Post-operative morbidity and mortality is related to many factors related to the patient's condition, the intra-operative period and the optimisation of intra-operative haemodynamic and respiratory parameters. Many studies have looked at the determinants and factors that increase postoperative complications. However, these have been randomised studies looking at one parameter in particular.

This analysis would be the first to investigate the determinants of postoperative complications in a large population of patients undergoing major non-cardiac surgery. This is a post-hoc analysis of patients included in the OPHIQUE study, whose main objective was to evaluate intraoperative haemodynamic management guided by a marker of tissue hypoperfusion (the respiratory quotient).

Inclusion Criteria:

• Abdominal, orthopaedic or vascular surgery under general anaesthesia and with an estimated duration of surgery > 2 hours
• Adult patients (age ≥ 18 years)
• ASA score ≥ II
• Patient with at least two of the following comorbidities: age > 50 years, high blood pressure (HTA), heart failure, ECG abnormality, smoking, stroke, transient ischemic attack (TIA), peripheral arterial disease (PAD), insulin-dependent or non-insulin-dependent diabetes mellitus (NIDDM), ascites, chronic renal failure (CRF)
• Signature of the consent form
• Affiliation to a social security scheme

Exclusion Criteria:

• Severe untreated or unbalanced hypertension
• Preoperative renal failure on dialysis
• Acute heart failure
• Acute coronary insufficiency
• Vascular surgery with renal plasty
• Cardiac surgery
• Permanent laparoscopy
• Chronic respiratory failure with home oxygen therapy
• Acute respiratory distress syndrome with FiO2>60%.
• Preoperative shock
• Surgery under spinal anaesthesia and epidural only
• Refusal to participate by the patient
• Pregnant, parturient or breastfeeding women
• Patients under guardianship or curators, under court protection or deprived of public rights
• The patient already included in another therapeutic trial with an experimental molecule
• Emergency surgery
• Patients who do not want their personal data to be used in the framework of the research

• Abdominal, orthopaedic or vascular surgery under general anaesthesia and with an estimated duration of surgery > 2 hours
• Adult patients (age ≥ 18 years)
• ASA score ≥ II
• Patient with at least two of the following comorbidities: age > 50 years, high blood pressure (HTA), heart failure, ECG abnormality, smoking, stroke, transient ischemic attack (TIA), peripheral arterial disease (PAD), insulin-dependent or non-insulin-dependent diabetes mellitus (NIDDM), ascites, chronic renal failure (CRF)