What is the diagnostic workup for a 58-year-old man with progressive shortness of breath?

Diagnostic Workup for Progressive Shortness of Breath in a 58-Year-Old Man

The diagnostic workup for a 58-year-old man with progressive shortness of breath should begin with oxygen saturation assessment, chest imaging, electrocardiogram, basic laboratory tests, and pulmonary function testing, followed by specialized testing such as echocardiography and cardiopulmonary exercise testing to differentiate between cardiac, pulmonary, and other causes. 1

Initial Assessment

History

• Timing and progression: Onset (sudden vs. gradual), duration, and progression
• Triggers: Exertion, position (orthopnea), time of day (paroxysmal nocturnal dyspnea)
• Associated symptoms:
  • Cardiac: Chest pain, palpitations, edema, orthopnea
  • Pulmonary: Cough, sputum, wheezing, hemoptysis
  • Other: Fatigue, weight loss, fever

Physical Examination

• Vital signs: Oxygen saturation, respiratory rate, heart rate, blood pressure
• Cardiac: Jugular venous pressure, heart sounds (S3, murmurs), peripheral edema
• Pulmonary: Respiratory effort, wheezing, crackles, percussion note
• Other: Signs of systemic disease (telangiectasia, clubbing, cyanosis)

First-Line Diagnostic Tests

1. Oxygen saturation: At rest and with exertion 1
2. Chest radiograph: To evaluate for pulmonary congestion, infiltrates, masses, or structural abnormalities 2
3. Electrocardiogram (ECG): To assess for arrhythmias, ischemia, or right ventricular strain 2
   • Note: A normal ECG does not exclude pulmonary hypertension 2
4. Basic laboratory tests:
   • Complete blood count (anemia)
   • Basic metabolic panel (renal function)
   • BNP/NT-proBNP (heart failure)
   • D-dimer (if pulmonary embolism suspected)

Second-Line Diagnostic Tests

Pulmonary Evaluation

• Pulmonary function tests (PFTs): Essential for suspected respiratory causes 1, 3
  • Spirometry with bronchodilator reversibility testing
  • Lung volumes and diffusion capacity
  • Note: In one study, less than 41% of patients treated for shortness of breath with inhalers had ever undergone PFTs 3

Cardiac Evaluation

• Echocardiography: For suspected cardiac causes 2, 1
  • Evaluates ventricular function, valvular disease, and pulmonary pressures
  • Particularly important if history suggests heart failure or valvular disease

Advanced Imaging

• High-resolution CT scan: If interstitial lung disease or pulmonary nodules are suspected 2
• CT pulmonary angiography: If pulmonary embolism is suspected

Specialized Testing

Cardiopulmonary Exercise Testing (CPET)

• Gold standard for differentiating between cardiac, pulmonary, and other causes of exertional dyspnea 1
• Provides objective measurements of:
  • Exercise capacity (VO₂max)
  • Ventilatory efficiency (VE/VCO₂)
  • Oxygen pulse
  • Breathing reserve
  • Evidence of exercise-induced hypoxemia

CPET Interpretation

• Cardiovascular limitation: Reduced O₂ pulse, early plateau in O₂ pulse-VO₂ relationship, abnormal heart rate response 1, 2
• Pulmonary limitation: Reduced breathing reserve (<15%), O₂ desaturation, increased VE/VCO₂ slope 1
• Peripheral limitation: Normal cardiac and ventilatory responses with reduced anaerobic threshold 1
• Deconditioning: Reduced VO₂max with normal physiologic responses 1

Additional Testing Based on Initial Findings

• Right heart catheterization: If pulmonary hypertension is suspected 2
• Ventilation/perfusion (V/Q) scan: For suspected chronic thromboembolic pulmonary hypertension 2
• Bronchoscopy: For suspected airway disease or to obtain samples for cytology/microbiology

Diagnostic Algorithm

1. Initial evaluation: History, physical exam, oxygen saturation, chest X-ray, ECG, and basic labs
2. If cardiac etiology suspected (based on history, exam, BNP):
   • Echocardiography
   • Consider stress testing or coronary evaluation if ischemia suspected
3. If pulmonary etiology suspected (based on history, exam, chest X-ray):
   • Complete PFTs
   • Consider high-resolution CT chest
4. If diagnosis remains unclear after initial workup:
   • Cardiopulmonary exercise testing
   • Consider specialized testing based on leading differential diagnoses

Common Pitfalls to Avoid

• Assuming all shortness of breath in older adults is cardiac: Up to 28.4% of patients treated for shortness of breath with inhalers have no evidence of obstructive airway disease 3
• Failing to obtain objective pulmonary function testing: Essential before initiating treatment for presumed obstructive airway disease 3
• Missing pulmonary hypertension: Can present with nonspecific symptoms and normal ECG 2
• Overlooking non-cardiopulmonary causes: Such as anemia, deconditioning, or neuromuscular disorders
• Inadequate exercise testing: Submaximal tests (below 85% of predicted maximum heart rate) may miss significant pathology 1

By following this systematic approach, the underlying cause of progressive shortness of breath in a 58-year-old man can be accurately diagnosed, allowing for appropriate treatment to reduce morbidity and mortality and improve quality of life.