The feasibility of measuring evoked twitch response of laryngeal adductor muscles by double-cuff endotracheal tube

Objective To investigate the feasibility of monitoring evoked twitch response of laryngeal adductor muscles by double-cuff endotracheal tube during anesthesia.Methods Twenty female patients,aged 20 to 50 years old and scheduled for selective surgical procedure,were enrolled.Anesthesia was induced and maintained with intravenous propofol and sufentanil.A double-cuff endotracheal tube was intubated,the extra cuff of which was placed between the vocal cords and the pressure changes inside the cuff were recorded.After injection of rocuronium 0.3 mg/kg,two TOF Guard monitors were used to stimulate the recurrent laryngeal nerve and the ulnar nerve with superficial electrodes simultaneously.Inhibition and recovery time of evoked twitch responses of the laryngeal adductor muscles and the adductor pollicis were recorded.Results Onset of neuromuscular blockade was faster and recovery was earlier at the laryngeal adductor muscles than those at the adductor pollicis.Lag time and onset time of laryngeal adductor muscles were shorter than those of adductor pollicis(P0.05 or P0.01).Maximal inhibition of laryngeal adductor muscles was lower than those of adductor pollicis(P0.01).The times for T1 to recover to 50%,75% and 90% baseline values and the time for TOF ratio to recover to 0.75 baseline value of the laryngeal adductor muscles were shorter than those of the adductor pollicis(P0.05 or P0.01).Conclusion Monitoring neuromuscular block at the laryngeal adductor muscles with the double-cuff endotracheal tube is reliable and stable.