Cough (Case 9)

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Chapter 15
Cough (Case 9)

Ranjit Nair MD and Sean M. Studer MD, MSc

Case: The patient is a 66-year-old man with a history of diet-controlled diabetes mellitus who works as a truck driver and has not seen a physician for more than 10 years. He presents to the emergency department from home in respiratory distress for the past 8 hours. He admits to having rhinorrhea for the past 2 weeks, a cough with rust-colored sputum for the past 3 days, and right-sided chest pain every time he takes a deep breath. He also reports some shaking chills and subjective fever. He has never been hospitalized and has no known drug allergies. He smokes cigarettes only when he is drinking alcohol on the weekends.

On physical exam, his vital signs are temperature of 102.1° F orally, pulse of 105 beats per minute (bpm), respiratory rate of 30 breaths per minute, and blood pressure of 135/80 mm Hg; pulse oximetry is 85% on room air and 96% on 4 L oxygen via nasal cannula. In general, he appears anxious. On lung exam, crackles are auscultated at the right base.

Differential Diagnosis


Acute bronchitis




Cystic fibrosis


Speaking Intelligently

Cough is one of the most common respiratory complaints. Acute cough can be a symptom of a potentially life-threatening illness (e.g., pneumonia or pulmonary embolism), although most episodes are of minor consequence. Chronic cough (i.e., persisting for more than 3 weeks) is much more common and is associated with conditions such as postnasal drip, asthma, gastroesophageal reflux, chronic bronchitis, and bronchiectasis. Medications, specifically angiotensin-converting enzyme (ACE) inhibitors, may also be associated with chronic cough. Lung cancer and aspiration are less common etiologies of chronic cough.


Clinical Thinking

• Duration may be an important clue as to etiology of cough.

• Acute cough occurs in those with upper and lower respiratory infections, inhalation of noxious gases or chemicals, and aspiration.

• Chronic cough (i.e., cough persisting for more than 3 weeks) is usually explained by a careful history and physical examination, followed by specific diagnostic tests.

• For a cough to be worrisome enough for the patient to undergo a thorough assessment, it should be present for at least 6 to 8 weeks, not just a residual effect from a preceding respiratory tract infection.


• Include associated symptoms of fever, chills, pleuritic chest pain, and dyspnea.

• If the cough is productive, the character of the sputum should be described, including whether or not blood is present.

• Medication history may detect current use of an ACE inhibitor.

• A history of cigarette smoking, including current use and pack-year history, should prompt counseling regarding smoking cessation.

• Risk factors for pulmonary tuberculosis should be sought.

• Multiple prior lung infections might suggest bronchiectasis.

• Cystic fibrosis should be considered in the right clinical setting.

Physical Examination

• Given the possibility that postnasal drip may trigger cough, a thorough examination of the nose, sinuses, pharynx, and larynx should be performed.

• Associated wheezing may suggest the diagnosis of asthma or obstructive lung disease, or perhaps congestive heart failure.

• In the patient with acute cough, dullness to percussion, increased tactile fremitus, and localized crackles are strongly suggestive of bacterial pneumonia.

Tests for Consideration

Sputum analysis (Gram stain, acid-fast bacillus [AFB] smears, cytology) and culture may suggest a specific etiology, although fiberoptic bronchoscopy may be required if the diagnosis remains elusive.


Blood cultures in patients in whom bacterial pneumonia is suspected


• Rapid testing of nasopharyngeal specimens for influenza A and B antigens in the appropriate clinical setting


Pulmonary function tests (PFTs) if airway obstruction is considered likely



→ Chest radiography is indicated, although a radiographic image rarely identifies the etiology.


→ CT imaging may be required, depending upon the likely etiology.


Clinical Entities Medical Knowledge


Pneumonia is an infection of the lung parenchyma, usually occurring after aspiration of upper airway resident flora or inhalation of aerosolized material. Bacterial pneumonia is a common cause of morbidity and mortality in older adults, especially in those with comorbidities such as diabetes or congestive heart failure. A yearly influenza vaccine is important for all patients. Immunization with the 23-valent pneumococcal polysaccharide vaccine is recommended for all patients over the age of 64 years and other adults with specific risk factors. The 13-valent pneumococcal conjugate vaccine has recently been FDA approved for use in adults 50 years of age and older. The most common pathogens associated with community-acquired bacterial pneumonia are Streptococcus pneumoniae, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, Haemophilus influenzae, and Moraxella catarrhalis.


The patient with community-acquired bacterial pneumonia typically has fever, rigors, pleuritic chest pain, and cough productive of purulent sputum. In patients with atypical pneumonia the fever may be low grade, and patients may have nonproductive cough and no chest pain. However, there is variation in the initial symptoms and signs such that these presentations cannot reliably distinguish the specific infectious cause of the pneumonia. On physical exam there may be signs of consolidation, which can include the presence of localized dullness to percussion, increased tactile fremitus, and crackles. Examples of these sounds can be heard at this website:


Chest radiographs (PA and lateral) reveal parenchymal opacities, which will establish the diagnosis in the appropriate clinical setting (i.e., leukocytosis, fever, sputum production). A CBC with differential may help determine if there is a bacterial infection, and specifically, a differential will indicate a “left shift,” or increased numbers of bands, which suggests that a bacterial etiology is likely. An ABG measurement may help determine the severity of hypoxemia and inpatient disposition (i.e., whether admission to the ICU is necessary).

Pathogen identification should be attempted before antimicrobial therapy is initiated; this is especially important whenever the result is likely to change the approach to management, especially in patients in whom drug-resistant pathogens are eventually isolated. Pretreatment blood cultures should be drawn. Sputum Gram stain and culture should be obtained in hospitalized patients, because sensitivities can help guide therapy and help tailor antibiotics toward a specific organism. Patients with severe community-acquired pneumonia should also have urinary antigen tests sent for L. pneumophila and S. pneumoniae, although the Legionella urinary antigen is positive only in cases caused by L. pneumophila

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