Comparison between the Airgo™ Device and a Metabolic Cart during Rest and Exercise

Abstract

The aim of this study is to compare the accuracy of Airgo™, a non-invasive wearable device that records breath, with respect to a gold standard. In 21 healthy subjects (10 males, 11 females), four parameters were recorded for four min at rest and in different positions simultaneously by Airgo™ and SensorMedics 2900 metabolic cart. Then, a cardio-pulmonary exercise test was performed using the Erg 800S cycle ergometer in order to test Airgo™’s accuracy during physical effort. The results reveal that the relative error median percentage of respiratory rate was of 0% for all positions at rest and for different exercise intensities, with interquartile ranges between 3.5 (standing position) and 22.4 (low-intensity exercise) breaths per minute. During exercise, normalized amplitude and ventilation relative error medians highlighted the presence of an error proportional to the volume to be estimated. For increasing intensity levels of exercise, Airgo™’s estimate tended to underestimate the values of the gold standard instrument. In conclusion, the Airgo™ device provides good accuracy and precision in the estimate of respiratory rate (especially at rest), an acceptable estimate of tidal volume and minute ventilation at rest and an underestimation for increasing volumes.

Assessing the Tidal Volume through Wearables: A Scoping Review

“…In studies dealing with quasi-static motor tasks, the relative volumetric error averaged across the subjects, expressed as a percentage of the volume measured by the reference measurement tool (see RelErr in Table 4 ), was typically lower than 20%. Noticeably, in some cases, the RelErr fell below 5% [ 31 , 38 , 58 ], whereas, in one case, values appeared to be significantly higher (+35%; [ 57 ]). When the volumetric error was assessed as the difference between estimated and reference values (see MOD in Table 4 ), the authors typically reported an averaged bias across enrolled participants lower than 0.1 L. Very often, the bias was one order of magnitude lower, whereas, in some cases, it had significantly higher values (e.g., from 0.7 to 5 L; [ 43 ]).…”

“…Six reviewed studies dealt with the assessment of the tidal volume measured by resistive stretch sensors ( Table 2 ) [ 6 , 31 , 35 , 45 , 46 , 51 ]. Two of these studies [ 31 , 35 ] tested the accuracy of a commercial device, namely Airgo TM , while estimating the tidal volume in quasi-static (e.g., standing, sitting, and supine) and dynamic (i.e., cycling) motor tasks ( Table 3 ). Airgo TM is a standalone sensory platform consisting of an extensible band designed to provide a signal proportional to the thoracic circumference.…”

“…Given the relevance of the tidal volume, we designed a scoping review aiming to identify research evidence supporting the use of wearable devices to continuously monitor the tidal volume in both daily activities and clinical settings. In more detail, this study was conceived to do the following: (i) highlight the available technology; (ii) clarify the accuracy of the proposed methodological approaches with respect to the experimental conditions (e.g., resting on a bed vs. cycling), as they do affect cardio-respiratory functions [ 30 ] and related assessments [ 31 ]. In a long-term perspective, this study is expected to contribute to the definition of novel methodological paradigms for an accurate assessment of the tidal volume, which can be used for either the daily monitoring of the users’ status or the development of adaptive respiratory treatments.…”

Smart Textiles and Sensorized Garments for Physiological Monitoring: A Review of Available Solutions and Techniques

“…In the literature, e-textiles including respiratory sensors have been largely studied [ 51 ]. A limitation that is found in wearable devices based on the variation of the thoracic dimension is that measurements are acquired in one spot of the chest wall, i.e., only one degree of freedom is considered in the model [ 66 ], while it is known from the literature that the rib cage and the abdomen give different contributions to the tidal volume with changing postures [ 67 ]. For this reason, garments that can embed multiple respiratory sensors in different positions allow to obtain more accurate measurements.…”

A Wearable Device for Breathing Frequency Monitoring: A Pilot Study on Patients with Muscular Dystrophy

“…Continuous measurement of respiratory rate can be achieved by non-intrusive wearable devices. This consists of deriving a respiratory-related signal by detecting the motion of the thoraco-abdominal surface by inductive [ 14 ], resistive [ 15 , 16 , 17 ], or capacitive sensors [ 18 ]. More recently, smart textiles embedding fiber optic sensors, namely fiber Bragg grating (FBG) sensors positioned at different body locations, have also been proposed for respiratory monitoring [ 19 ].…”