Elsevier

International Journal of Cardiology

Volume 272, 1 December 2018, Pages 231-237
International Journal of Cardiology

Qualitative and quantitative evaluation of a new wearable device for ECG and respiratory Holter monitoring

https://doi.org/10.1016/j.ijcard.2018.06.044Get rights and content

Highlights

  • New wearable complete cardiorespiratory monitoring

  • 12-Lead ECG system and 5 respiratory sensors ambulatory simultaneous recording

  • Excellent quality of ECG and respiratory signals

Abstract

Background

Recent advances in wearable technology make continuous cardiorespiratory monitoring possible, with potential applications in assessment of cardiopulmonary patients, healthy subjects and athletes. The aim of the present study was to qualitatively and quantitatively evaluate a new wearable device (Learn Inspire Free Entertain = L.I.F.E.) by embedding in a compression shirt a 12‑lead ECG system and 5 respiratory sensors.

Methods

Thirty cardiorespiratory patients and ten healthy subjects were studied for 24 h during their usual life activities. In 8 healthy subjects, simultaneous measurements of the device and of an ergo-spirometer were performed during different levels of ventilation in five different body positions. The quality of ECG signals in terms of measurability of heart rate, P wave, QRS complex and ST segment, was analyzed by four expert cardiologists/respiratory physiologists using an arbitrary 1–5 scale. The sum of the respiratory signals was used to calculate the respiratory rate, inspiratory time and relative changes of tidal volume. These parameters were compared to ergo-spirometer measurements.

Results

Median quality value was >3 for heart rate, QRS complex, ST segment and P wave (except in L3, aVL, aVF, V1 and V2 leads). Median quality of respiratory traces was >4 in patients and between 3 and 4 in healthy subjects. The respiratory monitoring of respiratory rate and inspiratory time was accurate in all body positions. Tidal volumes were underestimated due to a high level of ventilation.

Conclusions

The L.I.F.E. device provides an accurate continuous monitoring of cardiorespiratory signals during the 24 h both in normal subjects and cardiorespiratory patients.

Introduction

Cardiorespiratory monitoring is used to assess athletes, normal subjects, and patients with different diseases [1]. It has a pivotal role in patients' management and frequently allows to underscore unexpected clinical conditions or to explain unclear and frightening symptoms [2]. The monitoring is based on two major aspects: a) ECG monitoring and b) respiratory monitoring. Both include day-time and night-time monitoring as well as rest and exercise. ECG monitoring is performed by continuous recording of 1 to 12 ECG leads done for 24 h up to seven days. The recording of ECG traces is usually obtained by electrodes and an external recorder fastened together by cables or by a Wireless technology [3]. In the real world setting, the loss of the signal or poor signal quality is experienced frequently. Respiratory monitoring can detect hypopnea and apnea which is obtained by a nasal flow recorder combined with respiratory movement recorders usually located both at the chest and abdominal level. As for ECG recording, electrodes and cables are required and often lead to failed signal connection and variable signal quality [4, 5].

Learn Inspire Free Entertain (L.I.F.E.) device has been built to simultaneously record ECG and respiratory movement through different sensor elements woven into the fabric of a compressible, self-wearable and washable garment which is even suitable for a residential laundry machine. With a single recording, both ECG Holter and polysomnography data are simultaneously registered with certain advantages. Specifically, apnea/hypopnea induced arrhythmias [[6], [7], [8]] are detectable. In a comprehensive comparability study, several cardiorespiratory monitoring devices have been proposed but none have the characteristics of L.I.F.E. shirt.

The following study was therefore undertaken to assess the overall quality of the ECG and respiratory monitoring by L.I.F.E. shirt. Our assessment, by two independent cardiologists, studies a 24 h period of the quality of the ECG traces as it pertains to heart rate and specific ECG waves in 12 leads. Additionally, five respiratory traces (plus one sum-signal which combines all the respiratory traces) were assessed by two respiratory physiologists in 10 healthy subjects and 30 cardiorespiratory patients. In the healthy volunteers, a comparative analysis between respiratory parameters, assessed by a commercial ergo-spirometer used as gold standard, and L.I.F.E. shirt was performed in different body positions and during different stages of hyperpnea. Simulated obstructive and central apneas were analyzed as well.

Section snippets

Subjects

This is a cross-sectional study performed within the confines of the World Medical Association Declaration of Helsinki. All subjects were recruited from the Centro Cardiologico Monzino (Milan, Italy), from January 2016 to February 2017, and signed an Inform Consent Form. The study was approved by Centro Cardiologico Monzino Ethical Committee (CCM 448). Inclusion criteria were: age 20–80 years and stable clinical conditions. L.I.F.E.

Measurements

L.I.F.E.'s medical compression garment (CE approval n.

Statistical evaluation

All data are expressed as mean ± standard deviation unless otherwise stated. Differences between ventilatory parameters obtained by L.I.F.E. and ergo-spirometer in each maneuver and position were expressed in relative values (i.e. data obtained with L.I.F.E garment minus data obtained during ergo-espirometer divided by data obtained during ergo-espirometer). Data has also been described by means of box plot. Intergroup and intragroup data, regarding respiratory traces and ECG signals, were

Results

As shown in Supplementary Table 1, an overall substantial agreement inter-rater reliability was observed regarding the quality of the respiratory and ECG signals. In the ECG signal, only the QRS complex showed a moderate level of agreement (k = 0.424, p < 0.05).

In Fig. 1, a representative example of all 12-lead ECG and the five respiratory traces (with the sum signal on the bottom right) recorded by L.I.F.E. device is shown. The figure is a screenshot of the monitoring software taken during a

Discussion

This study shows that ECG and respiratory movement monitoring can be performed with high-quality recordings by L.I.F.E. device up to 24 h either in normal subjects and cardiorespiratory patients. For respiratory monitoring, this is not true for high tidal volumes. To the best of our knowledge, L.I.F.E. device is the first cable-less simultaneous 12 ECG leads and respiratory movement recorder, which uses different sensor elements embedded in the fabric of a compressible, easy self-wearable

Conflict of interests

Alessandra Leonardi, Dario Ossola, Rudy Rigoni are L.I.F.E. employees. None participated in data reading.

Andrea Aliverti received a consultation fee from L.I.F.E.

Acknowledgments

Authors contributions: PA and AA had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis, including and especially any adverse effects. AS, CV, SP, CL, AS, FN, MM, PA, and AA contributed substantially to the study design, data analysis and interpretation, and the writing of the manuscript. AL, DO, RR contributed substantially to study design, data interpretation, statistical analysis and writing of the

References (10)

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