Obstructive sleep apnoea: a cause of chronic cough

Chronic cough is a common reason for presentation to both general practice and respiratory clinics. In up to 25% of cases, the cause remains unclear after extensive investigations. We report 4 patients presenting with an isolated chronic cough who were subsequently found to have obstructive sleep apnoea. The cough improved rapidly with nocturnal continuous positive airway pressure therapy. Further studies are required to investigate the prevalence of coexistence of these common conditions

An Overnight increase in CO₂ predicts mortality in sleep disordered breathing

Background and objective: Sleep disordered breathing (SDB) is highly prevalent but under-recognized. Evidence is accumulating for its role as a predictor of mortality independent of cardiovascular risk factors. The role of hypercapnia in SDB is not known systematically, and between 11 and 43% of patients with SDB develop chronic hypercapnia. Hypercapnia predicts mortality in other respiratory conditions. The role of hypercapnia in independently predicting mortality in patients with SDB after assessing for the presence of airways disease and obesity was investigated. Methods: The records of 396 consecutive patients were examined retrospectively. Univariate and multivariate analyses were performed using Cox proportional hazards regression to determine the association between gas exchange and polysomnography (PSG) variables and all-cause mortality, adjusted for potential confounders, including age, gender and presence of co-morbidity and airways disease. Results: The mean age of our patient population was 55 ± 15 years, and the mean body mass index (BMI) was 30.6 ± 6.2 kg/m². Out of the 322 patient population, 258 were men. After 10 years, 25% had died, following a maximum follow-up of 16.7 years. Mortality among patients with SDB was predicted by a difference between evening and morning PaCO₂ (ΔPaCO₂) of ≥7 mm Hg and evening hypoxaemia (PaO₂ < 65 mm Hg), independent of age and the presence of co-morbidity and airways disease. There was a significant correlation between minimum oxygen saturation (SpO₂) and ΔPaCO₂ ≥ 7 mm Hg (P = 0.002) and evening PaO₂ < 65 mm Hg (P < 0.001). Conclusions: An overnight increase in CO₂ and evening hypoxaemia are independent mortality predictors in SDB. A low minimum SpO₂ identifies patients in whom morning and evening arterial blood gases are beneficial.7 page(s

Decrease in cough frequency following CPAP in patient 2 assessed with the Leicester Cough Monitor (LCM)

<p><b>Copyright information:</b></p><p>Taken from "Obstructive sleep apnoea: a cause of chronic cough"</p><p>http://www.coughjournal.com/content/3/1/7</p><p>Cough (London, England) 2007;3():7-7.</p><p>Published online 2 Jul 2007</p><p>PMCID:PMC1920530.</p><p></p

Improvement in cough specific quality of life after (continuous positive airway pressure) CPAP therapy in patient 2

<p><b>Copyright information:</b></p><p>Taken from "Obstructive sleep apnoea: a cause of chronic cough"</p><p>http://www.coughjournal.com/content/3/1/7</p><p>Cough (London, England) 2007;3():7-7.</p><p>Published online 2 Jul 2007</p><p>PMCID:PMC1920530.</p><p></p> (a) Leicester Cough Questionnaire (LCQ) Domain scores. (Higher score = better quality of life: QOL) (b) LCQ total score. (Minimal important difference 1.3; higher score = better QOL)