Establishing a gold standard for manual cough counting: video versus digital audio recordings

BACKGROUND: Manual cough counting is time-consuming and laborious; however it is the standard to which automated cough monitoring devices must be compared. We have compared manual cough counting from video recordings with manual cough counting from digital audio recordings. METHODS: We studied 8 patients with chronic cough, overnight in laboratory conditions (diagnoses were 5 asthma, 1 rhinitis, 1 gastro-oesophageal reflux disease and 1 idiopathic cough). Coughs were recorded simultaneously using a video camera with infrared lighting and digital sound recording. The numbers of coughs in each 8 hour recording were counted manually, by a trained observer, in real time from the video recordings and using audio-editing software from the digital sound recordings. RESULTS: The median cough frequency was 17.8 (IQR 5.9–28.7) cough sounds per hour in the video recordings and 17.7 (6.0–29.4) coughs per hour in the digital sound recordings. There was excellent agreement between the video and digital audio cough rates; mean difference of -0.3 coughs per hour (SD ± 0.6), 95% limits of agreement -1.5 to +0.9 coughs per hour. Video recordings had poorer sound quality even in controlled conditions and can only be analysed in real time (8 hours per recording). Digital sound recordings required 2–4 hours of analysis per recording. CONCLUSION: Manual counting of cough sounds from digital audio recordings has excellent agreement with simultaneous video recordings in laboratory conditions. We suggest that ambulatory digital audio recording is therefore ideal for validating future cough monitoring devices, as this as this can be performed in the patients own environment

Objective cough frequency in Idiopathic Pulmonary Fibrosis

Background: Cough is a common presenting symptom in patients with Idiopathic Pulmonary Fibrosis (IPF). This study measured cough rates in IPF patients and investigated the association between cough and measures of health related quality of life and subjective cough assessments. In addition, IPF cough rates were related to measures of physiological disease severity and compared to cough rates in health and other respiratory conditions.Methods: Nineteen IPF patients, mean age 70.8 years ± 8.6, five female (26.3%) were studied. Subjects performed full pulmonary function testing, 24 hour ambulatory cough recordings, completed a cough related quality of life questionnaire (Leicester Cough Questionnaire) and subjectively scored cough severity with a visual analogue scale. Ambulatory cough recordings were manually counted and reported as number of coughs per hour.Results: The 24hr cough rates were high (median 9.4, range 1.5-39.4), with day time rates much higher than night time (median 14.6, range 1.9-56.6 compared to 1.9, range 0-19.2, p = 0.003). Strong correlations were found between objective cough frequency and both the VAS (day r = 0.80, p &lt; 0.001, night r = 0.71, p = 0.001) and LCQ (r = -0.80, p &lt; 0.001), but not with measures of pulmonary function. Cough rates in IPF were higher than healthy subjects (p &lt; 0.001) and asthma patients (p &lt; 0.001) but similar to patients with chronic cough (p = 0.33).Conclusions: This study confirms objectively that cough is a major, very distressing and disabling symptom in IPF patients. The strong correlations between objective cough counts and cough related quality of life measures suggest that in IPF patient's, perception of cough frequency is very accurate.</p

Use of zonal distribution of lung crackles during inspiration and expiration to assess disease severity in idiopathic pulmonary fibrosis

Purpose of the study To measure the number and distribution of crackles in patients with idiopathic pulmonary fibrosis (IPF) and assess how this relates to measures of disease severity. Study design Fourteen patients with IPF had both the number of crackles per litre of lung volume and lung function measured every 3 months for 1 year. Crackle counts were expressed according to position (upper and lower zones) and whether they occurred during inspiration and expiration. Results At baseline, crackle count per unit volume was higher at the bases than the apices and higher during inspiration than during expiration. There was a significant relationship between lung function and number of crackles per unit volume. Upper zone crackles during inspiration (crackle count vs forced vital capacity (FVC): r=0.69, p=0.007) and lower zone crackles during expiration (crackle count vs FVC: r=0.55, p=0.04) demonstrated the strongest relationship with lung function. Conclusions Number and distribution of crackles in IPF relate to physiological measures of disease severity. Inspiratory lower zone crackles were universal and extensive but the presence, hence, development of inspiratory upper zone crackles and expiratory lower zone crackles correlated with measures of poorer lung function. The presence or appearance of these assessed using chest auscultation provides a clinician with simple measure of disease severity, and possibly progression, prompting further physiological assessment and review of treatment.</p

The description of cough sounds by healthcare professionals

BACKGROUND: Little is known of the language healthcare professionals use to describe cough sounds. We aimed to examine how they describe cough sounds and to assess whether these descriptions suggested they appreciate the basic sound qualities (as assessed by acoustic analysis) and the underlying diagnosis of the patient coughing. METHODS: 53 health professionals from two large respiratory tertiary referral centres were recruited; 22 doctors and 31 staff from professions allied to medicine. Participants listened to 9 sequences of spontaneous cough sounds from common respiratory diseases. For each cough they selected patient gender, the most appropriate descriptors and a diagnosis. Cluster analysis was performed to assess which cough sounds attracted similar descriptions. RESULTS: Gender was correctly identified in 93% of cases. The presence or absence of mucus was correct in 76.1% and wheeze in 39.3% of cases. However, identifying clinical diagnosis from cough was poor at 34.0%. Cluster analysis showed coughs with the same acoustics properties rather than the same diagnoses attracted the same descriptions. CONCLUSION: These results suggest that healthcare professionals can recognise some of the qualities of cough sounds but are poor at making diagnoses from them. It remains to be seen whether in the future cough sound acoustics will provide useful clinical information and whether their study will lead to the development of useful new outcome measures in cough monitoring