Chronic Cough? Sleep apnea evaluation is probably indicated according to new article in Journal Cough.

A new article in the Journal Cough suggests that patients with chronic cough should be evaluated for obstructive sleep apnea (OSA). The article "Chronic cough and obstructive sleep apnea in a community-based pulmonary practice." details evaluation of 75 chronic cough patients. 38 of these patients were evaluated for OSA and 33 were positve for OSA. That translates into 44% of all patients had OSA. That also translates into over 86% of patients with a chronic cough were positive for sleep apnea. The authors also reported "93% of the patients that had interventions to optimize their sleep-disordered breathing had improvement in their cough" which is an incredible relief. This is especially true since CPAP causes cough in some patients. The patients who did not get relief from CPAP should be evaluated on an oral appliance. Oral Appliances are better tolerated than CPAP by the majority of patients with obstructive sleep apnea.

The article Quantifying chronic cough: objective versus subjective measurements." from Respirology. 2010 Nov 5 discusses counting coughs and this approach could be used in patients to see if there is a circadian pattern to the coughs in apnea vs non-apnea patients. The authors stated "Cough counting correlates well with subjective assessment of cough and cough reflex sensitivity" .

A major fault of the authors, Sundar KM, Daly SE, Pearce MJ, Alward WT was that they did not go back and evaluate the other 37 patients for sleep apnea. I assume that the other patients were not "typical" sleep apnea patients but many patients with sleep apnea do not fit the typical pattern of obese, thick neck and older male patient. If the 86% OSA figure was consistent throughout the Chronic cough population than perhaps chronic cough would be an absolute indication for sleep apnea testing.

Another interesting correlation would be to GERD (gastroesophageal reflux) and OSA which is a known risk factor for GERD. GERD accounted for 37% of cough population as a single etiology but GERD was also involved in multiple etiologies cough in 31 of the 75 patients. Multiple etiologies for the chronic cough included: GERD-upper airway cough syndrome (UACS), 31%, GERD-cough variant asthma (CVA), 5%, and GERD-UACS-CVA 3%

There is a commonality between cough, breathing, TMJ disorders and oral and pharyngeal reflexes. These reflexes that control breathing and pharyngeal structures are well described by A J Miller in "ORAL AND PHARYNGEAL REFLEXES IN THE MAMMALIAN NERVOUS SYSTEM: THEIR DIVERSE RANGE IN COMPLEXITY AND THE PIVOTAL ROLE OF THE TONGUE"

I have frequent references to his work in the www.ihateheadaches.org site and the www.ihatecpap.com site. These reflexes have direct effects on swallowing and breathing two essential functions of the jaws, tongue and oral cavity. Chronic misuse of these structures leads to repetitive strain injuries to the muscles and joints. These are frequently lumped into a junk diagnosis of TMJ, TMD, MPD, myofascial pain, Myofacial pain and are associated with sleep disorders, chronic pain, fibromyalgia and other central sensitization disorders involving the trigeminal nerve.

Cough. 2010 Apr 15;6(1):2.
Chronic cough and obstructive sleep apnea in a community-based pulmonary practice.
Sundar KM, Daly SE, Pearce MJ, Alward WT.

Intermountain Utah Valley Pulmonary Clinic, 1055N, 300W, Provo, UT 84604, USA. krishna.sundar@imail.org
Abstract
BACKGROUND: Recent reports suggest an association between unexplained chronic cough and obstructive sleep apnea (OSA). Current guidelines provide an empiric integrative approach to the management of chronic cough, particularly for etiologies of gastroesophageal reflux (GERD), upper airway cough syndrome (UACS) and cough variant asthma (CVA) but do not provide any recommendations regarding testing for OSA. This study was done to evaluate the prevalence of OSA in patients referred for chronic cough and examine the impact of treating OSA in resolution of chronic cough.

METHODS: A retrospective review of chronic cough patients seen over a four-year period in a community-based pulmonary practice was done. Patients with abnormal chest radiographs, abnormal pulmonary function tests, history of known parenchymal lung disease, and inadequate followup were excluded. Clinical data, treatments provided and degree of resolution of cough was evaluated based on chart review. Specifically, diagnostic testing for OSA and impact of management of OSA on chronic cough was assessed.

RESULTS: 75 patients with isolated chronic cough were identified. 44/75 had single etiologies for cough (GERD 37%, UACS 12%, CVA 8%). 31/75 had multiple etiologies for their chronic cough (GERD-UACS 31%, GERD-CVA 5%, UACS-CVA 3%, GERD-UACS-CVA 3%). 31% patients underwent further diagnostic testing to evaluate for UACS, GERD and CVA. Specific testing for OSA was carried out in 38/75 (51%) patients and 33/75 (44%) were found to have obstructive sleep apnea. 93% of the patients that had interventions to optimize their sleep-disordered breathing had improvement in their cough.

CONCLUSIONS: OSA is a common finding in patients with chronic cough, even when another cause of cough has been identified. CPAP therapy in combination with other specific therapy for cough leads to a reduction in cough severity. Sleep apnea evaluation and therapy needs to considered early during the management of chronic cough and as a part of the diagnostic workup for chronic cough.

PMID: 20398333 [PubMed]PMCID: PMC2861010Free PMC Article

Respirology. 2010 Nov 5. doi: 10.1111/j.1440-1843.2010.01893.x. [Epub ahead of print]
Quantifying chronic cough: objective versus subjective measurements.
Faruqi S, Thompson R, Wright C, Sheedy W, Morice AH.

Division of Cardiovascular and Respiratory Studies, Hull York Medical School, University of Hull, Castle Hill Hospital, Cottingham, United Kingdom. HU16 5JQ.
Abstract
Background and objective: The assessment of chronic cough has been improved by the development of objective ambulatory cough monitoring systems and subjective quality of life questionnaires. Experimental induction of cough is a useful tool in the assessment of the cough reflex. We wanted to assess the reproducibility of and association between these measurements. Methods: This was a prospective observational study in patients with chronic cough of greater than six months duration. All patients had an initial 24 hour cough recording. They also completed a Leicester Cough Questionnaire, a Symptom Assessment Score, a Visual Analogue Score for cough and had a capsaicin cough challenge performed. They were reviewed at 8 weeks when all assessments were repeated. Results: The study included 25 patients (15 females) with a mean age of 54 years. The median cough count at the second visit (302) was significantly lower compared to the first visit (381, p<0.01). However the cough counts at both the visits correlated well (r=0.9. p<0.01).All the other forms of assessment were found to be highly reproducible at 8 weeks (r= 0.6-0.9, p<0.01). Cough counts correlated well with the other forms of assessment (r= 0.4-0.6, p<0.01). There was good correlation between each of the subjective forms of assessment (r= 0.6, p<0.01). Conclusions: The various forms of assessment of cough are reproducible. Cough counting correlates well with subjective assessment of cough and cough reflex sensitivity. It appears to lie between these latter two assessments of cough and may represent the best global objective synthesis of cough.

© 2010 The Authors. Respirology © 2010 Asian Pacific Society of Respirology.
PMID: 21054670 [PubMed - as supplied by publisher]