What is the initial workup for a patient presenting with shortness of breath?

Initial Workup for Shortness of Breath

The initial workup for a patient presenting with shortness of breath should begin with immediate assessment of airway, breathing, circulation (ABC), pulse oximetry, vital signs (heart rate, respiratory rate, blood pressure), and targeted diagnostic testing based on oxygen saturation and clinical presentation. 1

Immediate Assessment and Stabilization

First Responder Evaluation

• Perform ABC assessment immediately upon encountering any breathless patient 1
• Measure pulse oximetry in all patients with breathlessness or suspected hypoxemia—this is mandatory and should never be omitted 1
• Record pulse rate and respiratory rate as part of initial vital signs 1
• Obtain a brief focused history from the patient or family regarding onset, duration, associated symptoms, and relevant medical history 1

Oxygen Therapy Initiation

• Start oxygen therapy immediately if SpO2 is below target range (94-98% for most patients, 88-92% for those at risk of hypercapnic respiratory failure such as COPD) 1
• Use reservoir mask at 15 L/min if initial SpO2 is below 85%, otherwise use nasal cannula at 2-6 L/min or simple face mask at 5-10 L/min 1
• For patients with known COPD or risk factors for hypercapnia, target SpO2 of 88-92% pending arterial blood gas results 1

Essential Initial Diagnostic Testing

Laboratory Studies

• Obtain BNP or NT-proBNP level as the single most important test when initial cardiac and pulmonary workup is unrevealing—a BNP <100 pg/mL has 96-99% sensitivity for ruling out heart failure 2
• Complete blood count with differential to evaluate for anemia, infection, or inflammatory processes 3
• Basic metabolic panel to assess for metabolic acidosis, renal dysfunction, or electrolyte abnormalities 4
• Arterial blood gas if hypoxemia is present or COPD/hypercapnia is suspected, particularly if SpO2 <92% or patient has risk factors for CO2 retention 1

Imaging Studies

• Chest radiography is the initial imaging test to identify consolidations, ground-glass opacities, pleural effusions, pneumothorax, cardiomegaly, or pulmonary edema 3, 4
• Electrocardiography in all patients to evaluate for acute coronary syndromes, arrhythmias, or signs of right heart strain 4

Algorithmic Approach Based on Initial Findings

If BNP is Elevated (≥100 pg/mL)

• Proceed to echocardiography to assess for heart failure with preserved ejection fraction (HFpEF), systolic dysfunction, valvular disease, diastolic dysfunction, pulmonary hypertension, or pericardial disease 1, 2
• Do not assume a negative stress test excludes cardiac causes—stress testing primarily rules out obstructive coronary disease but not HFpEF, valvular disease, or pulmonary hypertension 2

If BNP is Normal (<100 pg/mL) and Initial Workup Unrevealing

• Consider cardiopulmonary exercise testing (CPET) to distinguish between cardiac, pulmonary, and deconditioning causes when resting tests are normal 1, 2
• CPET can identify exercise-induced limitations, deconditioning, exercise-induced bronchoconstriction, or exercise-induced arterial hypoxemia that are not apparent on resting studies 2

If Fever is Present

• Obtain respiratory pathogen panel including COVID-19 RT-PCR, influenza A/B, and other viral pathogens 3
• Check inflammatory markers (CRP, procalcitonin) to help distinguish bacterial from viral etiologies 3
• Aggressively exclude pulmonary embolism in any patient with subacute dyspnea, particularly when symptoms are slow to respond or worsen—pneumonia can mask PE when fever predominates 3

Disease-Specific Measurements

Based on Clinical Presentation

• Peak expiratory flow in suspected asthma to assess severity of airflow obstruction 1
• Spirometry if COPD or restrictive lung disease is suspected and patient is stable enough for testing 4
• D-dimer testing may help rule out pulmonary emboli in appropriate clinical contexts 4

Common Pitfalls to Avoid

• Do not delay oxygen therapy waiting for formal prescription—oxygen should be given immediately in emergencies with documentation afterward 1
• Do not rely on clinical assessment alone—it has high specificity (96%) but low sensitivity (59%) for cardiac causes, making biomarker testing essential 2
• Do not dismiss pulmonary embolism based solely on absence of classic symptoms, as other conditions can mask PE presentation 3
• Do not assume absence of cough excludes pneumonia—10-20% of viral pneumonias present with dyspnea and fever without prominent cough 3
• Monitor oxygen saturation continuously until the patient is stable, adjusting oxygen concentration to maintain target range 1

Further Evaluation if Initial Workup is Negative

• CT chest to evaluate for interstitial lung disease, pulmonary vascular abnormalities, or subtle parenchymal disease not visible on plain radiography 2, 4
• Pulmonary function studies to identify emphysema, interstitial lung diseases, or restrictive patterns 4
• Consider referral to cardiology if echocardiography reveals valvular disease, HFpEF, or cardiac etiology remains suspected despite negative initial testing 2
• Consider referral to pulmonology for evaluation of interstitial lung disease, pulmonary vascular disease, or if CPET suggests pulmonary limitation 2