Effect of Goal-directed Fluid Therapy Using Stroke Volume Variation in Patients Undergoing Free Flap Reconstruction After Head and Neck Cancer Resection

In Standard fluid therapy group, the administration of fluid will be guided to maintain mean blood pressure more than 65 mmHg, urine output more than 0.5 ml/kg/hr, and central venous pressure less than 14 mmHg.

In Goal directed fluid therapy group, the administration of fluid will be guided by stroke volume variation. The anesthesiologist will infuse volulyte (Fresenius Kabi, Bad Homburg, Germany) 200 ml if stroke volume variation is over 12%. If cardiac index is below 2.5 l/min/m2 and stroke volume variation is below 12%, start dobutamine.