Anaesthetic BlockIntensive Care SocietyRamsay ScoreEstablished RegimenLocal Ethic Approval
The principal objective of this multicentre, non-comparative study was to determine the range of target blood propofol concentration settings required when 'Diprifusor' TCI systems are used to administer propofol for sedation in ventilated, adult, ICU patients. Following local ethics approval, data were obtained from 122 patients. Informed consent was obtained from patients or their next of kin. Three categories of ICU patients were studied: 57 post-cardiac surgery, 18 brain injured and 47 general ICU. Mean ages were 60.7, 41.1 and 60.7 years and mean APACHE II scores 9.2, 17.8 and 19 in the three groups respectively. The mean duration of sedation was 15 hours in the post-cardiac surgery patients, 47.6 hours in the brain injured group and 63.3 hours in the general ICU group. All post-cardiac surgery patients had received propofol by Diprifusor TCI for surgery and the same TCI system continued in use for sedation. Patients were excluded if they had received propofol by conventional modes of administration within 4 hours of the start of the study, had an established regimen of sedation with agents other than propofol for more than 24 hours, or a regional anaesthetic block persisting into the period of sedation. Depth of sedation was assessed with a modified Ramsay Score (UK Intensive Care Society National Guideline, 1999) and was also graded as light (L), desired level (D) or excessive (E). The 'Diprifusor' target blood propofol setting was titrated as required to obtain the depth of sedation desired in each patient. A desired level of sedation was obtained, after a mean time of 9.9 min, in all but one patient in whom sedation was 'excessive' throughout. For each patient, the time-weighted average target setting over the entire period of sedation, from the time when a desired level was first obtained, was calculated. Median, 10th and 90th percentile values are presented in Table 1.
Time-weighted average Diprifusor target blood propofol settings (μg/ml)