What is the approach to a patient with dyspnea and cough, considering potential underlying conditions such as chronic obstructive pulmonary disease (COPD) or asthma?

Approach to Dyspnea and Cough

In patients presenting with dyspnea and cough, begin with a chest radiograph and focused assessment for the three most common causes: upper airway cough syndrome (UACS), asthma, and gastroesophageal reflux disease (GERD), which account for the majority of cases and often coexist. 1

Initial Assessment and Risk Stratification

Immediate Priorities

• Obtain a chest radiograph in all patients with chronic dyspnea and cough as it provides diagnostic information in approximately one-third of cases and guides further testing 1
• Check for red flag features requiring urgent evaluation: hemoptysis, weight loss, night sweats, fever, history of cancer/tuberculosis/AIDS, respiratory distress, or vital sign abnormalities 2, 1
• Review medication list immediately - if the patient is taking an ACE inhibitor, discontinue it as this causes cough in a significant proportion of patients, with resolution typically within 26 days 1, 3
• Determine smoking status - active smokers with chronic cough likely have chronic bronchitis; smoking cessation resolves cough within 4 weeks in most cases 1

Key Historical Elements

• Duration of symptoms: acute (<3 weeks), subacute (3-8 weeks), or chronic (>8 weeks) 1
• Associated symptoms: wheezing, postnasal drip, heartburn, sputum production 1, 3
• Timing and character of cough - though these features do not reliably predict etiology and should not be used to rule diagnoses in or out 1
• Environmental and occupational exposures 1

Diagnostic Approach Based on Chest Radiograph

If Chest Radiograph is Normal

Proceed with systematic evaluation for the three most common causes in sequential, additive steps since multiple conditions frequently coexist 1:

Step 1: Evaluate and Treat for UACS (Most Common)

• UACS is the most common cause of chronic cough (previously called postnasal drip syndrome) 1
• Clinical diagnosis is based on symptoms (nasal discharge, throat clearing, sensation of postnasal drip), physical findings (cobblestoning of posterior pharynx, mucus in oropharynx), and response to therapy 1
• Initiate empiric trial with first-generation antihistamine/decongestant combination - this is the recommended initial therapy 1
• If no response to antihistamine/decongestant, obtain sinus imaging to evaluate for chronic sinusitis 1
• Allow adequate treatment duration before moving to next diagnostic consideration 1

Step 2: Evaluate and Treat for Asthma (Second Most Common)

• Asthma accounts for 24-29% of chronic cough cases and may present with cough as the sole symptom (cough-variant asthma) 1
• Physical examination and spirometry may be entirely normal in cough-variant asthma 1
• Perform spirometry first - if reversible airflow obstruction is demonstrated, empiric asthma therapy is appropriate 1
• If spirometry is normal, perform methacholine inhalation challenge (MIC) testing to document bronchial hyperresponsiveness 1
• A negative MIC test essentially excludes asthma from the differential diagnosis due to its high negative predictive value 1
• Important caveat: A positive MIC test is consistent with but not diagnostic of asthma - definitive diagnosis requires documented resolution of cough with antiasthmatic therapy 1

Treatment approach for asthma-related cough:

• Start with inhaled bronchodilators and inhaled corticosteroids 1
• Add leukotriene receptor antagonists if inadequate response - these appear particularly effective for cough due to asthma 1
• Consider short course of oral corticosteroids for refractory cases 1

Step 3: Evaluate and Treat for Nonasthmatic Eosinophilic Bronchitis (NAEB)

• If UACS and asthma have been eliminated or treated without cough resolution, consider NAEB 1
• Perform induced sputum test for eosinophils if available 1
• If induced sputum testing unavailable, give empiric trial of corticosteroids 1

Step 4: Evaluate and Treat for GERD

• If cough responds only partially or not at all to interventions for UACS and asthma/NAEB, institute treatment for GERD 1
• GERD may be "silent" with no typical reflux symptoms yet still cause chronic cough 1
• Initiate empiric therapy rather than testing in patients with chronic cough and any reflux symptoms 3

If Chest Radiograph is Abnormal

Tailor investigation based on specific radiographic findings 1:

• Mass or findings suggesting malignancy: Proceed to chest CT, then bronchoscopy, transthoracic needle aspiration, or PET scan 1
• Interstitial pattern: Obtain high-resolution CT chest, consider bronchoscopy with transbronchoscopic biopsy or video-assisted thoracic surgery biopsy 1
• Evidence of COPD: Confirm with pulmonary function testing; determine if acute exacerbation requiring antibiotics or corticosteroids 1
• Congestive heart failure pattern: Pursue cardiovascular evaluation, consider empiric diuresis 1
• Infiltrate suggesting infection: Obtain microbiological diagnosis, especially if tuberculosis suspected 1

Advanced Testing When Initial Workup is Inconclusive

Pulmonary Function Testing

• Formal pulmonary function testing is the most useful diagnostic test for chronic dyspnea, particularly for COPD and asthma 4
• Obstructive pattern: Suggests asthma, chronic bronchitis, or bronchiectasis 5
• Restrictive pattern: Suggests interstitial lung disease, sarcoidosis, or pneumoconiosis 5

High-Resolution CT Chest

• CT is essential when radiographic abnormality requires characterization or clinical findings necessitate imaging despite normal radiograph 1
• Thin collimation of lung parenchyma is essential for dyspnea evaluation 1
• Particularly useful for: Interstitial lung disease, idiopathic pulmonary fibrosis, bronchiectasis, pulmonary embolism 1, 6
• IV contrast not routinely needed unless vascular abnormalities are in differential 1

Additional Testing

• Echocardiography and brain natriuretic peptide levels help establish diagnosis of congestive heart failure 6
• Methacholine bronchoprovocation challenge when baseline pulmonary function tests are normal and asthma or postviral bronchitis suspected 5, 4
• Comprehensive exercise testing useful for dyspnea due to psychogenic factors or deconditioning 4

Critical Management Principles

Sequential and Additive Approach

• Treat in sequential and additive steps because more than one cause frequently coexists - do not stop after finding one diagnosis 1
• Continue adding therapies until cough resolves rather than assuming a single etiology 1

Common Pitfalls to Avoid

• Do not rely on cough character or timing to rule diagnoses in or out - these features are too nonspecific 1
• Do not assume normal spirometry excludes asthma - proceed to methacholine challenge testing 1
• Do not assume absence of typical symptoms excludes a diagnosis - UACS, asthma, and GERD can each present with cough as the sole symptom 1
• Do not stop evaluation after treating one condition - multiple causes commonly coexist 1

When to Refer

• Refer to pulmonologist or cough specialist if diagnosis remains unclear after systematic evaluation of common causes 1
• Consider referral if high-resolution CT or specialized testing needed 1

Special Considerations for COPD Exacerbations

Indications for Hospitalization

• High-risk comorbidities (pneumonia, cardiac arrhythmia, congestive heart failure, diabetes mellitus, renal or liver failure) 1
• Inadequate response to outpatient management 1
• Marked increase in dyspnea, inability to eat or sleep due to symptoms 1
• Worsening hypoxemia, hypercapnia, or changes in mental status 1
• Inability of patient to care for self or lack of home support 1

ICU Admission Criteria

• Impending or actual respiratory failure 1
• Presence of other end-organ dysfunction (shock, renal, liver, or neurological disturbance) 1