INTRALUMINAL MEASUREMENT OF ENTERIC MUCOSAL PERFUSION - RELATIONSHIP TO SUPERIOR MESENTERIC-ARTERY FLOW DURING BASAL AND POSTPRANDIAL STATES IN THE DOG

Background. Several in vivo techniques that assess mucosal perfusion b y intraluminal probes have recently been developed and validated, incl uding laser Doppler flowmetry, reflectance Methods. With these techniq ues, a canine model where the entire vascular supply to the jejunoileu m 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 co nditions. Results. Mucosal perfusion measured by laser Doppler flowmet ry and reflectance spectrophotometry correlated linearly with decremen ts in superior mesenteric artery flow (r(2) = 0.96 and 0.98, respectiv ely); estimation of mucosal pH by tonometry decreased only after a cri tical level of arterial inflow was reached (less than 50% of baseline flow) . Mucosal perfusion increased after the meal throughout the jeju noileum with unrestricted superior mesenteric artery pow. However, wit h 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 nutrient s. 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 mese nteric vessel blood flow. These intraluminal techniques discriminated between a normal and an impaired mesenteric circulation in an acute mo del and may have clinical application.