Characterisation and Quantification of Upper Body Surface Motions for Tidal Volume Determination in Lung-Healthy Individuals

Abstract

Measurement of accurate tidal volumes based on respiration-induced surface movements of the upper body would be valuable in clinical and sports monitoring applications, but most current methods lack the precision, ease of use, or cost effectiveness required for wide-scale uptake. In this paper, the theoretical ability of different sensors, such as inertial measurement units, strain gauges, or circumference measurement devices to determine tidal volumes were investigated, scrutinised and evaluated. Sixteen subjects performed different breathing patterns of different tidal volumes, while using a motion capture system to record surface motions and a spirometer as a reference to obtain tidal volumes. Subsequently, the motion-capture data were used to determine upper-body circumferences, tilt angles, distance changes, movements and accelerations—such data could potentially be measured using optical encoders, inertial measurement units, or strain gauges. From these parameters, the measurement range and correlation with the volume signal of the spirometer were determined. The highest correlations were found between the spirometer volume and upper body circumferences; surface deflection was also well correlated, while accelerations carried minor respiratory information. The ranges of thorax motion parameters measurable with common sensors and the values and correlations to respiratory volume are presented. This article thus provides a novel tool for sensor selection for a smart shirt analysis of respiration.

Sensor Selection for Tidal Volume Determination via Linear Regression—Impact of Lasso versus Ridge Regression

“…Hence, there remains a need for alternative methods for measuring respiratory volumes using upper body surface motion. A previous study [3] has shown that upper body movements are in some cases highly correlated with changes in respiratory volumes. This fact can be utilized for the determination of respiratory volumes via upper body movements, and some current approaches used inertial measurement units [18][19][20], others used strain gauges [21,22] or optical encoder systems, as in belts measuring changes in circumferences [23][24][25].…”

“…The study was based on the data recorded in Laufer et al [3], where a motion capture system (MoCap) (Bonita, VICON, Denver, CO, USA) with nine infrared cameras (VICON Bonita B10, firmware version 404) was used to measure the respiratory-induced movements of the human upper body via 102 highly reflective motion capture markers, attached at precise locations on a compression shirt. A schematic of the measurement system is shown in Figure 1.…”

“…Respiration-induced motions were studied as early as 1848 by Sibson et al [1]. Later, Wade et al [2] used improved measurement methods and examined the respiratoryinduced movements of the upper body, and recently, Laufer et al [3] analyzed movement parameters of the upper body and their correlations with the respiratory volume in detail.…”

“…The MoCap system allows for the determination of various movement parameters of the upper body, such as accelerations, displacements and tilt angles at various surface points. Furthermore, upper body circumferences and local distance changes between the points can be determined [3]. These movement parameters can be measured via corresponding sensors.…”

“…Breathing of different tidal volumes-shallow (2), medium (4) and maximal breaths (6) between short ranges of normal spontaneous breathing ((1), (3), (5) and (7)). Figure published in[3].…”