Remifentanil TCI in patients breathing spontaneously TCI for painful surgical procedure with spontaneous breathing

摘要

Why remifentanil and why Target Controlled Infusion in this context? Remifentanil is a mu-agonistopioid sharing with other opioids all their pharmacological effects as dose-dependant analgesia (expected effects), very low sedative effects, but also respiratory depression, sympathetic blockade, chest rigidity, nausea and vomiting ...(1). Its benefits come for its pharmacokinetics properties. First, its onset is short (< 2 minutes), as short as alfentanil but shorter than all others. Above all, its concentration decreases rapidly (i.e. effects are rapidly reversible) without accumulation whatever the duration of infusion (2). For these reasons, it is especially suitable for acute, short duration painful procedures (because of its onset) and when the therapeutic margin between adequate analgesia and adverse effects (as apnea) is low and the doses should be titrated easily (because of its offset) (3). However, these properties are true only when bolus doses, infusion rates and stops are properly chosen to minimize the delay from changing the setting to achieve a pseudo-plateau in concentration at effect site, which is not easy manually especially when several adjustments are necessary. Target Controlled infusion is therefore a major improvement in this context because it takes into account both the pharmacokinetic parameters of the drug and the infusions rate history to achieve a chosen concentration without overshoot (4).