What diagnostic tests should be performed on a 77-year-old male with remote lung cancer and right lower lobectomy presenting with acute dyspnea requiring admission?

Diagnostic Testing for 77-Year-Old Male with Remote Lung Cancer History Presenting with Acute Dyspnea

This patient requires point-of-care ultrasonography (POCUS) in addition to standard diagnostic testing, including chest radiography, electrocardiogram, BNP/NT-proBNP, complete blood count, basic metabolic panel, and arterial blood gas, with particular attention to cardiac causes given his age and surgical history. 1, 2

Initial Standard Diagnostic Pathway

The foundational workup must include:

• Chest radiography (PA and lateral) to identify cardiomegaly, pulmonary congestion, pleural effusion, pneumonia, masses, or recurrent malignancy 1, 3
• Electrocardiogram to detect ischemic changes, arrhythmias, or chamber enlargement 3
• BNP or NT-proBNP measurement - values <100 pg/mL (BNP) or <125 pg/mL (NT-proBNP) effectively exclude heart failure 1, 3
• Arterial blood gas analysis to assess oxygenation, ventilation, and acid-base status 4
• Complete blood count to evaluate for anemia or infection 4
• Basic metabolic panel including renal function 4

Point-of-Care Ultrasonography Protocol

POCUS should be performed when diagnostic uncertainty exists after initial evaluation, as it significantly improves diagnostic accuracy and reduces time to diagnosis from 186 minutes to 24 minutes. 1, 2, 5

The focused ultrasonographic examination should assess:

• Pulmonary evaluation: Look for B-lines (indicating interstitial edema), lung consolidation, pleural effusion, and pneumothorax 2, 5
• Cardiac evaluation: Assess left ventricular systolic and diastolic function, right ventricular strain, pericardial effusion, and valvular abnormalities 1, 2, 6
• Inferior vena cava assessment: Evaluate volume status and right heart function 2, 5

POCUS improves sensitivity for detecting heart failure, pneumonia, pulmonary embolism, pleural effusion, and pneumothorax, though it performs less well for COPD/asthma diagnosis compared to standard evaluation. 5

Critical Considerations for This Patient's History

Given the 10-year interval since lobectomy without recurrence, focus diagnostic efforts on new cardiopulmonary pathology rather than cancer recurrence, though chest imaging remains essential. 4

Key factors influencing the diagnostic approach:

• Post-lobectomy status increases risk for reduced pulmonary reserve and may complicate interpretation of imaging and pulmonary function 7
• Advanced age (77 years) increases likelihood of cardiac causes, particularly heart failure with preserved ejection fraction (HFpEF) and coronary artery disease 3
• Remote cancer history without treatment suggests low immediate risk of recurrence, but imaging must still evaluate for this possibility 4

Diagnostic Algorithm Based on Initial Results

If BNP/NT-proBNP is elevated and POCUS shows multiple B-lines with decreased ventricular function: Diagnosis is acute decompensated heart failure; proceed with echocardiography for comprehensive cardiac assessment 2, 6, 3

If chest radiograph shows infiltrate with fever/leukocytosis: Diagnosis is pneumonia; POCUS can confirm consolidation and guide antibiotic therapy 2, 5

If initial testing is unrevealing but dyspnea persists: Consider pulmonary function testing with spirometry and diffusing capacity (DLCO), as post-lobectomy patients may have severe DLCO impairment despite minimal spirometric abnormalities 7

If resting tests remain normal: Cardiopulmonary exercise testing (CPET) definitively distinguishes cardiac, pulmonary, vascular, and deconditioning causes 3

Common Pitfalls to Avoid

• Do not rely on history and physical examination alone - they have high specificity (96%) but low sensitivity (59%) for cardiac causes 3
• Normal chest radiography does not exclude cardiac disease, particularly early heart failure or diastolic dysfunction 3
• Absence of peripheral edema does not exclude heart failure, as many patients with HFpEF present without edema 3
• Do not use POCUS as a replacement for complete clinical evaluation - it is a complement when uncertainty exists, not a standalone diagnostic tool 1, 2
• POCUS requires adequate operator training for correct real-time interpretation 2

Timing and Sequence

Complete the standard diagnostic pathway first (history, vital signs, physical examination, ECG, chest radiography) before adding POCUS. 2 This approach ensures systematic evaluation while POCUS provides rapid additional diagnostic information when the initial workup is ambiguous. 1, 5

The integrated approach reduces time to diagnosis while maintaining diagnostic accuracy comparable to standard evaluation for most causes of dyspnea. 5