Influence of head and neck position on the performance of supraglottic airway devices: A systematic review and meta-analysis.

The reduced oropharyngeal leak pressure in the extended neck position was not associated with impaired ventilation except with the air-Q self-pressurizing airway. The flexed neck position significantly worsens ventilation and the alignment between the SAD and glottis despite improving the seal except with the air-Q self-pressurizing airway and LMA Proseal.