This observational cohort study will characterise the temporal profile of the anti-nociceptive effect of an intravenous ketamine bolus using the Nociception Analgesia Index (ANI).
This prospective observational cohort (n=20) will record ANI continuously around a single IV ketamine bolus in patients scheduled for elective surgery under general anaesthesia to describe the time course of the anti-nociceptive effect.
PKPD modelling will use the Domino pharmacokinetic model and an Emax link model with a ke0 to relate predicted effect-site concentrations to ANI changes; analyses performed with NONMEM. ANI will be sampled every 6 seconds for 5 minutes after the bolus.
Single IV ketamine bolus with ANI monitoring to characterise anti-nociceptive time profile.
1 mg/ml bolus; followed by 5 ml saline flush; ANI recorded every 6 seconds for 5 minutes.