Chronic cough

This is what my son has. He has a combination of Post Nasal Drip and Asthma which falls under the United Airway Disease to add another level of complication. The most important and troubling aspect of this disease is this statement from the article “Often, a careful history and physical examination can suggest, but are not sufficient to diagnose, the cause of chronic cough. For example, classic findings on history and physical examination associated with PNDS, asthma, and GERD can be unreliable because there are silent forms of these diseases.11-13” Click here or on the pdf file to learn more or read an excerpt below.

 

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CONCLUSION The most common causes of chronic cough are PNDS, asthma, GERD, or some combination of these. A systematic approach to diagnosis and treatment is effective for most cases of chronic cough.

Chronic cough can cause complications in respiratory, cardiovascular, central nervous system, gastrointestinal, genitourinary, and musculoskeletal systems. Hence, chronic cough is a multisystemic health concern for many patients seen by family physicians. This paper focuses on management of the most common causes of chronic cough in adults: postnasal drip syndrome (PNDS), asthma, and gastroesophageal reflux disease (GERD).

Quality of evidence MEDLINE was searched for articles related to diagnosis and treatment of chronic cough, using the key words chronic cough, postnasal drip syndrome, asthma, cough variant asthma, and gastroesophageal reflux disease. The search was limited to human investigations completed between 1970 and 2000, written in English and conducted on both sexes. Bibliographies from these articles were screened for additional references. A total of 33 articles were used in this review; most were cohort and case studies and review articles. Few randomized control studies were found.

Importance of chronic cough Cough, an important respiratory defense mechanism, is responsible for clearing excessive secretions, fluids, or foreign material from the airway.2,8 Despite its protective role, excessive coughing can cause multisystem problems. Common complications, such as anxiety, fatigue, insomnia, myalgia, dysphonia, perspiring, and urinary incontinence,2,9 often force patients to seek medical help. Other difficulties, including heightened self-consciousness and changes in lifestyle, are also frequent consequences of chronic cough.10 The severe effects on health and the possibility of more serious causes of cough warrant spending time to arrive at an accurate diagnosis and treatment plan.

Differential diagnosis Chronic cough can have many causes (Table 1). Almost all chronic coughs, however, can be attributed to PNDS, asthma, GERD, or some combination of these in immunocompetent, non-smoking patients who have normal results of chest radiographs and do not take angiotensin- converting enzyme (ACE) inhibitors.2 These three common clinical conditions should be considered first during diagnostic evaluation. Often, a careful history and physical examination can suggest, but are not sufficient to diagnose, the cause of chronic cough. For example, classic findings on history and physical examination associated with PNDS, asthma, and GERD can be unreliable because there are silent forms of these diseases.11-13 The features and timing of chronic cough are also of little diagnostic value.14 Additional investigations and responses to trials of empiric therapy based on the most likely etiology are essential (Figure 1).

Initial investigations should include a chest radiograph, which can detect many of the more ominous diseases mentioned in Table 1. Evidence of these diseases should prompt appropriate referral and treatment. When results of chest radiographs are normal or unchanged from those of radiographs taken for previous unrelated diseases in immunocompetent patients, PNDS, asthma, GERD, or some combination of these is highly probable.2 Additional investigations, including a methacholine challenge test, sinus radiography, and an esophageal pH probe, might be necessary.

Often, a positive response to empiric therapy for a suspected cause of chronic cough is essential for confirming its diagnosis. Optimizing therapy by adding treatments for concomitant causes of chronic cough might be required for some patients. Repeated failure of therapy or combination therapy should prompt referral to an appropriate specialist.

Postnasal drip syndrome

Postnasal drip syndrome is the most common cause of chronic cough. It most often occurs after viral upper respiratory tract infections, such as those caused by respiratory syncytial or parainfluenza viruses and sometimes by Chlamydia pneumoniae (TWAR strain), Mycoplasma pneumoniae, or Bordetella pertussis. 2,15 Other causes of PNDS include perennial rhinitis; rhinitis as a consequence of seasonal allergens, irritants, drugs, and vasomotor responses; and chronic sinusitis.2 Whatever the cause, chronic inflammation augments nasal and sinus secretions that continuously stimulate the cough reflex.

Diagnosis of PNDS is based on a combination of historic, physical, and radiologic findings, and responses to treatment. The most common complaint of those with PNDS is a sensation of tickling or a constant drip in the back of the throat.2 Throat clearing, nasal congestion, rhinorrhea, and hoarseness are other symptoms of PNDS; some of those with PNDS have no symptoms.3 Exacerbation of symptoms after exposure to allergens, irritants, or drugs suggests rhinitis as the cause of PNDS. Onset of watery rhinorrhea with changes in temperature implies vasomotor rhinitis. Radiographs of sinuses showing air-fluid levels, opacifications, or mucosal thickening (> 6 mm) are diagnostic of chronic sinusitus.2

A positive response to therapy is essential for determining that PNDS is the cause of chronic cough. Treatment for postinfectious, perennial, and vasomotor rhinitis includes a first-generation antihistamine, such as dexbrompheniramine, in combination with a pseudoephedrine decongestant.11,16,17 The cough, if caused by PNDS, usually improves within a few days to 2 weeks after therapy begins. Poor improvement suggests that an inappropriate antihistamine was used or that there are other concomitant causes of chronic cough. The efficacy of first-generation antihistamines in treating PNDS is attributed to their anticholinergic properties, which make them effective against nonhistaminemediated causes of PNDS. Insomnia, anxiety, tachycardia, palpitations, hypertension, diminished micturition, increased intraocular pressure, dr y eyes, and a dry mouth are all potential side effects. Ipratropium bromide is useful for treating perennial and vasomotor rhinitis.2,3

Managing allergic rhinitis should begin with allergen testing to identify environmental exposures and indicate exposures to be avoided. Newer nonsedating antihistamines, such as loratadine, are effective.3 Steroids, sodium cromoglycate, or intranasal antihistamines (eg, azelastine) are also successful treatments for allergic rhinitis.2

Treatment of chronic sinusitis includes a combination of antibiotic, anti-inflammatory, and decongestant therapy.2,3,11,16,17 A 3-week course of antibiotic therapy is needed to treat the most common microbes responsible for sinusitis (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus. In addition, dexbrompheniramine and pseudoephedrine should be used for 3 weeks, followed by nasal steroids, which can be used for up to 3 months. Surgery should be considered for recalcitrant chronic sinusitis.2

Asthma

Chronic cough is often caused by asthma. Its usual clinical manifestations include some combination of cough, wheezing, dyspnea, and chest tightness. In up to 57% of asthma cases, however, cough is the only presenting symptom18 (cough variant asthma). Given the high prevalence of asthma in patients of all ages, asthma should always be entertained as a cause of chronic cough.

Along with the symptoms noted above, airway hyperresponsiveness19 and reversible airflow obstruction20 can establish a diagnosis of asthma. Degree of obstruction is most accurately assessed by spirometry, which measures forced expiratory volume in 1 second (FEV1). In asthma patients, at least a 12% reversibility of baseline airflow obstruction occurs spontaneously or in response to therapy.20,21 Because reversible airflow obstruction is uncommon in patients with cough variant asthma, their airway hyperresponsiveness must be measured. A methacholine challenge test has a positive predictive value up to 88% and negative predictive value of 100%.2,3,11 While negative results of a methacholine test rule out cough variant asthma, positive results only suggest it. A definitive diagnosis can be made when the cough resolves after a trial of therapy.

Conventional asthma treatment reduces both airway hyperresponsiveness and chronic cough in most patients with cough variant asthma.2,3 Canadian consensus guidelines for asthma include use of β-agonists to relieve symptoms immediately and inhaled corticosteroids (with or without oral corticosteroids, depending on severity) to control inflammation.21 β-Agonists give patients only transitory relief from chronic cough.22 Most patients’ chronic coughs are relieved completely in 6 to 8 weeks2,3 with β-agonists plus either inhaled corticosteroids23 or a combination of inhaled and oral corticosteroids.24 Steroid therapy can be discontinued once the cough stops.2,3 Sometimes cough recurs, especially with exposure to precipitating respiratory irritants or allergens.

Editor’s key points

• Chronic cough, a common condition in adults, can present a diagnostic challenge, although family physicians can readily identify the usual causes.

• The most common causes are postnasal drip syndrome, asthma, and gastroesophageal reflux disease, or a combination of these.

• Chest x-ray examination should be done first to rule out more ominous causes of cough, followed by an empirical trial of therapy directed at the most likely cause based on history and examination. Improvement in the cough confirms the diagnosis.

Conclusion Chronic cough is a common complaint with an extensive differential diagnosis, although most cases are caused by PNDS, asthma, GERD, or some combination of these. Although cough is a protective respiratory clearance reflex, for many adults it is a severe and prolonged health complaint. A systematic approach to diagnosis of chronic cough can reduce much of its morbidity for most of those who suffer from it.

11. Pratter MR, Bartter T, Akers S, Dubois J. An algorithmic approach to chronic cough. Ann Intern Med 1993;119:977-83.

12. Irwin RS, French CL, Curley FJ, Zawacki JK, Bennett FM. Chronic cough due to gastroesophageal reflux: clinical, diagnostic and pathogenetic aspects. Chest 1993;104:1511-7.

13. Irwin RS, Corrao WM, Pratter MR. Chronic persistent cough in the adult: the spectrum and frequency of causes and successful outcome of specific therapy. Am Rev Respir Dis 1981;123:413-7

 

 

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