Supreme™ laryngeal mask airway insertion requires a lower concentration of sevoflurane than ProSeal™ laryngeal mask airway insertion during target-controlled remifentanil infusion: a prospective randomised controlled study

Abstract

Background: ProSeal (PLMA) and Supreme (SLMA) laryngeal mask airways are effective ventilator devices with distinctive designs that may require different anaesthetics for insertion. Sevoflurane induction provides acceptable conditions for laryngeal mask insertion, and remifentanil significantly decreases the minimum alveolar concentration of sevoflurane required for that insertion. The study aimed to evaluate the optimal end-tidal (ET) sevoflurane concentration for successful insertion of PLMA versus SLMA in patients receiving a remifentanil infusion without a neuromuscular blocking agent.

Methods: Altogether, 45 patients ASA (American Society Anaesthesiologists) physical status I-II, aged 18-60 years were scheduled for elective ambulatory surgery. Exclusion criteria were a difficult airway, recent respiratory infection, reactive airway, obstructive sleep apnoea syndrome, gastric aspiration's risk factors, pregnancy, and lactation. Patients were randomly allocated to receive the SLMA or the PLMA. Sevoflurane induction with co-administration of remifentanil was performed at an effect-site concentration of 4 ng mL- 1. ET50 was calculated with a modified Dixon's up-and-down method (starting at 2.5% in steps of 0.5%). Predetermined sevoflurane concentration was kept constant during the 10 min before LMA insertion. Patient's response to LMA insertion was classified as "movement" or "no movement". Sevoflurane ET50 was determined as the midpoint concentration of all the independent pairs that manifested crossover from "movement" to "no movement".

Results: The ET50 sevoflurane concentration co-administered with remifentanil required for PLMA insertion was 1.20 ± 0.41% (95% confidence interval 0.76 to 1.63%). For SLMA insertion, it was 0.55 ± 0.38% (95% confidence interval 0.14 to 0.95%) (p = 0.019).

Conclusions: The end-tidal sevoflurane concentration with co-administered remifentanil required to allow insertion of the SLMA was 54% lower than that needed for inserting the PLMA.

Trial registration: Clinicaltrials.gov identifier: NCT03003377. Retrospectively registered. Date of registration: December 28, 2016.

Keywords: End-tidal sevoflurane concentration; Laryngeal mask airway Proseal; Laryngeal mask airway supreme; Remifentanil effect-site concentration; Supraglottic airway devices.

Conflict of interest statement

MZ reports research funding and speaker fees from ABBVIE and Teleflex outside the submitted work. CMM, TG, and MJAB declare no competing interest.

Figures

Fig. 1

Flow-diagram of patient progress through the phases of the trial. Patients were recruited until a sample size of seven crossovers was reached in each group

Fig. 2

Patients’ responses to Laryngeal Mask Airway ProSeal™ insertion. Arrows indicate the midpoint of the effect-site concentration of all independent pairs of patients involving crossover from device insertion failure to successful Laryngeal Mask Airway Airway ProSeal™ insertion

Fig. 3

Patients’ responses to Laryngeal Mask Airway Supreme™ insertion in Arrows indicate the midpoint of the effect-site concentration of all independent pairs of patients involving crossover from device insertion failure to successful Laryngeal Mask Airway Supreme™ insertion

Fig. 4

Dose-response curves plotted from logistic analysis of individual end-tidal sevoflurane concentrations and the respective reactions to PLMA or SLMA insertion. ET50 in PLMA group: 1.15%; ET50 in SLMA group: 0.43%; ET95 in PLMA group: 2.43%; ET95 in SLMA group: 1.50%