The effect of hemoglobin and hematocrit levels on free flap survival.

There has been experimental information suggesting that iatrogenic anemia may improve the survival of pedicled free flaps. This has been attributed to a decrease in blood viscosity secondary to hemodilution. The hemoglobin (Hb) and hematocrit (Hct) levels of 14 successful and 6 failed free flaps at the time of operation, during hospitalization, and at discharge are reviewed. There was no difference in Hb or Hct levels between successful and failed flaps. Reconstruction of traumatic defects showed an increased risk of failure. If flaps survived longer than 10-14 days, they were unlikely to fail subsequently. In conclusion, Hb and Hct levels in clinically acceptable ranges have no effect on free flap survival.