The Hypotension Prediction Index in Free Flap Transplant in Head and Neck Surgery.

This study is evaluating a monitoring tool called the Hypotension Prediction Index (HPI) — a technology that uses blood pressure waveforms to predict drops in blood pressure before they happen — in patients undergoing complex head and neck reconstruction surgery (called free flap surgery). The goal is to improve blood pressure management during surgery and protect the delicate tissue transplant. **You may be eligible if...** - You are scheduled for head and neck free flap (tissue reconstruction) surgery - You are 18 years or older - You are able to provide written consent **You may NOT be eligible if...** - You are under 18 years old - You are pregnant - You do not have health insurance - You have a history of congenital heart disease, severe heart valve narrowing, heart failure with very low pumping function, or persistent irregular heart rhythm (atrial fibrillation) Talk to your doctor to see if this trial is right for you.