Splanchnic Surface Oximetry during Experimental Portal Hypertension and Surgical Manipulation of Portosystemic Shunts in Dogs

Abstract

Surface oxygen tension (PSO2) was measured in dogs during experimental manipulation of the portal vein and hepatic artery, and during surgery to correct portosystemic shunting. There was no alteration in PSO2 of liver, pancreas, duodenum, or jejunum during partial (50%) or complete reduction of hepatic artery flow. After 100% reduction in portal vein blood flow, PSO2 was lower in jejunum, duodenum, and liver. With 50% reduction in portal flow, PSO2 was significantly decreased only in jejunum. In six dogs with single extrahepatic shunts, there was a significant correlation between portal pressure and jejunal PSO2. It was concluded that measurement of visceral organ PSO2 represents an accurate noninvasive means of obtaining objective data on the effect of reduction in hepatic blood flow on perfusion of other select splanchnic organs.

Liver Size, Bodyweight, and Tolerance to Acute Complete Occlusion of Congenital Extrahepatic Portosystemic Shunts in Dogs

“…Furthermore, application of the probe to the intestinal wall frequently resulted in a prolonged peristaltic response in the intestine adjacent to the probe, which is also likely to have affected tissue perfusion and thus oxygenation. Intestinal surface oximetry measurement has been identified as a potentially useful method for evaluating the effect of reduced splanchnic venous return on intestinal oxygenation 22 . This technique used a probe that was applied gently to the serosal surface of the intestine but did not grip the tissue.…”

“…Intestinal surface oximetry measurement has been identified as a potentially useful method for evaluating the effect of reduced splanchnic venous return on intestinal oxygenation. 22 This technique used a probe that was applied gently to the serosal surface of the intestine but did not grip the tissue.…”

Evaluation of splanchnic oxygen extraction ratio as an index of portal vein pressure in dogs

“…26 Even with these criteria, dogs develop gastrointestinal congestion and ascites following ligation of portosystemic shunts. 13,14 Portal pressure and jejunal surface oxygen tension are significantly correlated in dogs with experimentally induced portal hypertension. 10,25,27 Portal vein pressure also is affected by the hemodynamic status and temperature of patients.…”

“…4 Intraoperative measurement of portal pressure alone can be unreliable because of the effects of anesthesia, administration of inotropes, position of catheters, position of abdominal viscera, phase of respiration, and manipulations of the portal vein. 13 However, limitations associated with measurement of surface oxygen tension include the need to have a relatively long period in which to obtain a steady-state recording, variability among operators, maintenance of consistent contact between sensors and tissues, and peristaltic movements of intestines. 9 Portal hypertension is defined as a persistent increase in portal vascular pressure caused by an increase in portal venous blood flow or by an increase in resistance to portal venous blood flow.…”

“…[13][14][15][16][17] Systemic oxygen extraction ratios have been used to evaluate cardiac output; oxygen extraction ratio can be determined from results of blood gas analyses. However, portal blood flow is difficult to measure in a clinical situation.…”