The Median Effective Dose (ED50) of cis-Atracurium for Laryngeal Mask Airway Insertion during General Anaesthesia for Patients Undergoing Urinary Surgery

Background In clinical practice, the laryngeal mask airway is an easy-to-use supraglottic airway device. However, the cis-atracurium dosage for laryngeal mask insertion has not been standardised. We aimed to determine the optimal dose of cis-atracurium using a sequential method for successful laryngeal mask insertion. Methods The cohort study protocol is registered at clinicaltrial.gov (NCT-03668262). Twenty-three patients undergoing elective urinary surgery were sequentially administered cis-atracurium doses as follows: 150, 100, 70, 50, 30, and 20 μg·kg− 1. The main outcome involved the determination of the response to laryngeal mask airway insertion: ≥16 points and cis-atracurium for laryngeal mask airway insertion. Results The median effective dose of cis-atracurium was 26.5 μg·kg− 1 (95% CI 23.6–29.8) using the sequential method. Heart rate was decreased in the 50 μg·kg− 1 group compared to that in the 30 μg·kg− 1 group at timepoints T7, T8, and T10 (P = 0.0482, P = 0.0460, and P = 0.0236, respectively), but no difference was observed in the 20 μg·kg− 1 group. Systolic blood pressure was decreased in the 50 μg·kg− 1 group compared to that in the 20 μg·kg− 1 group at timepoints T2, T3, and T4 (P = 0.0159, P = 0.0233, and P = 0.0428, respectively). The train-of-four value was significantly lower in the 50 μg·kg− 1 group than in the 30 μg·kg− 1 group at timepoint T3 (P = 0.0326). Conclusions The ED50 of cis-atracurium was 26.5 μg·kg− 1 for laryngeal mask airway insertion. Trial registration Clinicaltrial.gov Registry, NCT03668262, Registered on 11 September 2018.