SAFE ISCHEMIA TIME IN FREE-FLAP SURGERY - A CLINICAL-STUDY OF CONTACT-SURFACE COOLING

Although the effectiveness of cooling in extending tolerable ischemia time is well-established experimentally, most free-flap surgeons are s till concerned about this problem and try to limit the ischemic period to less than hr. Clinically contact-surface cooling has been used emp irically to prolong the limits of ischemia time; however, its applicat ions are unproven, it also remains unknown whether contact-surface coo ling has detrimental effects on flap tissue, such as vessel spasm lead ing to thrombosis. The purpose of this study was to determine, in a cl inical setting, if skin, muscle, and bone free flaps of considerable s ize could tolerate prolonged cold ischemia without adverse effects. Fl ap size, cold ischemia time, and surgical outcomes were studied in 189 consecutive free flaps. Microvascular thrombosis occurred in 5/378 (1 .3 percent) of anastomoses. The overall flap complication/flap loss ra te was 7/189 (3.7 percent). Mean ischemia time for all flaps was 2 hr and 6 min (range: 30 min to 5 hr, with one case at 6 hr and 8 min). Th e mean ischemia time for cases with flap complications was 2 hr 20 min , while ischemia time for cases with thrombosis averaged 2 hr 13 min. The one flap loss had an ischemia time of 1 hr 35 min. No statisticall y significant correlations existed between duration of ischemia time o r duration of contact-surface cooling and the incidence of thrombosis, nap complication, or flap failure. Among the conclusions were that, w ithin a 4-hr period of cold ischemia, the application of the surface-c ooling technique is not detrimental to free flap surgery; thus, concer n for ischemia, and especially the ''no reflow'' phenomenon, generally should not interfere with efficient and orderly free-flap surgery.