Ischemic time and free flap success.

Ischemic time (the time between the interruption and reestablishment of blood supply) was reviewed for 700 free flaps used for breast or head and neck reconstruction. Flaps that failed had a mean ischemic time of 111.64 minutes, while flaps that survived had a mean ischemic time of 91.25 minutes. The difference was not statistically significant (p = 0.189). The patients were then divided into two groups: those with flap ischemic times of 100 minutes or longer and those with flap ischemic times less than 100 minutes. We found that flap survival was similar in the two groups. Flap survival was also similar when 75 minutes and 120 minutes were used to segregate the longer and shorter ischemic time groups. When 180 minutes was used to segregate the groups, there was a slight trend toward more flap loss in the group with longer ischemic time, but the difference was not significant. We conclude that ischemic time is irrelevant to flap survival, provided that ischemia is not prolonged past 3 hours or to the point where the no-reflow phenomenon occurs.