Evaluation of an ambulatory system for the quantification of cough frequency in patients with chronic obstructive pulmonary disease

Abstract

BackgroundTo date, methods used to assess cough have been primarily subjective, and only broadly reflect the impact of chronic cough and/or chronic cough therapies on quality of life. Objective assessment of cough has been attempted, but early techniques were neither ambulatory nor feasible for long-term data collection. We evaluated a novel ambulatory cardio-respiratory monitoring system with an integrated unidirectional, contact microphone, and report here the results from a study of patients with COPD who were videotaped in a quasi-controlled environment for 24 continuous hours while wearing the ambulatory system.MethodsEight patients with a documented history of COPD with ten or more years of smoking (6 women; age 57.4 ± 11.8 yrs.; percent predicted FEV1 49.6 ± 13.7%) who complained of cough were evaluated in a clinical research unit equipped with video and sound recording capabilities. All patients wore the LifeShirt® system (LS) while undergoing simultaneous video (with sound) surveillance. Video data were visually inspected and annotated to indicate all cough events. Raw physiologic data records were visually inspected by technicians who remained blinded to the video data. Cough events from LS were analyzed quantitatively with a specialized software algorithm to identify cough. The output of the software algorithm was compared to video records on a per event basis in order to determine the validity of the LS system to detect cough in COPD patients.ResultsVideo surveillance identified a total of 3,645 coughs, while LS identified 3,363 coughs during the same period. The median cough rate per patient was 21.3 coughs·hr-1 (Range: 10.1 cghs·hr-1 – 59.9 cghs·hr-1). The overall accuracy of the LS system was 99.0%. Overall sensitivity and specificity of LS, when compared to video surveillance, were 0.781 and 0.996, respectively, while positive- and negative-predictive values were 0.846 and 0.994. There was very good agreement between the LS system and video (kappa = 0.807).ConclusionThe LS system demonstrated a high level of accuracy and agreement when compared to video surveillance for the measurement of cough in patients with COPD.

Comparison of Nocturnal Cough Analysis in Healthy Subjects and in Patients with Cystic Fibrosis and Primary Ciliary Dyskinesia: A Prospective Observational Study

“…Different cough count devices are available: simple free-standing digital audio recorders [1, 14, 29], devices that combine electromyography and a microphone [2, 15], or a combination of motion transducers in a vest and a throat microphone [30]. In these devices, either automatic cough detection is not available or the software has not been validated in CF and PCD patients [31]. The software version we used during the study did not reliably score the total number of coughs, and we had to manually mark cough sounds.…”

Validated Methods of Cough Assessment: A Systematic Review of the Literature

“…Ten of them were validation studies concerning cough frequency monitoring in children and/or adults [12,13,14,15,16,17,18,19,20,21]. Seven studies validating cough-specific quality-of-life scores were included [22,23,24,25,26,27,28,29].…”

“…Measurement units are the explosive sound each time the patient coughs [13,15,21,32] or the coughing episode [18] occurs, and the events are defined as separate from one another by a free interval of a determined duration. Cough frequency can also be expressed in units of time spent coughing (e.g.…”

“…Four types of technology have been developed to identify coughs and to measure cough frequency. The first type of device is based on audio-recognition alone [7,13,15]; the second type of technology is based on audio signals plus electromyography (EMG; by identifying intercostal and/or abdominal muscle contractions, a cough is identified when the audio and EMG signals occur simultaneously) [17,18]; the third type is based on an accelerometer which measures the vibration at the suprasternal notch alone [16], and the fourth type is a multiparametric device based on plethysmography, electrocardiography, and an accelerometer (LifeShirt; VivoMetrics) [21]. All of these can potentially be used in an ambulatory setting.…”

Targeting TRP channels for chronic cough: from bench to bedside

“…There are currently several systems in use, but none are commercially available at present; the LifeShirt (VivoMetrics Incorporate, Ventura, CA) (Coyle et al 2005;Smith 2010) and the CoughCOUNT (KarmelSonix, Haifa, Israel) (Vizel et al 2010) are no longer in production. The other systems in use include the Leicester Cough Monitor, which, although widely published, is not yet fully automated ) (McGuinness et al 2008.…”