Cough

Key Features

Essentials of Diagnosis

• Inquire about

  • Age

  • Tobacco use, e-cigarette use, vaping, cannabis use

  • Occupational history

  • Environmental exposures

  • Risk for SARS-CoV-2 infection

  • Duration of cough; dyspnea (at rest or with exertion)

  • Vital signs (heart rate, respiratory rate, body temperature); pulse oximetry; chest examination

  • Chest radiography, especially when unexplained cough lasts more than 3–6 weeks

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)

• 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

• Signs of pneumonia

  • Tachycardia

  • Tachypnea

  • Fever

  • Rales

  • 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 heart failure (HF)

  • Symmetric basilar rales

  • Abnormal jugular venous pressure

  • Positive hepatojugular reflux

Acute cough

• Most due to viral respiratory tract infections

• 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

  • HF

  • Hay fever (allergic rhinitis)

  • Occupational factors

Persistent cough

• Usually due to

  • Angiotensin-converting enzyme (ACE) inhibitor therapy

  • Postnasal drip

  • Asthma

  • Gastroesophageal reflux disease (GERD)

• Less common causes

  • Bronchogenic carcinoma

  • Chronic bronchitis

  • Bronchiectasis

  • Other chronic lung disease

  • HF

Chronic cough

• May suggest Sjögren syndrome if accompanied by dry eyes

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

• If productive (especially with hemoptysis), consider tuberculosis

Differential Diagnosis

Acute cough

• Viral upper respiratory infection or postviral cough (most common)

• Infection with SARS-CoV-2

• Asthma

• Allergic rhinitis

• HF

• ACE inhibitor therapy

Persistent and ...