Purpose: The chin down posture is a compensatory strategy commonly used to minimize the risk of aspiration in patients with a pharyngeal delay. There are several difficulties to determining if the chin down posture is effective at eliminating aspiration including: the variability on how to perform the posture, what the posture is called, and the anatomical changes resulting from the posture The main purpose of this study was to determine the anatomical changes associated with different postural positions (i.e., chin down, chin tuck, and head extended) using endoscopy.
Method: Twenty healthy female subjects underwent nasoendoscopy and assumed four different head positions with and without a bolus in the oral cavity. Subjects were instructed on how to perform each posture prior to insertion of the endoscope. The four head position included a neutral, chin down (looking at the floor), chin tuck (chin to neck), and head extended position. Still images of each posture and condition were analyzed using ImageJ to measure the changes in area of airway opening and in distance between structures (e.g., posterior pharyngeal wall to epiglottis). Measured distances and area changes across postures were analyzed within and across subjects. Statistical and descriptive analyses were also completed.
Results & Conclusions: The findings demonstrated that there are statistically significant differences in the anatomical structures of the pharynx when creating the chin down, chin tuck, and head extended positions. Furthermore, the presence of a small liquid bolus in the oral cavity played a significant role in changing the area observed in all postures compared to the non-bolus hold postures. Although we were unable to determine a significant statistical difference between the chin down and chin tuck postures, descriptive analyses of these postures lead to noticeable trends in airway opening and visible anatomy (e.g., laryngeal vestibule, vallecular space) across subjects. The chin tuck posture was found to provide subjects with the greatest decrease in area of airway opening from the neutral position, thus increasing airway protection.