Pressure transmission in the upper airways during Inspiratory muscle training (IMT).

<bold>Introduction:</bold> Laryngoscopy has revealed variable laryngeal responses to Inspiratory Muscle Training (IMT), where higher resistances might lead to adverse vocal fold adduction. Maximal inspiratory pressure (MIP) manoeuvres are used to guide IMT pressure settings. To effectively use IMT in treating patients with Exercise-Induced Laryngeal Obstruction (EILO), we need better insight into the dynamics of pressure transmission within the upper airways during a MIP manoeuvre. <bold>Aims:</bold> To address feasibility of measuring pressures in the trachea during MIP manoeuvres, and to investigate the pressure transmission within the upper airways in healthy volunteers. <bold>Methods:</bold> Ten healthy volunteers were included in this cross-sectional study. Pressure was measured: 1) by the mouthpiece (PowerBreath KHP②), 2) above the larynx (epiglottis) and 3) in the trachea (pressure transducers positioned via trans-nasal fiberoptic laryngoscopy). The participants performed 3-10 MIP manoeuvres until they reached their peak MIP. <bold>Results:</bold> Ten adults (6 females), aged 23-65 years performed in total 48 MIP manoeuvres. Findings presented in Table 1. <table-wrap><object-id>erj;64/suppl_68/PA4142/T1</object-id><object-id>T1</object-id><object-id>t1</object-id><table><colgroup><col></col><col></col><col></col><col></col></colgroup><tbody><tr><td>Sensor position</td><td>Mean cm H₂O ± SD</td><td>Minimum MIP cm H₂O</td><td>Maximum MIP cm H₂O</td></tr><tr><td>Mouthpiece</td><td>−81.76 ± 25.6</td><td>−30.31</td><td>−137.6</td></tr><tr><td>Epiglottis</td><td>−85.41 ± 25.6</td><td>−37.72</td><td>−140.9</td></tr><tr><td>Trachea</td><td>−86.05 ± 24.3</td><td>−39.66</td><td>−139.4</td></tr></tbody></table></table-wrap> Table 1: Maximal inspiratory pressures (MIP), measured at the mouthpiece, epiglottis, and trachea. <bold>Conclusions:</bold> Measuuring tracheal pressure during MIP is possible. Mean pressures were more negative in the trachea than at the mouthpiece, with high standard deviations. The large variability needs to be addressed in future studies, as this may be related to variable laryngeal responses.