Transnasal fiberoptic laryngoscopy (TFL) is gold standard for visualising the larynx. TFL has been used to visualize the laryngeal response patterns during non-invasive therapeutic interventions, as during Mechanically Assisted Cough in patients with Amyotrophic Lateral Sclerosis. The examinations revealed that the larynx adducted during the application of positive pressures, which restricted the airflow and reduced the efficacy of the treatment. The higher treatment pressures resulted in ineffective interventions as a result of the adducted vocal cords obstructing flow. This knowledge has changed the treatment approach for patients with possible upper airway instability by individualizing the treatment pressures and flow due to laryngeal responses.~TFL may cause slight discomfort when placing the laryngoscope. Diagnostic ultrasound is non-invasive easily applicable technique that has gained increasing popularity in diagnosing cardiopulmonary and laryngeal conditions during the recent times. The aim of the study is to investigate whether the diagnostic ultrasound of the larynx can be as accurate as TFL during Mechanically Assisted Cough and Non-Invasive Ventilation (NIV). The present study will include healthy participants. Hypothesis is that diagnostic ultrasound of larynx can provide clinical valuable information of the laryngeal response patterns during Mechanically Assisted Cough and NIV.~The aims of the study are:~To evaluate the feasibility of diagnostic ultrasound imaging of the larynx, and to compare to the gold standard of TFL used during ongoing NIV and Mechanically Assisted Cough in healthy subjects.~To evaluate the feasibility of ultrasound imaging if the diaphragm during ongoing NIV and Mechanically Assisted Cough in healthy subjects.
The study examines if diagnostic ultrasound imaging of larynx and diaphragm can be as accurate as transnasal fiberoptic laryngoscopy in visualizing the larynx during NIV and Mechanically Assisted Cough interventions.