BIODISTRIBUTION OF INDOCYANINE GREEN IN A PORCINE BORN MODEL - LIGHT AND FLUORESCENCE MICROSCOPY

Background: Infrared-excited fluorescence of intravenously administere d indocyanine green (ICG) is being used as a method of early determina tion of burn depth. Methods: Fluorescence microscopy and tissue fluore scence were recorded in a porcine burn model and correlated to burn se verity and age. Results: Recently placed superficial burns show signif icant fluorescence compared with adjacent normal tissue as a result of a strong inflammatory reaction in the superficial dermis with minimal vascular occlusion. The magnitude of the inflammatory reaction decrea ses with time. For deeper burns, vascular occlusion prevents transport of ICG into the burn and the intensity of ICG fluorescence in burn es char is negligible. Conclusion: The intensity of ICG fluorescence meas ured at the surface of the wound for burns of similar age was shown to decrease exponentially with the depth of the burn. The enhanced fluor escence of partial-thickness burns is attributable to increased permea bility, and the decreased signal associated with deeper injuries is at tributable to vascular occlusion. These results suggest that it is pos sible to differentiate burns that will heal spontaneously with minimal granulation from those that will not by measuring the intensity of IC G fluorescence.