The influence of gravity on respiratory kinematics during phonation measured by dynamic magnetic resonance imaging

Louisa Traser,Fabian Burk,Michael Bock,Matthias Echternach,Carmen Schwab,Ali Caglar Özen,Michael Burdumy,Bernhard Richter

doi:10.1038/s41598-021-02152-y

Abstract

Respiratory kinematics are important for the regulation of voice production. Dynamic MRI is an excellent tool to study respiratory motion providing high-resolution cross-sectional images. Unfortunately, in clinical MRI systems images can only be acquired in a horizontal subject position, which does not take into account gravitational effects on the respiratory apparatus. To study the effect of body posture on respiratory kinematics during phonation, 8 singers were examined both in an open-configuration MRI with a rotatable gantry and a conventional horizontal MRI system. During dynamic MRI the subjects sang sustained tones at different pitches in both supine and upright body positions. Sagittal images of the respiratory system were obtained at 1–3 images per second, from which 6 anatomically defined distances were extracted to characterize its movements in the anterior, medium and posterior section of the diaphragm as well as the rip cage (diameter at the height of the 3rd and 5th rip) and the anterior–posterior position of the diaphragm cupola. Regardless of body position, singers maintained their general principles of respiratory kinematics with combined diaphragm and thorax muscle activation for breath support. This was achieved by expanding their chest an additional 20% during inspiration when singing in the supine position but not for sole breathing. The diaphragm was cranially displaced in supine position for both singing and breathing and its motion range increased. These results facilitate a more realistic extrapolation of research data obtained in a supine position.

Highlights

Respiratory kinematics are important for the regulation of voice production
Its primary task is the regulation of subglottic pressure, caused by the expiratory force of the respiratory system applied to the vocal folds
A differentiated pattern of movements of the respiratory system was revealed, which was very different from pure exhalation: for continuous adjustment of subglottic pressure to the prevailing passive recoil forces, a combined adaptation of inspiratory activity occurred in the thorax and diaphragm

Summary

Introduction

Respiratory kinematics are important for the regulation of voice production. Dynamic MRI is an excellent tool to study respiratory motion providing high-resolution cross-sectional images. Regardless of body position, singers maintained their general principles of respiratory kinematics with combined diaphragm and thorax muscle activation for breath support. This was achieved by expanding their chest an additional 20% during inspiration when singing in the supine position but not for sole breathing. The DPH can compensate to some extent for the associated cranial displacement of the abdominal contents by increasing its contractile force This in turn fits that Hixon et al described a fundamental change in the respiratory kinematics for phonation in a supine body position from mixed to sole DPH mediated inspiratory activation in untrained s ubjects[15]. The aim of this study is to enable a more realistic extrapolation of research results obtained of a supine position, as well as to consider the implications of these findings for voice pedagogy

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Conclusion