Diurnal and seasonal variation of cough episodes in healthy young adults

Cough detection using a non-contact microphone: A nocturnal cough study

An automatic non-contact cough detector designed especially for night audio recordings that can distinguish coughs from snores and other sounds is presented. Two different classifiers were implemented and tested: a Gaussian Mixture Model (GMM) and a Deep Neural Network (DNN). The detected coughs were analyzed and compared in different sleep stages and in terms of severity of Obstructive Sleep Apnea (OSA), along with age, Body Mass Index (BMI), and gender. The database was composed of nocturnal audio signals from 89 subjects recorded during a polysomnography study. The DNN-based system outperformed the GMM-based system, at 99.8% accuracy, with a sensitivity and specificity of 86.1% and 99.9%, respectively (Positive Predictive Value (PPV) of 78.4%). Cough events were significantly more frequent during wakefulness than in the sleep stages (p < 0.0001) and were significantly less frequent during deep sleep than in other sleep stages (p < 0.0001). A positive correlation was found between BMI and the number of nocturnal coughs (R = 0.232, p < 0.05), and between the number of nocturnal coughs and OSA severity in men (R = 0.278, p < 0.05). This non-contact cough detection system may thus be implemented to track the progression of respiratory illnesses and test reactions to different medications even at night when a contact sensor is uncomfortable or infeasible.

Impact of capsaicin concentration evoking coughs on clinical variables in patients with asthma

BACKGROUND

Inhaled capsaicin (8-methyl-N-vanillyl-6-nonenamide) has been used to induce cough in a safe and dose-dependent manner. Chronic cough is associated with an increased sensitivity to inhaled capsaicin in patients with asthma. The aim of this study was to evaluate clinical impact of capsaicin provocation test for chronic cough, and to find relationship between capsaicin concentration producing coughs and clinical variables in patients with asthma. Methods: 385 patients with chronic cough [capsaicin provocation test (+, n = 152)] vs. [capsaicin provocation test (-, n = 233)] who has done with capsaicin provocation test recruited and evaluated by asthma diagnosis and clinical variables. Asthma diagnoses were based on the Global Initiative for Asthma guidelines. Results: Capsaicin positivity was more prevalent in patient with asthma diagnosis than in patients without asthma diagnosis (129/304 vs. 24/81, p = 0.037). Capsaicin positivity was more prevalent in female patients than in male patients (123/271 = 45.4% vs. 30/114 = 26.3%, p = 0.001). Capsaicin concentration producing coughs correlated with smoke amount (r = 0.126, p = 0.014). Capsaicin positivity was more prevalent in nonsmoker patients than in smoker patients (133/295 = 45.1% vs. 20/90 = 22.2%, p = 0.001). Capsaicin concentration producing coughs negatively correlated with methacholine PC20 (4 mg mL^-1, p = 0.037), (16 mg mL^-1, p = 0.069) and (20 mg mL^-1, p = 0.045). Capsaicin concentration producing coughs correlated with BMI (r = 0.120, p = 0.019). Capsaicin concentration producing coughs negatively correlated with FEV₁/FVC % pred. (r = -0.137, p = 0.007). There was no relationship between capsaicin concentration producing coughs and age, IgE, and atopy. Conclusions: Capsaicin test for asthma diagnosis should be considered for variable clinical factors. Key message Cough in asthmatic patients is not only common and troublesome but also predicts disease severity and poor prognosis. The capsaicin cough challenge test is a simple and reproducible provocation method for assessing cough susceptibility in patients with cough. Capsaicin test for asthma diagnosis should be considered for variable clinical factors.