Evaluation of the Adequacy of Using the Supraglottic Airway Device (i-gel®) in Cases With Epiglottic Masses: A Mannequin Simulation Study

Background: Epiglottic masses are often asymptomatic, making them difficult to detect during preoperative examinations. Consequently, anesthesiologists may face ventilation difficulties with no apparent cause. Epiglottic masses can sometimes obstruct laryngoscope insertion into the epiglottic vallecula, complicating general anesthesia induction. In such cases, supraglottic airway insertion may be a viable alternative; however, the limited case reports on its use for epiglottic masses make its applicability unclear. Therefore, we test the hypothesis that a larger laryngeal artificial mass could obstruct the view of the larynx, even when supraglottic airways are used in a mannequin study.

Methods: We utilized an airway management simulator (Air Sim Multi®: Nihon 3B Scientific, Japan) to place various sizes of artificial masses (tumors) above the epiglottis. The groups included a control group with no mass, small size mass group, middle size mass group, and large size mass group. The supraglottic airway (i-gel®: Intersurgical, UK) was then inserted 10 times. We categorized the view of the vocal cords using a bronchoscope inserted through the tip of the cuff according to the Cormack-Lehane classification. In addition, we performed pressure-controlled ventilation, adjusting the inspiratory pressure from 10 cm H₂O to 25 cm H₂O, while measuring the tidal volumes.

Results: The Cormack-Lehane classification grade increased in correlation with the mass size. In each inspiratory pressure, tidal volume decreased in correlation with the mass size. Furthermore, in the large-size mass group, even at an inspiratory pressure of 25 cm H₂O, achieving the tidal volume required for general adult respiratory management was deemed difficult.

Conclusion: In a mannequin study, we observed that epiglottic masses significantly increased the Cormack-Lehane classification grade and reduced tidal volume, with these effects correlating with the size of the mass. This finding suggests that the appropriateness of using a supraglottic airway may depend on the size and weight of the epiglottic mass.