Head elevation by 3 vs. 6 cm in ProSeal laryngeal mask airway insertion: a randomized controlled trial

BACKGROUND: The sniffing position (neck flexion by head elevation and head extension) is commonly used for insertion of a laryngeal mask airway. However, the appropriate degrees of head elevation and head extension are unclear. In the present study, the success rate of ProSeal™ laryngeal mask airway (LMA ProSeal) insertion using two degrees of head elevation was evaluated. METHODS: This prospective randomized, controlled study included 80 adult patients aged 18 to 90 years. In the 3 cm (n = 40) and 6 cm (n = 40) groups, the LMA ProSeal was inserted while the head was elevated 3 cm and 6 cm, respectively, using a pillow of the corresponding height. The success rate, and incidence of blood staining on cuff, sore throat and hoarseness were assessed. The alignments of laryngeal and oral axes were also evaluated. RESULTS: The first attempt success rate was higher in the 3 cm than the 6 cm group (87 % vs. 60 %, P = 0.014). In 86 % of patients in the 6 cm group and 50 % of patients in the 3 cm group in whom the second attempt failed, the third insertion attempt was successful by using a pillow height of the opposite group. The alignments of the two axes were not different between the two groups (P > 0.05). CONCLUSIONS: The first attempt success rate of ProSeal laryngeal mask insertion was higher with 3 cm than 6 cm head elevation in adult patients. TRIAL REGISTRATION: Identifiers: NCT02058030 (08/05/2015), Unique Protocol ID: phdkim1.