Continuous versus intermittent noninvasive blood pressure measurement in patients undergoing surgery in the beach-chair position

This study is comparing two ways to monitor blood pressure during surgery performed in the "beach-chair" position (sitting up at an angle, such as during shoulder or thyroid surgery). In this position, blood pressure in the brain can drop dangerously, potentially causing brain injury. The standard approach measures blood pressure every few minutes using an inflatable cuff; this study tests a newer device that measures blood pressure continuously without any needles or tubes. Researchers will compare how often blood pressure goes too low and how patients are mentally affected after surgery. You may be eligible if: - You are 18 years or older - You are having shoulder surgery, shoulder arthroscopy, or thyroid surgery in the beach-chair position - You will have general anaesthesia - You have given written informed consent You may NOT be eligible if: - You have an obvious blood flow problem in the arm being monitored - You have a vascular implant or a neurological or neuromuscular disease in the arm being monitored - You have peripheral oedema (limb swelling) Talk to your doctor about whether this trial might be right for you.