The Combined Use of the Timing Principle and LMA to Secure Airway Patency

Abstract

Background: The timing principle uses a single bolus dose of nondepolarizing neuromuscular blocker followed by an induction drug to reduce airway patency secure time. If anesthetic depth is adequate, the laryngeal mask airway (LMA) can be inserted with or without a low dose nondepolarizing neuromuscular blocker. So we investigated the combined use of the timing principle and LMA to secure airway patency. Methods: One hundred and two patients were randomly allocated into three groups. Group RP (n = 34) patients received rocuronium followed by propofol and then a LMA was inserted. Group PR (n = 36) patients received propofol followed by rocuronium and group PS (n = 31) patients received propofol followed by succinylcholine before LMA insertion. Accelerographic response to single twitch and train-of-four (TOF) stimulation were measured. LMA insertional conditions were measured using the degree of jaw relaxation, gagging, cough, and aeration. Results: Single twitch and TOF ratio were lower in the RP group than in the PR group. The LMA insertional conditions were similar for the group RP and PS, but were poor for group PR. One patient in group PR recalled discomfort during LMA insertion. Conclusions: The combined use of the timing principle and LMA is effective at securing airway patency.