Rates of major complications and mortality in the first weeks after surgery remain very high: postoperative mortality is still around 2% in central Europe and the United States. Postoperative deaths are a consequence of postoperative complications. Postoperative complications that are most strongly associated with postoperative death include acute kidney injury and acute myocardial injury. To avoid postoperative complications it is thus crucial to identify and address modifiable risk factors for complications. One of these modifiable risk factors may be intraoperative hypotension. Intraoperative hypotension is associated with major postoperative complications including acute kidney injury, acute myocardial injury, and death. It remains unknown which blood pressure value should be targeted in the individual patient during surgery to avoid physiologically important intraoperative hypotension. In current clinical practice, an absolute mean arterial pressure threshold of 65mmHg is used as a lower "one-size-fits-all" intervention threshold. This "population harm threshold" is based on the results of retrospective studies. However, using this population harm threshold for all patients ignores the obvious fact that blood pressure varies considerably among individuals. In contrast to current "one-size-fits-all" perioperative blood pressure management, the investigators propose the concept of personalized perioperative blood pressure management. Specifically, the investigators propose to test the hypothesis that personalized perioperative blood pressure management reduces the incidence of a composite outcome of acute kidney injury, acute myocardial injury, non-fatal cardiac arrest, and death within 7 days after surgery compared to routine blood pressure management in high-risk patients having major abdominal surgery. The investigators will perform preoperative automated blood pressure monitoring for one night to define individual intraoperative blood pressure targets. Automated blood pressure monitoring is the clinical reference method to assess blood pressure profiles. The mission of the trial is to reduce postoperative morbidity and mortality after major surgery. The vision is to achieve this improvement in patient outcome by using the innovative concept of personalized perioperative blood pressure management. This trial is expected to change and improve current clinical practice and will have a direct impact on perioperative blood pressure management guidelines.

Inclusion Criteria:

• Consenting patients ≥45 years scheduled for elective major abdominal surgery under general anesthesia that is expected to last ≥90 minutes AND

• Presence of ≥1 of the following high-risk criteria:

  • exercise tolerance <4 metabolic equivalents as defined by the guidelines of the American College of Cardiology/American Heart Association
  • renal impairment (serum creatinine ≥1.3 mg/dL or estimated glomerular filtration rate <90 mL/min/1.73 m2 within the last 6 months)
  • coronary artery disease (any stage)
  • chronic heart failure (New York Heart Association Functional Classification ≥II)
  • valvular heart disease (moderate or severe)
  • history of stroke
  • peripheral arterial occlusive disease (any stage)
  • chronic obstructive pulmonary disease (any stage) or pulmonary fibrosis (any stage)
  • diabetes mellitus requiring oral hypoglycemic agent or insulin
  • immunodeficiency due to a disease (e.g., HIV, leukemia, multiple myeloma, solid organ cancer) or therapy (e.g., immunosuppressants, chemotherapy, radiation, steroids [above Cushing threshold])
  • liver cirrhosis (any Child-Pugh class)
  • body mass index ≥30 kg/m2
  • current smoking or 15 pack-year history of smoking
  • age ≥65 years
  • expected anesthesia duration >180 minutes
  • B-type natriuretic peptide (BNP) >80 ng/L or N-terminal B-type natriuretic peptide (NT-proBNP) >200 ng/L within the last 6 months

Exclusion Criteria:

• emergency surgery
• surgery: nephrectomy, liver or kidney transplantation
• status post transplantation of kidney, liver, heart, or lung
• sepsis (according to current Sepsis-3 definition)
• American Society of Anesthesiologists physical status classification V or VI
• pregnancy
• patients on renal replacement therapy
• impossibility of preoperative automated blood pressure monitoring

In patients in the routine management group, the treating anesthesiologists will be blinded to data of preoperative automated blood pressure monitoring to avoid performance bias. Participants are blinded to group allocation.