ABSTRACT
Although the effectiveness of cooling in extending tolerable ischemia time is well-established
experimentally, most free-flap surgeons are still concerned about this problem and
try to limit the ischemic period to less than 1 hr. Clinically, contact-surface cooling
has been used empirically to prolong the limits of ischemia time; however, its applications
are unproven. It also remains unknown whether contact-surface cooling has detrimental
effects on flap tissue, such as vessel spasm leading to thrombosis. The purpose of
this study was to determine, in a clinical setting, if skin, muscle, and bone free
flaps of considerable size could tolerate prolonged cold ischemia without adverse
effects. Flap 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 rate 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). The 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 statistically significant
correlations existed between duration of ischemia time or duration of contact-surface
cooling and the incidence of thrombosis, flap complication, or flap failure. Among
the conclusions were that, within a 4-hr period of cold ischemia, the application
of the surface-cooling technique is not detrimental to free flap surgery; thus, concern
for ischemia, and especially the “no reflow” phenomenon, generally should not interfere
with efficient and orderly free-flap surgery.
