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%

Abstract

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 < 0.0001) between groups in concordance with Ce PROP. Heart rate decreased with increasing Ce REMI (p = 0.001). The haemodynamic and arousal responses evoked by laryngoscopy were not significantly different between groups, but Ce PROP = 3.6 μg⋅ml −1 and Ce REMI = 4 ng⋅ml −1 evoked the lowest median value for ∆HR and ∆SAP after laryngoscopy. This study provides clinical insight on the haemodynamic and hypnotic consequences, when a model based predicted P TOL is used as a target for combined effect-site controlled target-controlled infusion of propofol and remifentanil. Heart rate and bispectral index were significantly different between groups despite a theoretical equipotency for P TOL , suggesting that each component of the anaesthetic state (immobility, analgesia, and hypnotic drug effect) should be considered as independent neurophysiological and pharmacological phenomena. However, claims of (in)accuracy of the predicted P TOL must be considered preliminary because larger numbers of observations are required for that goal.

An Open Source Patient Simulator for Design and Evaluation of Computer Based Multiple Drug Dosing Control for Anesthetic and Hemodynamic Variables

“…Developments are covering both intravenous and aerosol management of depth of anesthesia [59], [60]. Influence of Propofol and Remifentanil on the hemodynamic and hypnotic states is further assessed in recent studies [61]. Recently, a novel PKPD model for Propofol has been proposed in [62], yet to be seen if applicable for optimizing closed loop control objectives.…”

A great tool that resurfaced during the pandemic: Remifentanil

“…Furthermore, it has no action on the bispectral index at usual concentrations, while it slows down the electroencephalogram tracing at higher concentrations. 54 Under conditions of normocapnia and maintenance of cerebral perfusion pressure, remifentanil does not increase cerebral blood flow or intracranial pressure. 55 In patients who received a continuous remifentanil infusion, cerebral blood flow increased from 21 to 31 ml/100 g/min.…”

Systematic Application of Rapid Sequence Intubation With Remifentanil During COVID-19 Pandemic

“…5 In fact, in our patients, induced with high dose of remifentanil alone and then combined with only low dose of propofol or midazolam, we did not observe a remarkable hemodynamic effect (namely bradycardia and hypotension) that has often been recorded when remifentanil is used in association with hypnotics at a standard anesthetic dose. 6 In light of the renewed interests generated by the ongoing SARS-Cov-2 pandemic, we are taking advantage of the aforementioned experience, applying it thoroughly to all the patients undergoing cardiac surgery at our institution to achieve a safe RSI in patients who are at risk of cardiovascular compromise.…”

“…5 In fact, in our patients, induced with high dose of remifentanil alone and then combined with only low dose of propofol or midazolam, we did not observe a remarkable hemodynamic effect (namely bradycardia and hypotension) that has often been recorded when remifentanil is used in association with hypnotics at a standard anesthetic dose. 6…”