Effect of Acute Ischemic Preconditioning on Blood-Flow Response in the Epigastric Pedicled Rat Flap

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

REFERENCES

• 1 Al Qattan M M, Boyd B. Complications in head and neck microsurgery.  Microsurgery . 1993;  14 187
• 2 Khouri R K, Cooley B C, Kunselman A R. A prospective study of microvascular free-flap surgery and outcome.  Plast Reconstr Surg . 1998;  102 711
• 3 Mounsey R A, Pang C Y, Forrest C. Preconditioning: a new technique for improved muscle flap survival.  Otolaryngol Head and Neck Surg . 1992;  107 549
• 4 Pang C Y. Ischemia-induced reperfusion injury in muscle flaps: pathogenesis and major source of free radicals.  J Reconstr Microsurg . 1990;  6 77
• 5 Restifo R J, Thomson J G. The preconditioned TRAM flap: preliminary clinical experience.  Ann Plast Surg . 1998;  41 343
• 6 Mounsey R A, Pang C Y, Boyd J B. Augmentation of skeletal muscle survival in the latissimus dorsi porcine model using acute ischemic preconditioning.  J Otolaryngol . 1992;  21 315
• 7 Wang W Z, Anderson G, Maldonado C. Attenuation of vasospasm and capillary no-reflow by ischemic preconditioning in skeletal muscle.  Microsurgery . 1996;  17 324
• 8 Zahir K S, Syed S A, Zink J R. Ischemic preconditioning improves the survival of skin and myocutaneous flaps in a rat model.  Plast Reconst Surg . 1998;  102 140
• 9 Carroll C MA, Carroll S M, Overgoor M LE. Acute ischemic preconditioning of skeletal muscle prior to flap elevation augments muscle flap survival.  Plast Reconstr Surg . 1997;  100 58
• 10 Petry J J, Wortham K A. The anatomy of the epigastric flap in the experimental rat.  Plast Reconstr Surg . 1984;  74 410
• 11 Blondeel P N, Beyens G, Verhaeghe R. Doppler flowmetry in the planning of perforator flaps.  Br J Plast Surg . 1998;  51 202
• 12 Fischer J C, Parker P M, Shaw W W. Comparison of two laser Doppler flowmeters for the monitoring of dermal blood flow.  Microsurgery . 1983;  4 164
• 13 Place M J, Witt P, Hendricks D. Cutaneous blood-flow patterns in free flaps determined by laser Doppler flowmetry.  J Reconstr Microsurg . 1996;  12 355
• 14 Yoshino K, Nara S, Endo M. Intraoral free flap monitoring with a laser Doppler flowmeter.  Microsurgery . 1996;  17 337
• 15 Murry C E, Jennings R B, Reimer K A. Preconditioning with ischemia: a delay of lethal cell injury in ischemic myocardium.  Circulation . 1986;  74 1124
• 16 Pang C Y, Yang R Z, Zhong A. Acute ischemic preconditioning protects against skeletal muscle infarction in the pig.  Cardiovasc Res . 1995;  29 782
• 17 Pang C Y, Forrest C R, Mounsey R. Pharmacologic intervention in ischemia-induced reperfusion injury in the skeletal muscle.  Microsurgery . 1993;  14 176
• 18 Cohen M V, Downey J M. Myocardial preconditioning promises to be a novel approach to the treatment of ischemic heart disease.  Ann Rev Medicine . 1996;  47 21
• 19 Wang W Z, Anderson G, Fleming J T. Local infusion of nitroprusside but not acetylcholine attenuates vasospasm associated with ischemia and reperfusion in vascular isolated cremaster muscle.  Microcirculation . 1995;  2 66
• 20 Standen N B, Quayle J M, Davies N W. Hyperpolarizing vasodilators activate ATP sensitive K⁺ channels in arterial smooth muscle.  Science . 1989;  145 177
• 21 Johnson P C. Autoregulation of blood flow.  Circ Res . 1986;  59 483
• 22 Ren T, Avinash G B, Nuttall A L. Dynamic response of cochlear blood flow to occlusion of the anterior inferior cerebellar artery in guinea pigs.  J Appl Physiol . 1994;  76 212