Objective: To determine the optimal propofol target concentration between 0.9-1.1 and 1.3 mg l(-1), for conscious sedation and amnesia using Diprifusor in ASA III patients over 60 years.
Study design: Prospective study.
Patients and methods: In ASA III patients over 60 years presented for elective vascular procedures under regional anaesthesia, sedation was induced with propofol TCI by increasing target concentrations from 0.9 to 1.3 mg l(-1) by 0.2 mg l(-1) steps up to a sedation score corresponding to light level (patient awakable with tactile stimulation). At baseline and each step, specific pictures were shown to the patient and clinical parameters and unwanted side effects occurrence were recorded. In PACU, memorisation of pictures and events was looked for.
Results: Conscious sedation was obtained in 100% of the patients at 0.9 mg l(-1), 94% at 1.1 and 78% at 1.3 mg l(-1). Amnesia was concentration-dependent and for each concentration was always more important for pictures than for events. Haemodynamic parameters did not change significantly. Incidents occurred in 12% of cases at 1.1 and 39.4% at 1.3 mg l(-1).
Discussion: None of those three concentrations was satisfying in 100% of cases for the three criterias (sedation < S2, amnesia and none side effects). These results suggest that propofol target concentration 0.9 microg ml(-1) could be used safely for sedation in elderly ASA III patients. Moreover, we have shown that amnesia for events requires higher propofol concentrations than amnesia for pictures during conscious sedation.