Intraoperative hypotension is common in patients having non-cardiac surgery with general anesthesia and is associated with organ injury and death. The timely treatment of intraoperative hypotension is thus important to avoid postoperative complications. About one third of intraoperative hypotension occurs during anesthetic induction - i.e., between the start of anesthetic induction and surgical incision. Hypotension during anesthetic induction is associated with postoperative acute kidney injury.

Unmodifiable risk factors for hypotension during anesthetic induction include age, male sex, and a high American Society of Anesthesiologists physical status class. However, hypotension during anesthetic induction is mainly driven by modifiable factors - specifically, anesthetic drugs that cause vasodilation.

In most German hospitals, norepinephrine is the first-line vasopressor to treat hypotension during anesthetic induction. Norepinephrine is usually given as repeated manual boluses of 5, 10, or 20 μg. The continuous administration of norepinephrine via a perfusion pump is usually started only later. It remains unknown whether giving norepinephrine continuously - compared to giving it as repeated manual boluses - reduces hypotension during anesthetic induction.

We thus propose to investigate whether giving norepinephrine continuously - compared to giving it as repeated manual boluses - reduces hypotension during anesthetic induction in non-cardiac surgery patients.

Inclusion Criteria:

• non-cardiac surgery
• >45 years of age
• American Society of Anesthesiologists physical status classification II, III, and IV.

Exclusion Criteria:

• Planned intraarterial blood pressure monitoring during anesthetic induction with an arterial catheter
• Emergency surgery
• Transplant surgery
• History of organ transplant
• Pregnancy
• Heart rhythms other than sinus rhythm
• Impossible Finger-cuff blood pressure monitoring
• Rapid sequence induction