What is the initial approach to a patient presenting with shortness of breath?

Initial Approach to a Patient Presenting with Shortness of Breath

The initial assessment of a patient with shortness of breath should begin with an 'ABCDE' (Airway, Breathing, Circulation, Disability, Exposure) evaluation, followed by immediate oxygen therapy if oxygen saturation is below target, and then a focused history and physical examination to determine the underlying cause. 1

Immediate Assessment and Stabilization

Step 1: Airway, Breathing, Circulation (ABC) Assessment

• Assess airway patency
• Evaluate breathing pattern and respiratory effort
• Check circulation (pulse rate, blood pressure)
• Record vital signs including respiratory rate, pulse rate, blood pressure, temperature, and oxygen saturation via pulse oximetry 1

Step 2: Oxygen Administration

• For patients with oxygen saturation below 85% without risk of hypercapnic respiratory failure: Start with reservoir mask at 15 L/min
• For patients with oxygen saturation below target but above 85% without risk factors for hypercapnic respiratory failure: Start with nasal cannulae (1-6 L/min) or simple face mask (5-10 L/min)
• For patients with known COPD or at risk of hypercapnic respiratory failure: Use titrated oxygen therapy to achieve target saturation of 88-92% 1
• Monitor oxygen saturation continuously until the patient is stable

Diagnostic Approach

Step 3: Focused History

• Onset and duration of shortness of breath
• Precipitating factors and alleviating factors
• Associated symptoms (chest pain, cough, fever, orthopnea, etc.)
• Past medical history (cardiac, pulmonary, or other conditions)
• Medication history
• Smoking history and occupational exposures 1

Step 4: Physical Examination

• Signs of respiratory distress: Use of accessory muscles, nasal flaring, intercostal retractions
• Vital signs: Tachypnea, tachycardia, hypotension, fever
• Respiratory system: Decreased breath sounds, wheezing, crackles, pleural rub
• Cardiovascular system: Jugular venous distention, S3 gallop, murmurs, peripheral edema
• General assessment: Cyanosis, altered mental status 1, 2

Step 5: Initial Diagnostic Tests

1. Pulse oximetry (all patients)
2. ECG (especially for suspected cardiac causes)
3. Chest radiography (first-line imaging study)
4. Basic laboratory tests:
   • Complete blood count
   • Electrolytes and creatinine
   • Brain natriuretic peptide (BNP/NT-proBNP) to help distinguish cardiac from pulmonary causes 1, 2
5. Arterial blood gases (for critically ill patients, unexpected fall in SpO2 below 94%, deteriorating oxygen saturation, or suspected metabolic conditions) 1

Common Causes and Specific Management

Cardiac Causes

• Heart Failure: Look for jugular venous distention, S3 gallop, peripheral edema, bilateral crackles

  • BNP/NT-proBNP measurement (optimal cutoff for BNP: 100 pg/mL; sensitivity 0.98, specificity 0.47) 2
  • Echocardiography to distinguish between HFpEF and HFrEF 1

• Acute Coronary Syndrome: Look for chest pain, diaphoresis, nausea

  • ECG changes
  • Cardiac biomarkers

Pulmonary Causes

• COPD/Asthma Exacerbation: Look for wheezing, prolonged expiration, barrel chest

  • Bronchodilator therapy
  • Consider corticosteroids
  • For severe asthma: Use lower tidal volumes if mechanical ventilation is needed 1

• Pneumonia: Look for fever, productive cough, localized crackles

  • Appropriate antibiotics based on likely pathogens

• Pulmonary Embolism: Look for tachycardia, pleuritic chest pain, risk factors

  • D-dimer testing (if negative, helps rule out PE)
  • CT pulmonary angiogram if clinical suspicion is high or D-dimer is positive 1

• Pneumothorax: Look for unilateral decreased breath sounds, tracheal deviation (if tension)

  • Immediate needle decompression for tension pneumothorax 1

Other Causes

• Anemia: Look for pallor, fatigue

  • Complete blood count

• Metabolic Acidosis: Look for Kussmaul breathing

  • Arterial blood gases
  • Electrolytes and glucose

Special Considerations and Pitfalls

Important 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 2, 1

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

3. Attributing shortness of breath to poor conditioning - When underlying pathology exists 1

4. Missing cardiac arrest - Unconscious patients with abnormal or absent breathing should be presumed to be in cardiac arrest and CPR should be started immediately 1

5. Overlooking multiple causes - In about one-third of patients, the etiology of dyspnea is multifactorial 3

Recognizing Life-Threatening Conditions

• Tension pneumothorax: Unilateral chest movement, tracheal deviation, hypotension
• Severe asthma/COPD: Silent chest, cyanosis, altered mental status
• Pulmonary edema: Frothy sputum, diffuse crackles
• Anaphylaxis: Urticaria, angioedema, stridor, wheezing

Follow-up Investigations

Based on initial assessment and suspected diagnosis, consider:

• Pulmonary function testing for suspected obstructive or restrictive lung disease
• Echocardiography for suspected heart failure, valvular disease, or pulmonary hypertension
• CT chest for suspected interstitial lung disease, bronchiectasis, or other parenchymal lung diseases
• Cardiopulmonary exercise testing for unexplained dyspnea when initial testing is normal 1

Remember that the initial approach must be systematic, prioritizing immediate stabilization while simultaneously pursuing diagnostic evaluation to determine the underlying cause.