ASSESSMENT OF ISCHEMIA AND REPERFUSION INJURY

Direct videomicroscopy of the rat cremaster muscle microcirculation su pplemented by animal models of replantation, vascular crushing, and mu scle function after injury and recovery were used to investigate the o ccurrence of reperfusion failure, It is evident that failure of blood reflow may be induced by multiple factors that can be grouped into cat egories of ischemia, intimal damage, and systemic or local responses, which are referred to as the no reflow triad, The components comprisin g the 3 sides of the no reflow triad can interact with one another in an intricate manner, and any single factor or combination of factors i s capable of triggering the events leading to reperfusion failure, The pronounced regional nature of reperfusion injury and the direct relat ionship between the severity of the observed vascular alterations and increasing duration of ischemia have been documented, The dynamic chan ges and histopathology of the microcirculation included constriction o f the arteries, swelling of endothelial and leukocytes, and erythrocyt e rouleaux formation during ischemia, As ischemia duration was lengthe ned, the degree of these changes increased correspondingly, The change s on reperfusion were disruption of blood flow patterns, vortex format ion, regional stasis, adhesion and migration of leukocytes, focal hemo rrhage, edema, vasospasm, and platelet aggregation. The deleterious ef fects of systemic acidosis, interstitial hemorrhage, denervation, and prolonged venous occlusion were subsequently documented, The applicati on of information gained from this series of laboratory experiments ha s resulted in continued improvement in the success rate in clinical mi crovascular surgery.