Continuous Cough Monitoring Using Ambient Sound Recording During Convalescence from a COPD Exacerbation

Michael G Crooks,Yvette Hayman,Caroline E Wright,Albertus Den Brinker,James D Williamson,Alyn H Morice,Peter Hill,Andrew Innes

doi:10.1007/s00408-017-9996-2

Michael G Crooks, Yvette Hayman + Show 6 more

Open Access

https://doi.org/10.1007/s00408-017-9996-2

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Abstract

PurposeCough is common in chronic obstructive pulmonary disease (COPD) and is associated with frequent exacerbations and increased mortality. Cough increases during acute exacerbations (AE-COPD), representing a possible metric of clinical deterioration. Conventional cough monitors accurately report cough counts over short time periods. We describe a novel monitoring system which we used to record cough continuously for up to 45 days during AE-COPD convalescence.MethodsThis is a longitudinal, observational study of cough monitoring in AE-COPD patients discharged from a single teaching hospital. Ambient sound was recorded from two sites in the domestic environment and analysed using novel cough classifier software. For comparison, the validated hybrid HACC/LCM cough monitoring system was used on days 1, 5, 20 and 45. Patients were asked to record symptoms daily using diaries.ResultsCough monitoring data were available for 16 subjects with a total of 568 monitored days. Daily cough count fell significantly from mean ± SEM 272.7 ± 54.5 on day 1 to 110.9 ± 26.3 on day 9 (p < 0.01) before plateauing. The absolute cough count detected by the continuous monitoring system was significantly lower than detected by the hybrid HACC/LCM system but normalised counts strongly correlated (r = 0.88, p < 0.01) demonstrating an ability to detect trends. Objective cough count and subjective cough scores modestly correlated (r = 0.46).ConclusionsCough frequency declines significantly following AE-COPD and the reducing trend can be detected using continuous ambient sound recording and novel cough classifier software. Objective measurement of cough frequency has the potential to enhance our ability to monitor the clinical state in patients with COPD.

Highlights

Chronic obstructive pulmonary disease (COPD) is a common, progressive and debilitating respiratory disease and is estimated to become the third leading cause of death world wide by 2030
We have previously reported the ability of a hybrid cough monitoring system consisting of the hull automated cough counter (HACC) and Leicester Cough Monitor software (LCM) to detect a significant fall in cough frequency following AE-COPD when measured on days 1, 5, 20 and 45 [10]
Consecutive patients admitted to a single teaching hospital with an AE-COPD associated with increased cough and one more of breathlessness, increased sputum volume, or purulence were recruited to the study

Summary

Introduction

Chronic obstructive pulmonary disease (COPD) is a common, progressive and debilitating respiratory disease and is estimated to become the third leading cause of death world wide by 2030. Acute worsening of symptoms including shortness of breath and cough are termed acute exacerbations (AE-COPD). AE-COPD often precipitate hospital admission and are a source of significant morbidity and mortality [1]. Exacerbation prevention and amelioration is one of the primary aims of COPD treatment. Cough and sputum production are reported by between 60 and 80% of patients with COPD [2, 3], and chronic cough and mucus hypersecretion are associated with faster lung function decline, increased exacerbation rate and increased mortality in COPD. Cough is an important feature in COPD in terms of risk stratification and prognostication; the impact of this symptom is underappreciated by clinicians [4]. Patients report increased cough preceding an AE-COPD suggesting that

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