Background: Several in vivo techniques that assess mucosal perfusion by intraluminal probes have recently been developed and validated, including laser Doppler flowmetry, reflectance spectrophotometry, and tonometry.
Methods: With these techniques, a canine model where the entire vascular supply to the jejunoileum was isolated as the superior mesenteric artery and vein was used to examine the relationship between enteric mucosal blood perfusion and adjusted decrements in arterial flow under fasting and postprandial conditions.
Results: Mucosal perfusion measured by laser Doppler flowmetry and reflectance spectrophotometry correlated linearly with decrements in superior mesenteric artery flow (r2 = 0.96 and 0.98, respectively); estimation of mucosal pH by tonometry decreased only after a critical level of arterial inflow was reached (less than 50% of baseline flow). Mucosal perfusion increased after the meal throughout the jejunoileum with unrestricted superior mesenteric artery flow. However, with restricted superior mesenteric artery flow, nutrient delivery to the jejunum was accompanied by increased mucosal perfusion at that level but by decreased perfusion in the distal ileum not exposed to nutrients. This latter response represents a distal to proximal redistribution of blood, i.e., an intramesenteric steal phenomenon.
Conclusions: In vivo measurements of mucosal perfusion reflected changes in large mesenteric vessel blood flow. These intraluminal techniques discriminated between a normal and an impaired mesenteric circulation in an acute model and may have clinical application.