What is the likely diagnosis for an individual, possibly an older adult or with underlying health conditions, presenting with chest congestion and shortness of breath (SOB)?

Differential Diagnosis for Chest Congestion and Shortness of Breath

The most likely diagnoses to consider are lower respiratory tract infection (pneumonia or acute bronchitis), cardiac failure, COPD exacerbation, or pulmonary embolism, with the specific diagnosis determined by age, risk factors, and clinical findings. 1

Diagnostic Algorithm Based on Clinical Presentation

Primary Assessment Framework

The European Respiratory Society emphasizes that when patients present with cough and dyspnea, you must first distinguish between infectious causes (pneumonia, acute bronchitis) and non-infectious disorders (asthma, COPD, heart failure, or pulmonary embolism). 1

Age-Specific Considerations

For patients aged >65 years:

• Cardiac failure should be strongly considered if any of the following are present: orthopnea, displaced apex beat, history of myocardial infarction, hypertension, or atrial fibrillation 1, 2
• Low serum BNP (<40 pg/mL) or NT pro-BNP (<150 pg/mL) effectively rules out left ventricular failure 1, 2
• Older age, male sex, and orthopnea are specific predictors of cardiac failure in this population 1

Pneumonia vs. Other Lower Respiratory Tract Infections

Suspect pneumonia when ANY of the following are present:

• New focal chest signs on examination 1
• Dyspnea with tachypnea 1
• Pulse rate >100 beats/minute 1
• Fever persisting >4 days 1

Use C-reactive protein (CRP) testing strategically:

• CRP <20 mg/L at presentation (with symptoms >24 hours) makes pneumonia highly unlikely 1, 2
• CRP >100 mg/L makes pneumonia likely 1, 2
• If doubt persists after CRP testing, obtain chest X-ray to confirm or exclude pneumonia 1

COPD Exacerbation Recognition

Consider COPD exacerbation in patients with:

• Persistent cough plus at least two of: wheezing (sign or symptom), previous consultations for wheezing/cough, dyspnea, prolonged expiration, smoking history, or symptoms of allergy 1
• In elderly smokers presenting with cough, COPD should be the primary consideration 1
• Cardinal symptoms include increased dyspnea, increased sputum purulence and volume, and increased cough and wheeze 3

Severity assessment requires:

• Evaluation of tachypnea, tachycardia, use of accessory respiratory muscles, central cyanosis, and evidence of respiratory muscle dysfunction 3
• Critical warning sign: A paradoxically low respiratory rate suggests respiratory muscle fatigue with impending respiratory arrest 3
• Arterial blood gas, chest X-ray, ECG, and pulse oximetry are mandatory for severity determination 3

Pulmonary Embolism Screening

PE should be considered in patients with ANY of:

• History of DVT or previous pulmonary embolism 1, 2
• Immobilization in the past 4 weeks 1, 2
• Active malignant disease 1

The absence of ALL these factors plus no signs of DVT, no haemoptysis, pulse <100, and no malignancy makes PE highly unlikely. 1

Aspiration Pneumonia Consideration

Aspiration pneumonia must be considered in patients with:

• Difficulties with swallowing who show signs of acute LRTI 1
• History of cerebrovascular events or certain psychiatric diseases 1
• These patients require chest radiograph 1

Critical Pitfalls to Avoid

Do not rely on symptoms alone for severity assessment—physical signs have poor sensitivity and reliability, requiring objective measurements including arterial blood gas analysis. 3

Do not assume younger patients without smoking history cannot have serious pathology—bronchogenic carcinoma must be ruled out in all patients with persistent pulmonary symptoms, with mean age of diagnosis being 64 years. 2

Do not overlook the combination of risk factors—former smokers with environmental exposure to airway irritants (including animal waste) have additive risk for respiratory complications and recurrent pneumonia. 4

Immediate Diagnostic Workup Required

• Arterial blood gas analysis noting inspired oxygen concentration to distinguish simple hypoxemia from hypercapnic respiratory failure 3, 2
• Chest radiograph urgently to identify pneumonia, pulmonary edema, pleural effusions, pneumothorax, or masses 2
• CRP testing if pneumonia suspected 1, 2
• BNP or NT pro-BNP if cardiac failure suspected in patients >65 years 1, 2