Fiberoptic assessment of the Laryngeal Mask Airway (Laryseal) position after one hour of positive pressure ventilation: an observational study

Abstract

Study objectives: To determine, by fiberoptic endoscope, malpositioning of the Laryngeal Mask Airway (LMA) and other extraglottic devices.

Design: Prospective study.

Setting: University-affiliated medical center.

Patients: 60 adult, ASA physical status 1 and 2 patients, aged 20 - 60 years, scheduled to undergo ophthalmic procedures with general anesthesia during controlled ventilation via LMA (Laryseal).

Measurements: Adequacy of ventilation was determined by the absence of audible leak and appropriate capnograph trace. Fiberoptic assessment and imaging of LMA position were done after proper insertion of the LMA and after one hour of positive pressure ventilation (PPV). Assessment included position of the epiglottis, glottis, and cuff.

Main results: The epiglottis was visible in 50 patients (83.3%). Vocal cords were visible in 58 patients at the time of insertion, and in 52 patients after one hour of PPV (P = 0.047). The arytenoids were herniating through the mask aperture after one hour of PPV (P = 0.0132). The cuff position was less optimal after one hour of controlled ventilation (P = 0.032).

Conclusion: LMA position may change spontaneously with time during PPV, especially when the LMA position is not optimum at the time of insertion. The LMA should be adequately inserted with all possible measures in cases with general anesthesia and PPV. Fiberoptic assessment of LMA position intraoperatively may be advantageous.

Keywords: Fiberoptics; Laryngeal Mask Airway; Positive pressure ventilation.