Hypotension is a frequent complication after induction of general anaesthesia leading to end-organ injury, for which elderly and multimorbid patients are particularly susceptible. The extent of hypotension depends, among other factors, on the dose and rate of propofol administration. Target-controlled infusion systems are widely used to administer short-acting anaesthetics such as propofol and remifentanil. Commonly, induction is started with a fixed effect-site concentration. Titration, an alternative method of induction using an incremental augmentation of propofol, leads to a reduced induction dose and rate of propofol. We hypothesise that the titration method improves haemodynamic stability compared with conventional induction.

This multicentre, expertise-based randomised controlled trial takes place at four Swiss hospitals. Patients ≥55 years of age undergoing non-cardiac surgery under general anaesthesia using propofol target-controlled infusion are randomised to either a conventional or a titrated anaesthesia induction method. Patients, statisticians and, if resources allow, outcome assessors will be blinded. The primary endpoint is the mean arterial pressure under the individual baseline mean arterial pressure (area under threshold) during the first 30 min after start of induction. Secondary endpoints include the maximum deviation from baseline mean arterial pressure, haemodynamic rescue methods, propofol consumption and neurocognitive recovery after regaining consciousness.

A total of 320 patients are required to have an 80% chance of observing superiority of titration for the area under the threshold as significant at the 5% level, assuming a true difference of 100 mm Hg*min. The area under threshold and the maximum deviation will be compared between arms using mixed linear regression models.

Ethical approval has been obtained from all responsible ethics committees (BASEC2025-01007). The results will be presented at international meetings and published in peer-reviewed journals and may contribute to a change in clinical practice for anaesthesia induction using target-controlled infusion systems with propofol.

clinicaltrials.gov (NCT06980688) and www.humanforschung-schweiz.ch (HumRes67022).