Cough

Key Features

Essentials of Diagnosis

• Inquire about

  • Age; tobacco, e-cigarette vaping, or cannabis use history; duration of cough

  • Occupational history and environmental and infection exposures

  • Dyspnea (at rest or with exertion)

  • Vital signs (temperature, respiratory rate, heart rate)

  • Chest examination findings

General Considerations

• Cough results from stimulation of mechanical or chemical afferent nerve receptors in the bronchial tree

• Cough illness syndromes are defined as acute (< 3 weeks), persistent (3–8 weeks), or chronic (> 8 weeks)

• Postinfectious cough lasting 3–8 weeks also called subacute cough to distinguish this distinct clinical entity from acute and chronic cough

• The prevalence of pertussis infection in adults with a cough lasting > 3 weeks is 20%, although exact prevalence is difficult to ascertain due to the limited sensitivity of diagnostic tests

Clinical Findings

Symptoms and Signs

• Timing and character of cough are not very useful in establishing cause

• However, cough-variant asthma should be considered in adults with prominent nocturnal cough, and persistent cough with phlegm increases the patient's likelihood of chronic obstructive pulmonary disease (COPD)

• Acute cough syndromes

  • Most due to viral respiratory tract infections (eg, influenza, SARS-CoV-2)

  • Presence of post-tussive emesis or inspiratory whoop in adults modestly increases the likelihood of pertussis, and absence of paroxysmal cough and the presence of fever decreases its likelihood

  • Less common causes include heart failure (HF), hay fever (allergic rhinitis), and occupational factors

• Search for additional features of infection such as fever, nasal congestion, and sore throat

• Dyspnea (at rest or with exertion) may reflect a more serious condition

• Persistent cough is usually due to

  • Angiotensin-converting enzyme (ACE) inhibitor therapy

  • Postnasal drip

  • Asthma

  • Gastroesophageal reflux disease (GERD)

• Less common causes of persistent cough

  • Bronchogenic carcinoma

  • Chronic bronchitis

  • Bronchiectasis

  • Other chronic lung disease

  • HF

• Chronic cough

  • Accompanied by dry eyes may suggest Sjögren syndrome

  • If dry, it may be the first symptom of idiopathic pulmonary fibrosis

• Signs of pneumonia

  • Tachycardia

  • Tachypnea

  • Fever

  • Crackles

  • Decreased breath sounds

  • Fremitus

  • Egophony

• Signs of acute bronchitis: wheezing and rhonchi

• Signs of chronic sinusitis: postnasal drip

• Signs of COPD

  • Abnormal match test (inability to blow out a match from 10 inches away)

  • Maximum laryngeal height < 4 cm (measured from the sternal notch to the cricoid cartilage at end expiration)

• Signs of HF

  • Symmetric basilar rales

  • Abnormal jugular venous pressure

  • Positive hepatojugular reflux

Differential Diagnosis

Acute cough

• Acute respiratory tract infection

• Asthma

• Allergic rhinitis

• HF

• ACE inhibitor therapy

Persistent cough

• Environmental exposures (cigarette smoke, air pollution)

• Occupational exposures

• Pertussis, SARS-CoV-2

• Postnasal drip

• Asthma (including cough-variant asthma)

• GERD

• COPD

• Chronic aspiration

• Bronchiectasis, eosinophilic bronchitis

• Tuberculosis or other chronic infection

• Interstitial lung disease

• Bronchogenic carcinoma

Diagnosis