Glottic insertion of the ProSeal™ LMA occurs in 6% of cases: A review of 627 patients

Abstract

Purpose: Glottic insertion of the ProSeal™ Laryngeal Mask Airway (PLMA) has received little attention in the anesthesiology literature. We investigated the incidence and depth of insertion associated with this important cause for a failed insertion attempt with the PLMA. Methods: With Institutional Review Board approval, we reviewed 15-months' use of the PLMA. Diagnosis of glottic insertion involved a test with children's bubble solution placed on the drain tube port, as well as a fibreoptic examination of the airway of patients experiencing airway obstruction. Patients were anesthetized and paralyzed and the PLMA was inserted deflated with the fingertip method (women size 4, men size 5). The cuff was inflated and a soap membrane established on the drain tube port. Glottic insertion was diagnosed by applying fingertip pressure to the patient's chest wall and observing pulmonary exhalation via the drain tube and bubble formation. The PLMA was then removed and reinserted without further assessment. For all patients, we used a fibrescope to determine the cause of unexplained airway obstruction after the PLMA was considered successfully inserted. Results: There were 627 patients (391 women, 236 men). We diagnosed glottic insertion in 38/627 (6.1%) patients, 37 by the soap membrane test and one with airway obstruction and direct fibreoptic visualization of malposition. Following glottic insertion, successful reinsertion of the PLMA behind the larynx was always associated with greater depth of insertion by an average 2.0 cm. Conclusion: Glottic insertion can be easily and quickly diagnosed and our results suggest the incidence and importance of malposition are under-reported in the literature.