What is the appropriate initial evaluation and treatment for a patient with difficulty breathing, considering their age, medical history, and current symptoms, including any previous respiratory conditions such as Chronic Obstructive Pulmonary Disease (COPD) or asthma?

Initial Evaluation and Management of Difficulty Breathing

Begin with immediate assessment of severity and oxygen status, followed by targeted history focusing on smoking exposure, symptom chronicity, and cardiac risk factors, then confirm suspected diagnoses with spirometry for airflow limitation or BNP/chest imaging for cardiac causes. 1

Immediate Assessment and Stabilization

Oxygen Therapy

• Target oxygen saturation of 94-98% for most patients using nasal cannulae at 2-6 L/min or simple face mask at 5-10 L/min 1
• If COPD is suspected based on smoking history or physical findings, consider lower target of 88-92% pending arterial blood gas results, then adjust to 94-98% if PCO2 is normal 1
• Arterial blood gas analysis is mandatory to distinguish simple hypoxemia from hypercapnic respiratory failure 1
• Recheck blood gases after 30-60 minutes of oxygen therapy 1

Urgent Diagnostic Studies

• Chest radiograph must be obtained urgently to identify pneumonia, pulmonary edema, pleural effusions, pneumothorax, or lung masses 1
• CT chest is superior to plain radiography for detecting pulmonary nodules if lung cancer is suspected 1

Targeted History Taking

Critical Historical Elements

Assess the following specific issues systematically: 2

• Smoking history and quantification - tobacco smoke is by far the most important risk factor for COPD worldwide 2
• Symptom pattern: chronic cough (often first symptom of COPD), sputum production for 3+ months in 2 consecutive years, progressive dyspnea, wheezing, chest tightness 2
• Age and onset: COPD typically presents in patients aged 25-75 years with insidious progression over years 2
• Cardiac risk factors: age >65 years, orthopnea, history of myocardial infarction, hypertension, or atrial fibrillation suggests left ventricular failure 1
• Acute features: new focal chest signs, fever >4 days, pulse >100 suggests pneumonia 1
• Recent immobilization or DVT history suggests pulmonary embolism 1

Additional History Components

• Past medical history of asthma, allergies, other respiratory diseases 2
• Family history of COPD or chronic respiratory diseases 2
• Occupational and environmental exposures 2
• Pattern of exacerbations or previous hospitalizations 2
• Unexplained weight loss, fatigue, anorexia (suggests severe disease or malignancy) 2
• Co-morbidities including heart disease, osteoporosis, malignancies 2

Physical Examination

Key Physical Findings

• Measure respiratory rate, weight, height, and BMI in all patients 2
• Normal physical examination is common in early COPD; physical signs typically appear only with significantly impaired lung function 2
• Look for displaced apex beat (suggests cardiac dysfunction) 1
• Assess for signs of respiratory distress, use of accessory muscles, pursed-lip breathing 2

Important caveat: A normal physical examination does not exclude significant respiratory disease, particularly early COPD 2

Diagnostic Testing Algorithm

First-Line Confirmatory Tests

For suspected COPD:

• Spirometry is required to make the diagnosis - a post-bronchodilator FEV1/FVC <0.70 confirms persistent airflow limitation 2
• Spirometry should be performed in any patient with dyspnea, chronic cough, or sputum production with exposure to risk factors 2
• Good-quality spirometry is possible in any healthcare setting 2

For suspected cardiac causes:

• BNP or NT pro-BNP: levels <40 pg/mL (BNP) or <150 pg/mL (NT pro-BNP) make left ventricular failure unlikely 1
• Consider echocardiography if cardiac dysfunction suspected 1

For suspected pneumonia:

• CRP level >100 mg/L makes pneumonia likely, while <20 mg/L with symptoms >24 hours makes it highly unlikely 1
• Chest radiograph for confirmation 1

Critical Differential Diagnoses Not to Miss

Bronchogenic carcinoma:

• Must be ruled out in all patients with persistent pulmonary symptoms, even without smoking history 1
• Mean age of lung cancer diagnosis is 64 years 1
• Never assume COPD or chronic bronchitis explains a focal density on imaging 3
• For nodules >1.5 cm in high-risk patients, biopsy is usually appropriate 3

Pulmonary embolism:

• Consider with history of DVT, recent immobilization (past 4 weeks), or malignancy 1

Foreign body aspiration:

• Can mimic COPD exacerbation with persistent wheezing despite appropriate therapy 4
• Consider bronchoscopy if symptoms fail to respond to standard treatment 4

Initial Treatment Based on Suspected Diagnosis

For COPD Exacerbation

• Initiate or increase bronchodilators: β2-agonists and/or anticholinergics 2
• Antibiotics if sputum becomes purulent: 7-14 day course with amoxicillin, tetracycline derivatives, or amoxicillin/clavulanic acid based on local resistance patterns 2
• Systemic corticosteroids for moderate to severe exacerbations 2
• Encourage sputum clearance by coughing 2
• Avoid sedatives and hypnotics 2

For Suspected Heart Failure

• Diuretics, vasodilators, and oxygen therapy targeting 94-98% saturation 1
• Consider CPAP or non-invasive ventilation for pulmonary edema 1

For Suspected Pneumonia

• Antibiotic selection should follow local resistance patterns, with broader coverage than simple amoxicillin for community-acquired pneumonia in elderly patients 1

Common Pitfalls to Avoid

• Do not over-diagnose COPD in patients with systolic heart failure and dyspnea - concomitant conditions are common 5
• Do not assume a single diagnosis explains all symptoms when comorbidities are present 5
• Do not delay investigation with "wait and see" approach for pulmonary nodules in high-risk patients 3
• Do not miss foreign body aspiration in patients with persistent wheezing unresponsive to standard COPD therapy 4
• Physical examination alone is insufficient - spirometry is required to confirm COPD 2

Smoking Cessation as Primary Intervention

Treating tobacco use should be regarded as a primary and specific intervention 2

• Ask systematically about tobacco use at every visit 2
• Advise strongly all tobacco users to quit in a clear, strong, personalized manner 2
• Assess willingness to make a quit attempt 2
• Assist with quit plan: provide practical counseling, recommend approved pharmacotherapy (nicotine replacement, behavioral intervention), arrange social support 2
• Arrange follow-up contact in person or via telephone 2

Smoking cessation is the only intervention proven to reduce mortality and slow disease progression in COPD 2