A Wearable Multimodal Sensing System for Tracking Changes in Pulmonary Fluid Status, Lung Sounds, and Respiratory Markers.

Jesus Antonio Sanchez-Perez,Gari D Clifford,Brandi N Nevius,Goktug C Ozmen,Venu G Ganti,John A Berkebile,Omer T Inan,David W Wright,Samer A Mabrouk,Rishikesan Kamaleswaran,Christopher J Nichols

doi:10.3390/s22031130

Abstract

Heart failure (HF) exacerbations, characterized by pulmonary congestion and breathlessness, require frequent hospitalizations, often resulting in poor outcomes. Current methods for tracking lung fluid and respiratory distress are unable to produce continuous, holistic measures of cardiopulmonary health. We present a multimodal sensing system that captures bioimpedance spectroscopy (BIS), multi-channel lung sounds from four contact microphones, multi-frequency impedance pneumography (IP), temperature, and kinematics to track changes in cardiopulmonary status. We first validated the system on healthy subjects (n = 10) and then conducted a feasibility study on patients (n = 14) with HF in clinical settings. Three measurements were taken throughout the course of hospitalization, and parameters relevant to lung fluid status—the ratio of the resistances at 5 kHz to those at 150 kHz (K)—and respiratory timings (e.g., respiratory rate) were extracted. We found a statistically significant increase in K (p < 0.05) from admission to discharge and observed respiratory timings in physiologically plausible ranges. The IP-derived respiratory signals and lung sounds were sensitive enough to detect abnormal respiratory patterns (Cheyne–Stokes) and inspiratory crackles from patient recordings, respectively. We demonstrated that the proposed system is suitable for detecting changes in pulmonary fluid status and capturing high-quality respiratory signals and lung sounds in a clinical setting.

Highlights

Heart failure (HF), which affects over 6 million Americans, imposes a significant burden on patients and healthcare systems due to the more than 1 million hospitalizations per year [1]
We present a novel wearable multimodal sensing system for capturing simultaneous lung sounds from four sites on the anterior and posterior sides of the chest, impedance pneumography (IP)-derived respiratory waveforms, and bioimpedance spectroscopy (BIS)-based fluid measurements to assess cardiopulmonary health status, with concurrent kinematic and temperature data
The validation of the IP signals acquired with our system as respiratory surrogates was demonstrated in previous work [16], where we found that these IP-derived respiratory signals are highly correlated to tidal volume (TV) and can accurately estimate respiratory timings

Summary

Introduction

Heart failure (HF), which affects over 6 million Americans, imposes a significant burden on patients and healthcare systems due to the more than 1 million hospitalizations per year [1]. Acute decompensated HF, typified by the presence of pulmonary edema, dyspnea, and abnormal lung sounds [2], frequently results in hospitalizations that are associated with increased mortality [3]. Existing techniques for evaluating cardiopulmonary status usually consist of singlepoint measurements, such as manual lung auscultation or radiographic imaging, which only supply qualitative metrics regarding a patient’s health [5,6]. The absence of practical methods for tracking pulmonary edema and extracting respiratory waveforms, typically measured with obtrusive spirometers or face masks [7], likewise presents a considerable challenge for quantifying respiratory deterioration. A multimodal system that monitors fluid status through bioimpedance spectroscopy (BIS), lung acoustics via multi-location digital auscultation, and respiratory activity using multifrequency impedance pneumography (IP) could enable comprehensive tracking of cardiopulmonary function

Methods

Results

Conclusion