Respiratory Angle of Thoracic Wall Movement During Lung Ventilation

This paper assesses chest wall mechanics with emphasis on sternum movement during lung ventilation. Such activity distorts the thoracic wall by moving it outward and upward, creating an acute angle in the sagittal plane. The respiratory angle is defined and measured by a set of 3-D optical tracking system with an accuracy of 100 μm. It emits 850-nm infrared lights and picks up motions of a marker array attached on the chest. First-degree polynomial fitting was used in order to calculate the respiratory angle from the 3-D marker trajectories. A group of 20 subjects were recruited in the human testing, from which a range of 33.69°-67.67° were determined. The standard deviation of each estimation ranged from 1.28° to 14.15°. The mean for all 20 estimates was 50° of respiratory angle. The study of respiratory angle may enable the optimal positioning of respiratory effort harvesters, increase sensitivity of physiological radar sensors, and enhance the resolution of different imaging modalities.