Effect-site concentration of propofol required for LMA-Supreme™ insertion with and without remifentanil: A randomized controlled trial

Abstract

Background: A new supraglottic device, the LMA-Supreme™, has recently become available for clinical use. Information on anaesthetic and co-adjuvant requirements for insertion of the LMA-Supreme™ is limited. The present study aimed to evaluate the optimal effect-site concentration of propofol in 50 % (EC50) of adults necessary for successful insertion of the LMA-Supreme™ and to examine remifentanil's effect on propofol requirements. Methods: Fifty-eight elective patients (aged 18-60 years; ASA (American Society Anaesthesiologists) physical status classification I and II) scheduled for day surgery were randomly assigned to one of two groups: propofol with saline or propofol with remifentanil. Anaesthesia was induced by target-controlled infusion according to predetermined effect-site concentrations of propofol and remifentanil (5 ng.mL-1). The EC50 was calculated using Dixon's up-and-down method. Ten minutes following drug administration, LMA-Supreme™ insertion was attempted without the use of muscle relaxant drugs. Results: In the propofol + saline group, the EC50 of propofol required for LMA-Supreme™ insertion was 6.32 ± 0.67 μg.mL-1 (95 % CI, 5.69-6.94 μg.mL-1). With the addition of remifentanil at an effect-site concentration of 5 ng.mL-1, the EC50 of propofol required for LMA-Supreme™ insertion was 2.50 ± 0.80 μg.mL-1 (95 % CI, 1.82-3.17 μg.mL-1; p < 0.0001). Conclusions: The propofol requirement for smooth insertion of the LMA-Supreme™ was 60 % less when remifentanil (5 ng.mL-1) was co-administered. Clinical trial registration: Identified as NCT01974648at www.clinicaltrials.gov.