Detection of free radicals in reperfused dog skin flaps using electron paramagnetic resonance spectroscopy: a pilot study.

This is a preliminary investigation of the usefulness of spin-trapping electron paramagnetic resonance (EPR) in detecting oxygen-derived free radicals after reperfusion of ischemic skin flaps. Fourteen island skin flaps approximately 12 cm long by 6 cm wide based on the caudal superficial epigastric vessels were isolated in seven dogs. Seven of the paired skin flaps were subjected to 4 hours of arterial and venous occlusion. The opposite skin flap on each dog served as a perfused control. Spin trapping-EPR was able to detect radical adducts in five of the seven reperfused skin flaps. Hyperfine splitting constants of the radical adducts from the blood of three of the flaps confirmed biologically derived free radical production. Contaminating EPR signals from free radicals created in the manufacture of plastics probably masked any biologically derived radical adducts in the remaining flaps. The authors conclude that EPR-spin trapping may be a valuable tool in the study of the importance of oxygen-derived free radicals in the failure of skin flaps subjected to transient ischemia.