What is the initial workup for a patient experiencing orthopnea (shortness of breath when laying down)?

Initial Workup for Orthopnea (Shortness of Breath When Laying Down)

Begin with a thorough history focusing on cardiac symptoms (paroxysmal nocturnal dyspnea, edema, weight gain, fatigue, angina) and perform a targeted physical examination looking for elevated jugular venous pressure, S3 heart sound, pulmonary rales, peripheral edema, and cardiac murmurs, as these findings strongly suggest heart failure as the underlying cause. 1

Essential History Elements

When evaluating orthopnea, document the following specific details:

• Number of pillows required for comfortable sleep or whether the patient sleeps in a chair/recliner to maintain comfortable breathing 1
• Presence of paroxysmal nocturnal dyspnea (awakening suddenly from sleep with breathlessness relieved by sitting upright, lasting >5 minutes) 1
• Recent weight gain (amount in pounds/kilograms and timeframe), which suggests volume overload 1
• Swelling or puffiness in extremities or abdomen 1
• Fatigue and inability to perform usual activities 1
• Dyspnea on exertion with specific activity level that triggers symptoms (walking distance on flat surface, climbing stairs, dressing) 1
• Angina symptoms (chest pain, pressure, jaw or arm pain) using Canadian Cardiovascular Society classification 1

Physical Examination Priorities

Focus your examination on these cardiac-specific findings:

• Heart sounds: Listen for S3 gallop (indicates ventricular dysfunction), pericardial knock (suggests constriction), or murmurs (valve insufficiency) 1
• Heart rate and rhythm abnormalities 1
• Peripheral edema in lower extremities 1
• Elevated jugular venous pressure 1
• Pulmonary rales on auscultation 1

Initial Diagnostic Testing

Order these baseline tests immediately for all patients with orthopnea:

First-Line Laboratory and Imaging Studies

• Brain natriuretic peptide (BNP) or NT-proBNP - This is the single most important initial test for orthopnea 1

  • BNP <100 pg/mL has 96-99% sensitivity for ruling out heart failure 1
  • BNP >500 pg/mL strongly suggests cardiac etiology 1
  • For patients with renal disease (GFR <60 mL/min), use higher cutoffs 1

• Chest radiography to evaluate for pulmonary edema, cardiomegaly, pleural effusions, or alternative pulmonary pathology 1

• Electrocardiogram (ECG) to identify arrhythmias, ischemic changes, or conduction abnormalities 1

• Complete blood count to rule out anemia as a contributing factor 1, 2

• Basic metabolic panel (electrolytes, creatinine) to assess renal function and electrolyte abnormalities 1

• Pulse oximetry to document hypoxemia 1, 3

Second-Line Testing When Initial Workup is Non-Diagnostic

• Echocardiography - This is the definitive test when cardiac etiology is suspected based on history, physical exam, or elevated BNP 1

  • Evaluates left ventricular function, valvular disease, pericardial pathology, and right ventricular dysfunction 1
  • Point-of-care echocardiography can expedite diagnosis and has been shown to reduce time to treatment (83 vs 180 days) and improve outcomes (15% vs 28% hospitalization/death) 1

• Spirometry if pulmonary disease is suspected despite cardiac presentation 1, 4

• Arterial blood gas if severe respiratory distress or acid-base abnormality suspected 1

Common Diagnostic Pitfalls to Avoid

Do not rely on patient-reported symptoms alone without objective testing - Self-reported breathlessness has poor diagnostic accuracy and requires confirmation with BNP measurement and/or echocardiography 1, 4

Do not start therapeutic trials without establishing a diagnosis - This leads to unnecessary medication use and delays identification of the true underlying cause 4

Recognize that 30-50% of dyspnea cases have multifactorial etiologies - After identifying the primary cardiac cause, continue to evaluate for contributing conditions such as anemia, renal dysfunction, or pulmonary disease 5, 6

In patients with known heart failure presenting with acute worsening, actively search for new superimposed pathology such as acute coronary syndrome, pulmonary embolism, pneumonia, or arrhythmia 1

Algorithmic Approach

1. If BNP <100 pg/mL: Heart failure is unlikely; pursue alternative diagnoses (pulmonary disease, anemia, deconditioning) 1

2. If BNP 100-500 pg/mL: Intermediate probability; proceed to echocardiography for definitive evaluation 1

3. If BNP >500 pg/mL: Heart failure highly likely; obtain echocardiography and initiate heart failure management while completing workup 1

4. If echocardiography shows valvular disease: Quantify severity and refer to cardiology for intervention consideration 1

5. If echocardiography shows reduced ejection fraction: Diagnose systolic heart failure and optimize guideline-directed medical therapy 1, 3

6. If echocardiography shows preserved ejection fraction with diastolic dysfunction: Diagnose heart failure with preserved ejection fraction and manage volume status 1

The combination of clinical assessment, BNP measurement, chest X-ray, ECG, and echocardiography will establish the diagnosis in the vast majority of patients presenting with orthopnea. 1