What is the approach to a patient presenting with shortness of breath (SOB)?

Approach to a Patient Presenting with Shortness of Breath (SOB)

The initial approach to a patient with shortness of breath must follow the ABCDE (Airway, Breathing, Circulation, Disability, Exposure) algorithm to identify and treat life-threatening conditions immediately, while simultaneously pursuing diagnostic evaluation to determine the underlying cause.

Initial Assessment and Stabilization

1. Airway and Breathing Assessment

• Assess airway patency and respiratory effort
• Evaluate for signs of respiratory distress:
  • Abnormal breathing patterns
  • Use of accessory muscles
  • Inability to speak in full sentences
  • Agonal breathing (may indicate cardiac arrest) 1
• Measure oxygen saturation
• Administer supplemental oxygen if hypoxemic 1

2. Circulation Assessment

• Check pulse, blood pressure, and perfusion
• Assess for signs of shock or cardiac compromise
• Obtain IV access if moderate to severe distress

3. Disability and Exposure

• Assess mental status
• Fully expose patient to look for additional clues (rashes, edema, etc.)

Immediate Life-Threatening Conditions to Rule Out

1. Cardiac Arrest: If unconscious with abnormal or absent breathing, assume cardiac arrest and begin CPR immediately 1
2. Tension Pneumothorax: Look for unilateral chest movement, tracheal deviation, hypotension 1
3. Severe Asthma/COPD Exacerbation: Assess for silent chest, cyanosis, altered mental status 1
4. Pulmonary Edema: Assess for crackles, frothy sputum, JVD
5. Pulmonary Embolism: Check for risk factors, hypoxemia disproportionate to exam
6. Anaphylaxis: Look for urticaria, angioedema, hypotension

Diagnostic Approach

1. Initial Imaging and Testing

• Chest X-ray: First-line imaging study for all patients with SOB 2
  • Can identify COPD changes, interstitial disease, pleural effusions, cardiomegaly, pulmonary edema
  • May result in specific diagnosis in one-third of cases 2
• ECG: To evaluate for cardiac causes
• Basic labs: CBC, electrolytes, BUN/creatinine, glucose
• Specific labs based on suspicion:
  • B-natriuretic peptide: To distinguish cardiac from pulmonary causes 2
  • D-dimer: If pulmonary embolism suspected
  • Arterial blood gas: For severe respiratory distress or suspected metabolic derangement

2. Categorizing the Cause

Cardiac Causes

• Heart failure (acute or chronic)
• Valvular heart disease
• Arrhythmias
• Pericardial disease

Pulmonary Causes

• Obstructive lung disease (asthma, COPD)
• Restrictive lung disease (interstitial lung disease)
• Pulmonary vascular disease (pulmonary embolism, pulmonary hypertension)
• Pleural disease
• Pneumonia/infection

Other Causes

• Anemia
• Metabolic acidosis
• Neuromuscular disorders
• Anxiety/panic disorder
• Deconditioning

Specific Management Based on Etiology

Asthma/COPD Exacerbation

• Administer bronchodilators (albuterol 2.5mg nebulized every 20 minutes for first hour) 3
• Consider systemic corticosteroids
• For severe asthma with risk of respiratory arrest:
  • Use lower tidal volumes and respiratory rates if mechanical ventilation needed
  • Watch for air trapping and auto-PEEP 1
  • Brief disconnection from ventilator may be needed if hyperinflation occurs 1

Heart Failure

• Perform echocardiography to assess cardiac function, valvular disease 1
• Distinguish between heart failure with preserved ejection fraction (HFpEF) and reduced ejection fraction (HFrEF) 1
• Consider comorbidities that may contribute to HFpEF (hypertension, atrial fibrillation, obesity, diabetes) 1

Pulmonary Embolism

• If clinical suspicion is high or D-dimer positive, obtain CT pulmonary angiogram 2

Pneumonia

• Obtain appropriate cultures
• Initiate empiric antibiotics based on clinical presentation and local resistance patterns

Special Considerations

Unexplained Dyspnea

• If initial workup is unrevealing, consider:
  • Cardiopulmonary exercise testing to distinguish between cardiac, pulmonary, or deconditioning causes 2
  • High-resolution CT chest if interstitial lung disease suspected 2
  • Echocardiography if pulmonary hypertension suspected 2

Mimics of Common Conditions

• Consider cardiac amyloidosis in patients with HFpEF and specific risk factors 1
• Evaluate for vocal cord dysfunction in younger patients with SOB who don't respond to asthma treatment 4

Common Pitfalls to Avoid

1. Failing to recognize agonal breathing as a sign of cardiac arrest - Dispatchers and providers should be educated to identify abnormal breathing patterns that may indicate cardiac arrest 1

2. Attributing SOB solely to deconditioning without adequate workup - Always perform appropriate diagnostic testing to rule out pathologic causes 2

3. Missing cardiac causes of dyspnea - Heart failure, valvular disease, and pulmonary hypertension can present primarily with exertional dyspnea 1, 2

4. Proceeding to advanced imaging without baseline chest X-ray - This may lead to unnecessary radiation exposure and cost 2

5. Over-ventilating asthma patients - Can worsen air trapping and lead to barotrauma or decreased venous return 1

By following this systematic approach, clinicians can effectively assess, stabilize, and diagnose patients presenting with shortness of breath while avoiding common diagnostic and therapeutic pitfalls.