9 Cough

When evaluating patients with a cough, the physician should remember that:

The complaint of cough should be taken seriously, because it is one of the few ways by which abnormalities of the respiratory tree manifest themselves. Cough can be divided into three categories:

Cough can be initiated by irritation of upper or lower airways. The most common causes of an acute cough are upper and lower respiratory infections (most often viral upper respiratory tract infection), asthma, bronchitis, laryngitis, and allergies (often seasonal), pneumonia, exacerbation of chronic obstructive pulmonary disease (COPD), and heart failure.

Common causes of a subacute cough include postinfection state and cough-variant asthma.

The most common causes of a chronic cough (duration more than 8 weeks) are chronic bronchitis, postnasal drip (PND; currently called “upper airway cough syndrome”) asthma, gastroesophageal reflux, and medications such as angiotensin-converting enzyme (ACE) inhibitors. In many instances, chronic cough has multiple causes. Other common causes are COPD, heart failure, tuberculosis, lung tumor, and habit (Table 9-1).

TABLE 9-1 Causes of Chronic or Persistent Cough


Respiratory Tract Problems


Adapted from Ritz HJ: Pinning down the cause of a chronic cough. JAAPA 17:27-38, 2004; with permission from Haymarket Media, Inc. and American Academy of Physician Assistants.

The most common causes of recurrent cough in children are recurrent viral upper respiratory tract infections, reactive airway disease, asthma, viral bronchitis, and allergies.

Nature of Patient

Viral infections represent the most common cause of acute cough at all ages. This is particularly true of preschool children and even more likely if they are in close daily contact with many other children. In school-age children, mycoplasmal pneumonias are quite common. Because the incubation period is long (approximately 21 days), infection spreads slowly. Bacterial pneumonias also cause coughing and have their highest incidence in winter months. Recurrent viral bronchitis is most prevalent in preschool and young school-age children and is the most common cause of a persistent cough in children of all ages. There may be a genetically determined host susceptibility to frequently recurring bronchitis. Young patients with recurrent cough are often asthmatic. Physicians should be suspicious of underlying asthma contributing to a recurrent cough when there is a family history of allergies, atopy, or asthma.

A chronic cough in children (Table 9-2) is frequently caused by allergic rhinitis, chronic sinusitis, or enlarged adenoids. A chronic cough in children during the winter months is often due to bronchitis from dry air. Although it is rare, chronic cough in very young children (younger than age 12 months) should suggest congenital malformations or neonatal infections, including viral and chlamydial pneumonias. Other relatively uncommon causes of chronic cough in young infants include recurrent aspiration of milk, saliva, or gastric contents and cystic fibrosis. A chronic cough in children between ages 1 and 5 years should suggest bronchiectasis or cystic fibrosis after the more common causes have been ruled out. In both children and adults, chronic cough may be the only manifestation of gastroesophageal reflux.

TABLE 9-2 Causes of Chronic Cough in Children According to Age

Infancy (age <1 yr)

Preschool (1 to 5 yr)


Common to all age groups

Modified from Padiman R: The child with persistent cough. Del Med J 73:149-156, 2000.

Chronic cough in adults most often is caused by chronic bronchitis (especially in smokers), gastroesophageal reflux disease (GERD), postnasal drip, asthma, environmental irritants, allergies, and habit. Chronic cough resulted from GERD, postnasal drip, or asthma in 99% of nonsmokers with a normal chest radiograph in one study. In older adults, any chronic cough without an obvious explanation should suggest tumor or tuberculosis.

Nature of Symptoms

When the cough is of sudden onset and associated with fever or symptoms of an acute infection, a viral cause is most likely. The cough is noisy, produces minimal sputum, and is often worse at night. With bacterial and mycoplasmal infections, cough is often the most prominent symptom. Its onset may occur over hours or days, and the sputum produced is usually thick and yellowish. In mycoplasmal infections, the cough may be severe and persist for 1 to 4 months, although all other signs and symptoms abate within 7 to 10 days.

The cough caused by a viral upper respiratory infection (URI) or viral bronchitis usually lasts for 7 to 10 days. If the cough persists for longer than 14 days, a secondary bacterial infection may exist. If the cough is associated with shortness of breath and bilateral wheezing, asthma is likely. The cough of asthma is usually nonproductive or productive of minimal clear mucoid secretions. An asthmatic cough is often worse in the late afternoon and at night; is associated with wheezing; is brought on by specific irritants; and is more common in patients with a family history of asthma, allergies, or atopy.

Patients with an acute or chronic cough secondary to upper airway cough syndrome (previously called postnasal drip) may not be aware of this condition. They should be questioned about swallowing mucus, frequent throat clearing, hawking, or cough that is worse in the morning. Examination may reveal mucoid secretions in the posterior pharynx, a cobblestone appearance of the mucosa, or signs of sinusitis. Although PND is usually caused by sinusitis, it may be caused by vasomotor or allergic rhinitis or nonallergic rhinitis with eosinophilia syndrome (NARES). It is important to differentiate these variant causes of rhinitis for effective treatment (Table 9-3).

Mar 21, 2018 | Posted by in BIOCHEMISTRY | Comments Off on Cough
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