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. 2015 Jul;56(4):1128-33.
doi: 10.3349/ymj.2015.56.4.1128.

Predicted EC₅₀ and EC₉₅ of Remifentanil for Smooth Removal of a Laryngeal Mask Airway Under Propofol Anesthesia

Ji Young Yoo  1 , Hyun Jeong Kwak  2 , Kyung Cheon Lee  2 , Go Wun Kim  1 , Jong Yeop Kim  3
Affiliations

Predicted EC₅₀ and EC₉₅ of Remifentanil for Smooth Removal of a Laryngeal Mask Airway Under Propofol Anesthesia

Ji Young Yoo et al. Yonsei Med J. 2015 Jul.

Abstract

Purpose: The purpose of this study was to determine the effect-site concentration (Ce) of remifentanil in 50% of patients (EC₅₀) and 95% of patients (EC₉₅) for smooth laryngeal mask airway (LMA) removal in adults under propofol and remifentanil anesthesia.

Materials and methods: Twenty-five patients of ASA physical status I-II and ages 18-60 years who were to undergo minor gynecological or orthopedic surgery were assessed in this study. Anesthesia was induced and maintained with propofol and remifentanil target-controlled infusion (TCI). Remifentanil was maintained at a predetermined Ce during the emergence period. The modified Dixon's up-and-down method was used to determine the remifentanil concentration, starting from 1.0 ng/mL (step size of 0.2 ng/mL). Successful removal of the LMA was regarded as absence of coughing/gagging, clenched teeth, gross purposeful movements, breath holding, laryngospasm, or desaturation to SpO₂<90%.

Results: The mean±SD Ce of remifentanil for smooth LMA removal after propofol anesthesia was 0.83±0.16 ng/mL. Using isotonic regression with a bootstrapping approach, the estimated EC₅₀ and EC₉₅ of remifentanil Ce were 0.91 ng/mL [95% confidence interval (CI), 0.77-1.07 ng/mL] and 1.35 ng/mL (95% CI, 1.16-1.38 ng/mL), respectively.

Conclusion: Our results showed that remifentanil TCI at an established Ce is a reliable technique for achieving safe and smooth emergence without coughing, laryngospasm, or other airway reflexes.

Keywords: Laryngeal mask airway; device removal; effect-site concentration; general anesthesia; remifentanil; target-controlled infusion.

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Conflict of interest statement

The authors have no financial conflicts of interest.

Figures

Fig. 1
Fig. 1. The responses of 25 patients to laryngeal mask airway removal and the remifentanil concentration. Arrows represent the midpoint doses of all independent pairs of patients involving a crossover (i.e., success to failure). The remifentanil concentration required for smooth removal in 50% of the patients was 0.83±0.16 ng/mL.
See this image and copyright information in PMC

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