may contribute to adhesions and ileus in the postoperative period after surgery for obstructions of the small intestines. (Am J Vet Res 2001;62:225–236)

Abstract

Objective—To determine whether intraluminal distention and subsequent decompression of the equine jejunum affects intestinal blood flow, hemodynamics, and microvascular permeability.

Animals—5 healthy adult horses.

Procedure—Horses were anesthestized and underwent exploratory laparotomy. Two jejunal segments were identified as sham-operated or instrumented segments. After baseline values were obtained, intraluminal distention was created in the experimental segment to induce an intraluminal pressure of 18 cm H2O. After 120 minutes of distention, the intestine was decompressed for 120 minutes. Mesenteric blood flow, oxygen delivery, oxygen consumption, microvascular permeability, wet weight-to-dry weight ratio, neutrophil infiltration, and vascular resistance were determined and comparisons made among control, sham-operated, and experimental segments.

Results—Mean jejunal blood flow was 21.4 ml/min per kg. There was a significant decrease in mesenteric blood flow to the distended intestine (13.4 ml/min per kg). Blood flow increased significantly during the decompression period (340% of baseline blood flow). Intraluminal distention and subsequent decompression resulted in a significant increase in microvascular permeability, as determined by the osmotic reflection coefficient. Oxygen delivery and oxygen content decreased significantly during the distention period and increased during decompression. Morphologic evaluation revealed a significant increase in edema and neutrophil infiltration after distention and decompression, compared with results for the sham-operated or control segments.

Conclusions and Clinical Relevance—Intraluminal distention and decompression of the equine jejunum results in low-flow ischemia and edema, which may contribute to adhesions and ileus in the postoperative period after surgery for obstructions of the small intestines. (Am J Vet Res 2001;62:225–236)