We will perform this single-center pilot trial to determine if the intraoperative urethral perfusion index is higher in patients assigned to maintaining postinduction baseline urethral perfusion index than in patients assigned to routine care (with blinded urethral perfusion index monitoring). As pre-planned substudies, we will also assess the agreement between a) urethral perfusion index-derived pulse rate and heart rate measured with an electrocardiogram and b) between the urethral perfusion index and the peripheral perfusion index.
at least 45 years old
scheduled for elective major abdominal surgery (involving visceral organs with an expected duration of at least 120 minutes)
indication for an arterial catheter
indication for an urinary catheter
Pregnancy
Planned surgery: nephrectomy, liver or kidney transplantation surgery
Patients who previously had surgery on the urethra or bladder
Patients without clinical indication for continuous blood pressure monitoring with an intraarterial catheter