Assessing Orthotic Normalization of Pharyngeal Dynamics

The size and behavior of the human upper airway during inhalation of aerosols

INTRODUCTION

The mouth, the pharynx and the larynx are potential sites of aerosol deposition in the upper airway during inhalation of aerosolized drugs. The right angle bend of the lumen at the back of the mouth, the position of the tongue, the variable size and shape of the lumen in the pharynx and the larynx, and the breathing pattern could increase aerosol deposition in the upper airway and decrease lung deposition. Areas covered: In this review, the anatomy of the upper airway from the oral cavity to the glottis and the impact of mandibular protrusion and incisal opening on the size of the upper airway are highlighted. In addition, the impact of inhalation maneuvers, inhaler mouthpiece geometries and a stepped mouthpiece on the size of the upper airway are discussed. Expert opinion: The structure of the upper airway lumen does not have a fixed cross sectional area and is susceptible to both constriction and distension during inhalation. The size of the upper airway can be enlarged through mandibular protrusion and/or incisal opening which might decrease aerosol deposition in the upper airway and increase lung deposition.

Use of a sibilant phoneme registration protocol to prevent upper airway collapse in patients with TMD

Patients with temporomandibular dysfunction (TMD) require antero-posterior (AP) correction of mandibular position inter alia. Determination of the limit of the AP correction using a sibilant phoneme registration (SPR) protocol is essential in not increasing muscular tonus. The aim of this study is to investigate the effect of a SPR protocol on the upper airway. Using acoustic pharyngometry data, mean airways of 46 adults undergoing treatment for TMD were reconstructed in 3-D and analyzed using finite element analysis and principal components analysis. When the mean baseline functional residual capacity (FRC) airway was compared to the mean collapsed residual volume (RV) airway, a 25% reduction in the 3-D upper airway was demonstrable (p < 0.01). When the mean baseline FRC airway was compared to the mean airway with SPR (FRC-SPR), a 12% increase was found at the oropharyngeal junction of the 3-D airway, but this finding failed to reach statistical difference. Similarly, when the mean FRC-SPR airway was compared to the mean RV-SPR airway, the amount of collapse was reduced to 16% but again no statistical difference was found. In contrast, when the mean RV airway was compared to the mean RV-SPR airway, a 15-18% increase was found (p < 0.05). It is concluded that the use of a SPR protocol may be useful in improving upper airway RV in patients, during treatment for TMD.