High-Resolution Time-Frequency Spectrum-Based Lung Function Test from a Smartphone Microphone

In this paper, a smartphone-based lung function test, developed to estimate lung function parameters using a high-resolution time-frequency spectrum from a smartphone built-in microphone is presented. A method of estimation of the forced expiratory volume in 1 s divided by forced vital capacity (FEV1/FVC) based on the variable frequency complex demodulation method (VFCDM) is first proposed. We evaluated our proposed method on 26 subjects, including 13 healthy subjects and 13 chronic obstructive pulmonary disease (COPD) patients, by comparing with the parameters clinically obtained from pulmonary function tests (PFTs). For the healthy subjects, we found that an absolute error (AE) and a root mean squared error (RMSE) of the FEV1/FVC ratio were 4.49% ± 3.38% and 5.54%, respectively. For the COPD patients, we found that AE and RMSE from COPD patients were 10.30% ± 10.59% and 14.48%, respectively. For both groups, we compared the results using the continuous wavelet transform (CWT) and short-time Fourier transform (STFT), and found that VFCDM was superior to CWT and STFT. Further, to estimate other parameters, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and peak expiratory flow (PEF), regression analysis was conducted to establish a linear transformation. However, the parameters FVC, FEV1, and PEF had correlation factor r values of 0.323, 0.275, and −0.257, respectively, while FEV1/FVC had an r value of 0.814. The results obtained suggest that only the FEV1/FVC ratio can be accurately estimated from a smartphone built-in microphone. The other parameters, including FVC, FEV1, and PEF, were subjective and dependent on the subject’s familiarization with the test and performance of forced exhalation toward the microphone.

[1]  C. Irvin,et al.  Knowledge and use of office spirometry for the detection of chronic obstructive pulmonary disease by primary care physicians. , 2005, Respiratory care.

[2]  Measurements on a little known sound source - the Vortex Whistle , 2016, 1604.02251.

[3]  J. Hankinson,et al.  General considerations for lung function testing , 2005, European Respiratory Journal.

[4]  T. Seemungal,et al.  Time course and recovery of exacerbations in patients with chronic obstructive pulmonary disease. , 2000, American journal of respiratory and critical care medicine.

[5]  M Terrin,et al.  Reference spirometric values using techniques and equipment that meet ATS recommendations. , 2015, The American review of respiratory disease.

[6]  T. Petty,et al.  Benefits of and barriers to the widespread use of spirometry , 2005, Current opinion in pulmonary medicine.

[7]  Gretchen A. Piatt,et al.  Patients with Complex Chronic Diseases: Perspectives on Supporting Self-Management , 2007, Journal of General Internal Medicine.

[8]  Kajiro Watanabe,et al.  Application of the Vortex Whistle to the Spirometer , 1999 .

[9]  H. S. Wolff,et al.  iRun: Horizontal and Vertical Shape of a Region-Based Graph Compression , 2022, Sensors.

[10]  Eric C. Larson,et al.  SpiroSmart: using a microphone to measure lung function on a mobile phone , 2012, UbiComp.

[11]  Phillips Yy,et al.  Standards for the diagnosis and care of patients with chronic obstructive pulmonary disease (COPD) and asthma. This official statement of the American Thoracic Society was adopted by the ATS Board of Directors, November 1986. , 1987, The American review of respiratory disease.

[12]  Eric C. Larson,et al.  SpiroCall: Measuring Lung Function over a Phone Call , 2016, CHI.

[13]  J Stocks,et al.  Using the lower limit of normal for the FEV1/FVC ratio reduces the misclassification of airway obstruction , 2008, Thorax.

[14]  O Geiran,et al.  Daily home spirometry facilitates early detection of rejection in single lung transplant recipients with emphysema. , 1993, The European respiratory journal.

[15]  A. Miller,et al.  Lung function testing: selection of reference values and interpretative strategies. , 1992, The American review of respiratory disease.

[16]  Kirk H. Shelley,et al.  A Novel Approach Using Time–Frequency Analysis of Pulse-Oximeter Data to Detect Progressive Hypovolemia in Spontaneously Breathing Healthy Subjects , 2011, IEEE Transactions on Biomedical Engineering.

[17]  R. Vlahos,et al.  What is the contribution of respiratory viruses and lung proteases to airway remodelling in asthma and chronic obstructive pulmonary disease? , 2005, Pulmonary Pharmacology & Therapeutics.

[18]  K. Nikander,et al.  Reproducibility of home spirometry in children with newly diagnosed asthma , 2000, Pediatric pulmonology.

[19]  R. Pierce,et al.  Spirometry: an essential clinical measurement. , 2005, Australian family physician.

[20]  J. Hankinson,et al.  Standardisation of spirometry , 2005, European Respiratory Journal.

[21]  B. Lindgren,et al.  Determination of reliability and validity in home monitoring data of pulmonary function tests following lung transplantation. , 1997, Research in nursing & health.

[22]  Ki H. Chon,et al.  Estimation of Respiratory Rate From Photoplethysmogram Data Using Time–Frequency Spectral Estimation , 2009, IEEE Transactions on Biomedical Engineering.

[23]  A. Buist,et al.  Office spirometry for lung health assessment in adults: A consensus statement from the National Lung Health Education Program. , 2000, Chest.

[24]  BTS guidelines for the management of chronic obstructive pulmonary disease. The COPD Guidelines Group of the Standards of Care Committee of the BTS. , 1997, Thorax.

[25]  J. Morris,et al.  Spirometric standards for healthy nonsmoking adults. , 2015, The American review of respiratory disease.

[26]  R O Crapo,et al.  Pulmonary-function testing. , 1994, The New England journal of medicine.

[27]  K. Chon,et al.  A High Resolution Approach to Estimating Time-Frequency Spectra and Their Amplitudes , 2006, Annals of Biomedical Engineering.

[28]  Elizabeth A. Wasilevich,et al.  Spirometry Use Among Pediatric Primary Care Physicians , 2010, Pediatrics.

[29]  Eric C. Larson,et al.  Pulmonary Monitoring Using Smartphones , 2017, Mobile Health - Sensors, Analytic Methods, and Applications.

[30]  J. Scott,et al.  The use of home spirometry in detecting acute lung rejection and infection following heart-lung transplantation. , 1990, Chest.

[31]  P. Auld,et al.  Pulmonary Function Testing in Children: Techniques and Standards. , 1971 .

[32]  W. MacNee,et al.  Standards for the diagnosis and treatment of patients with COPD: a summary of the ATS/ERS position paper , 2004, European Respiratory Journal.

[33]  Ki H. Chon,et al.  Atrial flutter and atrial tachycardia detection using Bayesian approach with high resolution time-frequency spectrum from ECG recordings , 2013, Biomed. Signal Process. Control..

[34]  M. Estenne,et al.  Internet-based home monitoring of pulmonary function after lung transplantation. , 2002, American journal of respiratory and critical care medicine.

[35]  J E Cotes,et al.  Lung volumes and forced ventilatory flows , 1993, European Respiratory Journal.