MANAGING COUGH AS A DEFENSE-MECHANISM AND AS A SYMPTOM - A CONSENSUS PANEL REPORT OF THE AMERICAN-COLLEGE-OF-CHEST-PHYSICIANS

1. Cough can (a) be an important defense mechanism to help clear exces sive secretions and foreign material from airways; (b) be an important factor in the spread of infection; (c) maintain consciousness during potentially lethal arrhythmias and/or convert arrhythmias to more norm al cardiac rhythms; and (d) present as one of the most common symptoms for which patients seek medical attention and spend health-care dolla rs. 2. Cough involves a complex reflex are that begins with the stimul ation of an irritant receptor. Most receptors are probably located in the respiratory system; the existence of a discrete central cough cent er has not been demonstrated. Evidence to date suggests that the cough center is diffusely located in the medulla. An effective cough depend s on the ability to achieve high gas flows and intrathoracic pressures , enhancing the removal of mucus adhering to the airway wall. Cough in effectiveness may occur when respiratory muscles are weakened or when the surface adhesive properties of mucus are altered. While a variety of nonpharmacologic protussive treatment modalities may improve cough mechanics, clinical studies documenting improvement in patient morbidi ty and mortality are lacking. 3. It is the complications of cough that lead patients to seek medical attention. The most common complication s are subjective perceptions of exhaustion and self-consciousness, and symptoms of insomnia, hoarseness, musculoskeletal pain: sweating, and urinary incontinence. The pressures produced during vigorous coughing can cause a variety of complications in nearly all organ systems. 4. The two categories of cough, are acute, lasting less than 3 weeks, and chronic, lasting 3 to 8 weeks or longer; they are not mutually exclus ive (Grade II-2, III-3). Acute cough is most frequently due to the com mon cold (Grade III). Chronic cough is often simultaneously due to mor e than one condition (Grade II-2, II-3), but can be the sole clinical manifestation of asthma and gastroesophageal reflux disease (GERD) (Gr ade II-2). The most common causes of chronic cough in nonsmokers are p ostnasal drip syndrome (PNDS), asthma, and/or GERD (Grade II-2, II-3), whether or not the cough is described as dry or productive (Grade II- 2). PNDS, asthma, and/or GERD are likely to be causes(s) of chronic co ugh approximately 100% of the time in nonsmokers who are not taking an giotensin-converting enzyme inhibitor (ACEI) drugs and who have normal or nearly normal chest radiographs showing no more than stable incons equential scars (Grade II-2). 5. PNDS, either singly or in combination with other conditions, is the single most common cause of chronic cou gh for which patients seek medical attention (Grade II-2). The symptom s and signs of PNDS are nonspecific (Grade II-2); therefore, a definit ive diagnosis of PNDS-induced cough cannot be made from history and ph ysical examination alone. A favorable response to specific therapy for PNDS, with resolution of cough, is a crucial step in confirming that PNDS is present and is the etiology of cough. The combination of a fir st-generation antihistamine and a decongestant is considered to be the most consistently effective sole form of therapy in treating most pat ients with PNDS-induced cough not due to sinusitis (Grade II-2). In mo st patients, some improvement in cough will be seen within 1 week of i nitiation of therapy. Newer generation, relatively nonsedating antihis tamines have been found ineffective in treating acute cough associated with the common cold (Grade I) and are not as effective as first-gene ration antihistamines in treating PNDS secondary to nonallergic condit ions. The first-generation antihistamines should be used preferentiall y to treat PNDS-induced cough that is nonhistamine-mediated (Grade I, II-2). 6. Asthma is a common cause of chronic cough. A diagnosis of co ugh-variant asthma is suggested by the presence of airway hyperrespons iveness, and confirmed only when the cough resolves with asthma medica tions. The treatment of cough-variant asthma is the same as for asthma presenting with other symptoms. Inhaled medications prescribed for as thma may worsen the cough. 7. GERD can cause cough by aspiration, but it most likely causes chronic cough in patients with normal radiograph s by a vagally mediated reflex mechanism (Grade II, II-2). When GERD i s the cause of chronic cough, GI symptoms are often absent (Grade II-2 ). Twenty-four-hour esophageal pH monitoring is the most sensitive and specific test For GERD. In interpreting the test, it is important to assess the duration and frequency of reflux episodes, and the temporal relationship between reflux and cough episodes. Patients with normal standard reflux parameters may still have reflux as a cause of cough i f a temporal relationship exists (Grade II-2). When 24-h esophageal pH monitoring cannot be done, an empiric trial of antireflux medication is appropriate when GERD is suspected as a cause of cough. However, if empiric treatment fails, GERD cannot be ruled out until objective stu dies are conducted (Grade III) because the empiric therapy may not hav e been intensive enough or medical therapy may have failed. Because mi nimum consistently effective therapy for GERD-induced chronic cough is not known, initial treatment should include diet and lifestyle change s in addition to drugs. Cough due to GERD has been reported to resolve with medical therapy in 70 to 100% of patients; mean time to recovery may take as long as 169 to 179 days (Grade II-2). Antireflux surgery may be considered after intensive medical therapy has been documented to have failed. 8. Cough is a principal feature of chronic bronchitis (CB) and its treatment should chiefly be directed to reduction of sput um production and airway inflammation (eg, by smoking cessation and re moval of environmental irritants) (Grade II-2). While CB is among tie most frequent causes of chronic cough in the community, it is the caus e in only about 5% in series of patients who Seek medical attention fo r cough. Ipratropium can decrease sputum production and cough (Grade I ). Nonspecific cough suppressants should be avoided, and mucolytics ar e of uncertain benefit. Although the effectiveness systemic corticoste roids and antibiotics on cough have not been specifically studied, the y are likely to be helpful in decreasing cough during exacerbations of COPD (Grade III). 9. Bronchiectasis is a cause of chronic cough in a relatively small number of patients: the diagnosis is establ