Remote ischemic preconditioning (RIPC) has been revealed organ-protective effect in many previous clinical settings including coronary intervention or cardiovascular surgery. However its protective role during free flap reconstructive surgery in head and neck cancer patients has not yet been elucidated. The purpose of the current study is to evaluate the effect of RIPC on tissue oxygen saturation and skin temperature of the flap, as well as its organ-protective effect using Langendorff isolated heart ischemia-reperfusion model.

Patients undergoing free flap reconstructive surgery for head and neck cancer will be randomized to either remote ischemic preconditioning (RIPC) group or control group. On the day of surgery, after induction of anesthesia, RIPC, consisting of 4 cycles of 5-min ischemia (using pneumatic cuff pressure of 200 mmHg) followed by 5-min reperfusion at upper arm, or sham-RIPC (pressure < 10 mmHg) will be induced in the RIPC or control group, respectively. Before completion of surgery, RIPC or sham-RIPC will be repeated. Tissue oxygen saturation and skin temperature of the flap will be recorded until postoperative day 1.

As a sub-study, blood samples will be obtained before and after RIPC/sham-RIPC. From them, plasma dialysate will be prepared to use for Langendorff isolated heart model. Myocardial infarct size of Langendorff rat heart will be compared between the groups to evaluate organ protective effect of RIPC during free flap reconstuctive surgery.

Inclusion Criteria:

• patients undergoing free flap reconstructive surgery

Exclusion Criteria:

• BMI < 18, > 35 kg/m^2
• AV fistula at arm, any reason to protect arm
• vascular abnormality or discomfort at arm
• peripheral vascular disease, peripheral neuropathy, or coagulopathy
• uncontrolled diabetes mellitus
• preoperative use of beta-blocker
• history of radiation therapy
• refuse to enrol