Sevoflurane requirements for tracheal intubation with and without fentanyl

Abstract

We studied 80 healthy ASA 1 patients (aged 20-52 yr) to determine if fentanyl affects sevoflurane requirements for achieving 50% probability of no movement in response to laryngoscopy and tracheal intubation (MAC-TI). Patients were allocated randomly to one of four fentanyl dose groups (0, 1, 2 and 4 micrograms kg-1). Patients in each group received sevoflurane at a pre-selected end-tidal concentration according to an 'up-down' technique. After steady state sevoflurane concentration had been maintained for at least 10 min, fentanyl was administered i.v. Tracheal intubation was performed 4 min after administration of fentanyl, and patients were assessed as moving or not moving. Heart rate (HR) and mean arterial pressure (MAP) were recorded before induction of anaesthesia, just before administration of fentanyl, just before laryngoscopy for intubation, and after intubation. The MAC-TI of sevoflurane was 3.55% (95% confidence intervals 3.32-3.78%), and this was reduced markedly to 2.07%, 1.45% and 1.37% by addition of fentanyl 1, 2 and 4 micrograms kg-1, with no significant difference in the reduction between 2 and 4 micrograms kg-1, showing a ceiling effect. Fentanyl attenuated haemodynamic responses (HR and MAP) to tracheal intubation in a dose-dependent manner, even with decreasing concomitant sevoflurane concentration. Fentanyl 4 micrograms kg-1 suppressed the changes in HR and MAP more effectively than fentanyl 1 or 2 micrograms kg-1 at sevoflurane concentrations close to MAC-TI.

Low alfentanil target-concentrations improve hemodynamic and intubating conditions during induction with sevoflurane

“…1,6 Because opioids decrease sevoflurane minimum alveolar concentration (MAC) and heart rate, they may reduce hemodynamic changes and time to tracheal intubation. [7][8][9][10] However asystole or severe hypotension may occur, probably because of inappropriate opioid dosing, and the effects of sevoflurane-alfentanil on the ease and speed of tracheal intubation have not been evaluated. 9,[11][12][13] Our study aimed to determine the dose of alfentanil required to decrease the time to tracheal intubation and blunt the increase in heart rate associated with an inhalation induction.…”

“…9 While maintaining a steady state concentration of sevoflurane, the MAC for tracheal intubation is reduced by 42% when adding 1 µg·kg -1 fentanyl. 8 The maintenance of a steady state concentration of sevoflurane used in these previous studies is relevant only for maintenance of anesthesia but not for induction. In the present study, we chose a different approach, maintaining alfentanil at steady state concentrations.…”

Low-dose fentanyl-midazolam combination improves sevoflurane induction in adults

“…The MAC-sparing effect of both fentanyl 12 and midazolam 13,14 can probably explain these results. Still, authors who have studied the administration of opioids or midazolam alone prior to IIAS have found conflicting results.…”

“…Still, authors who have studied the administration of opioids or midazolam alone prior to IIAS have found conflicting results. Some showed increased [7][8][9][10][11][12][13][14][15] time to loss of consciousness or time needed before laryngeal mask insertion, while others showed a decrease. [5][6][7][8][9][10] The choice of drugs and doses in this study was influenced by Muzi et al 10 who showed that this particular combination accelerated and improved conditions for endotracheal intubation.…”

A Comparison of Propofol With Sevoflurane and Propofol Alone for Induction and Intubation

“…Fentanyl also has anti tussive action. Katohet al 22 suggested that fentanyl blocks afferent nerve impulses arising from stimulation of the pharynx, larynx and lungs during intubation.…”