Effective dose of dobutamine in augmenting free flap blood flow during reconstructive surgery of the lower extremity

Success of surgical free flap transfer depends on achieving and maintaining adequate perfusion across the microvascular anastomosis. The purpose of this prospective study was to determine the optimal infusion rate of dobutamine to augment duplex ultrasound measured blood flow to the tissue flap during surgery.Twenty-one patients undergoing general anesthesia for lower limb reconstructive surgery were recruited. The optimal dobutamine dose was evaluated using the modified Dixon's up-and-down method, starting at 6 μg·kg·min, and then titrated in increments of 1 μg·kg·min.The optimal dose of dobutamine for improving blood flow to the tissue flap was 3.50 ± 0.57 μg·kg·min in 50% of patients. The 95% effective dose of dobutamine calculated by probit analysis was 4.46 μg·kg·min (95% confidence interval: 3.99-7.00 μg·kg·min).The results of our study suggest that a dobutamine infusion rate less than 5 μg·kg·minprovides significant improvement of blood flow to the tissue flap, while minimizing cardiovascular side effects.