ABSTRACT
Research in the field of microvascular surgery has shown that ischemic preconditioning
(repeated brief episodes of feeding artery occlusions followed by reperfusion) improves
flap survival. The authors used a custom-designed clamping method and laser Doppler
flowmetry to investigate changes in blood flow (BF) responses, either with acute ischemic
preconditioning or without it. The animal model used was the partially elevated epigastric
flap of adult Sprague-Dawley rats. In the preconditioned group (n=12), the flaps underwent
preconditioning with three cycles of 10-min of feeding artery clamping, followed by
10 min of reperfusion, for a total preconditioning period of 1 hr. In the control
group (n=12), the flaps were perfused without clamping for 1 hr. All the flaps underwent
occlusion of the feeding artery for 15, 30, 60, 120 and 180 sec to observe the changes
in the BF responses, 60 min and 150 min after flap elevation. To compare the responses
between preconditoned and control groups the BF responses were analyzed during the
overshoot period (i.e., BF being above the baseline after different feeding artery
occlusion periods). Statistical analysis of the responses showed that the magnitude
of increase in BF after clamp release (p<0.001), the duration of overshoot (p=0.014), and the amplitude of overshoot after clamp release (p=0.002) were statistically significantly greater in the preconditioned group than
in the control group. The results suggest that vessels and their responses to change
in perfusion pressure are involved in the multifactorial process of the ischemia-protective
effect caused by acute ischemic preconditioning. As far as is known, this is the first
report showing changes in flap vascular responses after acute ischemic preconditioning.
KEYWORD
Hemodynamics - blood flow - laser Doppler flowmetry - free flap - microsurgery - acute
ischemic preconditioning
