Effect of anemia on survival of myocutaneous flaps in the pig

The decision to transfuse patients after major head and neck reconstructive surgery has been influenced by the dictum that a hematocrit level of 30% or more is necessary for the survival of surgical flaps. Pedicled myocutaneous flaps are among the most frequently used methods of reconstruction after major head and neck oncologic surgery. No studies have addressed the survival of myocutaneous pedicled flaps in anemic animals. In this study survival of latissimus dorsi myocutaneous flaps in pigs was evaluated in anemic and control groups. A total of 26 pigs were randomly divided into two groups. The pigs in the anemic group were exsanguinated to normovolemic anemia (average hematocrit, 19%), followed by elevation of a latissimus dorsi myocutaneous flap. In the control group the same operation was performed without exsanguination. All other variables were kept constant. The flap survival was judged on postoperative days 3, 7, and 14 by two evaluators. Ten pigs from each group were found to have 100% flap survival on post-operative day 14. There was no significant difference in mean flap survival rates between two groups for postoperative days 3, 7, and 14. It is concluded that normovolemic anemia does not adversely affect the survival of the myocutaneous flaps. This finding may save unnecessary transfusions in postoperative patients.