Comparison of haemodynamic- and electroencephalographic-monitored effects evoked by four combinations of effect-site concentrations of propofol and remifentanil, yielding a predicted tolerance to laryngoscopy of 90

This prospective study evaluates haemodynamic and electroencephalographic effects observed when administering four combinations of effect-site concentrations of propofol (Ce PROP ) and remifentanil (Ce REMI ), all yielding a single predicted probability of tolerance of laryngoscopy of 90% (P TOL = 90%) according to the Bouillon interaction model. We aimed to identify combinations of Ce PROP and Ce REMI along a single isobole of P TOL that result in favourable hypnotic and haemodynamic conditions. This knowledge could be of advantage in the development of drug advisory monitoring technology. 80 patients (18–90 years of age, ASA I–III) were randomized into four groups and titrated towards Ce PROP (Schnider model, ug⋅ml −1 ) and Ce REMI (Minto model, ng⋅ml −1 ) of respectively 8.6 and 1, 5.9 and 2, 3.6 and 4 and 2.0 and 8. After eleven minutes of equilibration, baseline measurements of haemodynamic endpoints and bispectral index were compared with three minutes of responsiveness measurements after laryngoscopy. Before laryngoscopy, bispectral index differed significantly (p