Effect of acute ischemic preconditioning on blood-flow response in the epigastric pedicled rat flap

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.