Laser Doppler flowmetry in experimental mesenteric vascular occlusion.

The performance of the laser Doppler-signal (measuring blood flow) and the direct current-signal (measuring the amount of backscattered light) were studied in isolated segments of feline small intestine during arterial or venous occlusion. Following total arterial or venous occlusion, the LD-signal rapidly fell to 16% and 29% of control values, respectively. The DC-signal decreased significantly (to 78% of control, p less than 0.001) in response to venous occlusion but did not change significantly following arterial occlusion. After total venous occlusion, the amount of backscattered light was sometimes insufficient to allow flow measurement, probably due to high light absorption in the congested tissue. After ligation of the vascular stalk, the LD-signal soon decreased to 10-15% of control but did not reach the baseline until 4-6 hours. It is suggested that this residual LD-signal is caused by activity in the muscularis layer in the early phase of intestinal infarction.