Postoperative Hemorrhage

The goal of this clinical trial is to learn whether the Hemorai Vysio wearable device can be used safely and feasibly to track relative changes over time in tissue oxygen, hemoglobin-related signals, blood flow, and oxygen use during and after inpatient surgery. The device does not provide absolute clinical measurements. The investigators will also explore whether changes recorded by the device occur around signs or treatments related to blood loss. The main questions are: * Can the device collect usable information during and after surgery without interfering with routine care? * What device-related problems, such as skin irritation or discomfort, occur? * Do changes in the device measurements occur around changes in blood pressure, laboratory results, fluid administration, or blood transfusion? * How comfortable and practical is the device for participants and bedside nurses? Participants undergoing surgery will wear the device on the upper arm or chest. Trained study staff will apply the device before surgery. The device will remain in place for up to 48 hours after surgery, or until discharge or earlier removal. Participants will continue to receive usual hospital monitoring and care. Bedside nurses may also join the study and complete a short voluntary survey. Nurses may check the device position and adjust the strap for comfort. Nurses will not interpret the device measurements or use the measurements to make treatment decisions. Hemorai Vysio is an investigational device. The device measurements will be analyzed for research and will not be used to guide participants' medical care. Participants are not expected to receive a direct medical benefit from taking part.