2.5 Versus 5 Minutes Trial

Oscillometric Blood Pressure Measurement At 2.5- Vs. 5-minute Intervals and Hypotension in Patients Having Non-cardiac Surgery: a Randomized Trial

This is a randomized trial investigating the effect of oscillometric blood pressure monitoring at 2.5-minute intervals - compared to 5-minute intervals - on intraoperative hypotension. Specifically, the investigators will test the primary hypothesis that oscillometric blood pressure monitoring at 2.5-minute intervals - compared to 5-minute intervals - reduces the time-weighted average mean arterial pressure below 65 mmHg in patients having non-cardiac surgery.

Inclusion Criteria:

• ≥45 years
• scheduled for elective non-cardiac surgery under general anesthesia
• planned oscillometric blood pressure monitoring with an upper-arm cuff
• American Society of Anesthesiologists physical status class II or higher

Exclusion Criteria:

• emergency surgery
• arm or shoulder surgery
• pregnancy
• preoperative blood pressure differences between the right and left arm of more than 20 mmHg
• intraoperative invasive blood pressure monitoring
• previous preoperative peripheral nerve injury (such as diabetic neuropathy, carpal tunnel syndrome, or cervical radiculopathy)
• contraindication for continuous finger-cuff blood pressure monitoring (e.g., Raynaud's disease, arterial-venous shunts, or cardiac assist devices)