Objective—To determine whether small intestinal
ischemia and reperfusion affects intestinal intramucosal
pH (pHi), arterial and portal venous blood gas
values, and intestinal blood flow (IBF) and to investigate
relationships between regional intestinal tissue
oxygenation and systemic variables in dogs.
Animals—15 healthy adult Beagles.
Procedure—Occlusion of superior mesenteric artery
(SMA) for 0, 30, or 60 minutes, followed by reperfusion
for 180 minutes, was performed; IBF, pHi, arterial and
portal venous blood gas values, arterial pressure, and
heart rate were measured at various time points; and
intestinal mucosal injury was histologically graded.
Results—Occlusion of the SMA induced significant
decreases in pHi and IBF. After the release of the
occlusion, IBF returned rapidly to baseline values, but
improvement in pHi was slow. Arterial and portal
venous blood gas analyses were less sensitive than
tonometric measurements of pHi, and there was no
correlation between results of blood gas analyses and
tonometric measurements. Histologic score for intestinal
mucosal injury increased significantly, depending
on duration of ischemia, and there was a correlation
between tonometric results and the histologic score.
Conclusion and Clinical Relevance—Results suggest
that it is difficult to accurately evaluate local oxygenation
disorders by monitoring at the systemic
level, whereas clinically pHi is the only reliable indicator
of inadequate regional intestinal tissue oxygenation
in dogs. (Am J Vet Res 2002;63:804–810)