Measurement Agreement Between IBP and NIBP During Induction of Anesthesia in High Risk Patients

The AGREE-BP study aims to evaluate how closely blood pressure measurements taken with an automated upper-arm cuff agree with measurements taken through a small plastic tube placed in an artery, called an arterial catheter, during the start of general anesthesia. Blood pressure can change rapidly when patients receive medication to induce general anesthesia. These changes may be particularly pronounced in patients with heart or blood vessel disease or high blood pressure. An upper-arm cuff measures blood pressure at intervals, whereas an arterial catheter measures it continuously with each heartbeat. Although cuff measurements are widely used, their agreement with arterial catheter measurements during this period of rapid change is not fully evaluated and validated. This observational study will include 120 patients undergoing surgery under general anesthesia at University Hospital Graz, Austria. Participants will have conditions that increase their risk of blood pressure changes and will already require an arterial catheter before anesthesia for medical reasons. During the first five minutes after administration of the medication used to induce anesthesia, researchers will record blood pressure using both methods. The cuff will be placed on the arm opposite the arterial catheter and will take measurements at least once per minute, or more frequently if the monitor allows. Anesthesia and treatment decisions will remain the responsibility of the treating clinician. Participation does not require additional follow-up visits. The main aim is to assess agreement in mean arterial pressure, which is the average pressure in the arteries over a heartbeat. Researchers will also compare systolic pressure, the pressure when the heart contracts, and diastolic pressure, the pressure when the heart relaxes. They will examine whether patient characteristics or treatments are associated with differences between the two measurement methods and will separately assess agreement during particularly large, rapid blood pressure changes. The findings may help clinicians understand when cuff measurements differ meaningfully from arterial catheter measurements and inform future decisions about blood pressure monitoring during the start of anesthesia.