ULTRAVIOLET EXCITATION FLUORESCENCE SPECTROSCOPY - A NONINVASIVE METHOD FOR THE MEASUREMENT OF REDOX CHANGES IN ISCHEMIC MYOCUTANEOUS FLAPS

In this report, we discuss application of the noninvasive technology o f ultraviolet fluorescence spectroscopy to the metabolic analysis of n ormal and compromised myocutaneous flaps. Acute changes in tissue redo x states during ischemia and reperfusion were determined analysis of c hanges in the fluorescence spectrum of reduced nicotinomide adenine di nucleotide (NADH). Analysis of the system for NADH fluorescence showed good correlation between excitation spectra recorded at 450 nm from p ure beta-NADH and those recorded from porcine rectus abdominis myocuta neous flaps. Sequential measurements of surface fluorescence were obta ined from six flaps subjected to 6 hours of warm arterial ischemia and 4 hours of reperfusion. Results were compared with spectra obtained f rom six contralateral nonischemic control flaps. A significant mean in crease in NADH fluorescence (49 percent; p < 0.05) was demonstrated wi thin 30 minutes of vascular occlusion. Fluorescence intensity continue d to increase throughout the ischemic period, reaching 320.5 percent o f baseline values at 6 hours. Reperfusion resulted in the prompt retur n of fluorescence intensity to baseline levels. These results show tha t fluorescence spectroscopy of endogenous NADH is a sensitive and reli able indicator of vascular occlusion in experimental myocutaneous flap s.