The PROTECT Trial: PROpofol Titration to Enhance haemodynamiC sTability

Inclusion Criteria: * Adults ≥ 55 years old * Patients undergoing any of the following planned surgery under general anaesthesia with intubation: Ear, nose and throat, gynaecological, maxillofacial, orthopedic, plastic and reconstructive, spine, urologic, vascular (varicose vein surgery, femoral endarterectomy, peripheral bypass surgery) and visceral surgery * Standard procedure for anaesthesia with propofol Target-Controlled Infusion (TCI) using the Schnider model and remifentanil TCI using the Minto model * American Society of Anesthesiologists Physical Status Classification system (ASA PS) I-IV * Body mass index (BMI) ≥18.5 or \<35 kg/m2 * Signed written informed consent Exclusion Criteria: * Special forms of anaesthesia induction, specifically awake tracheal intubation and rapid sequence induction * Combined anaesthesia procedures (general and regional anaesthesia combined) * Special forms of general anaesthesia (opioid-free anaesthesia or any opioid-sparring modifications with lidocaine, magnesium, ketamine, clonidine or dexmedetomidine) * Surgery in the prone position within the first 30 minutes * Patients with known difficult airway * Daily consumption of alcohol (\> one unit/day) or \> seven units/week * Any regular recreational drug abuse * Chronic use of benzodiazepines or opioids * Allergy to propofol * Patients with known brain pathologies, specifically seizure disorders, stroke within the past 9 months or dementia * History of awareness * Inability to follow procedures or insufficient knowledge in German