What is the diagnosis and treatment for a patient presenting with orthopnea, fever, and leg pain?

Differential Diagnosis and Management of Orthopnea, Fever, and Leg Pain

Most Likely Diagnosis: Acute Decompensated Heart Failure with Concurrent Infection

The combination of orthopnea and bilateral leg swelling strongly suggests acute heart failure, while fever indicates a precipitating infectious process that requires urgent identification and treatment. 1, 2

Critical Initial Assessment

Immediate Life-Threatening Conditions to Exclude

• Pulmonary embolism must be ruled out first, as it presents with dyspnea, tachycardia, fever (≥38°C in some cases), and leg pain/swelling from deep venous thrombosis 1, 2
• Acute coronary syndrome can precipitate heart failure decompensation and may present atypically with dyspnea rather than chest pain 2
• Pneumonia with heart failure is a common combination, presenting with fever, productive cough, localized pleuritic pain, and regional dullness to percussion 2
• Acute pulmonary edema requires immediate recognition based on respiratory rate >25 breaths/min, oxygen saturation <90%, bilateral pulmonary rales, and orthopnea 1

Clinical Classification of Heart Failure

The patient should be classified as "warm and wet" (well-perfused and congested) based on the presence of orthopnea and leg swelling without signs of hypoperfusion (cold extremities, oliguria, mental confusion, narrow pulse pressure) 1

Diagnostic Workup

Immediate Testing (Within 10 Minutes)

• ECG to identify acute coronary syndrome, arrhythmias (rapid atrial fibrillation, bradycardia <40 bpm), or signs of pulmonary embolism 1, 2
• Vital signs including respiratory rate (>25/min indicates respiratory distress), oxygen saturation (<90% requires supplemental oxygen), heart rate (>120 bpm indicates tachycardia), and blood pressure 1

Essential Laboratory Tests

• Cardiac troponin measured immediately to exclude myocardial infarction as precipitant 2
• Complete blood count with differential to assess for infection (elevated white blood cells) and anemia 1
• Serum creatinine and electrolytes to evaluate renal function and guide diuretic therapy 1
• Blood lactate if hypoperfusion suspected (>2 mmol/L indicates tissue hypoxia) 1
• Blood cultures before antibiotic administration if fever present 1

Imaging Studies

• Chest radiograph to confirm pulmonary congestion, identify pneumonia, assess for pleural effusion, or detect pneumothorax 1, 2
• Echocardiography to assess left ventricular ejection fraction, valve function, and pericardial effusion 1
• Leg vein imaging (compression ultrasound) as first-line investigation given clinical suspicion of deep venous thrombosis with leg pain and swelling 1

Risk Stratification for Pulmonary Embolism

If immobilization in past 4 weeks, history of DVT/PE, or malignancy present, pulmonary embolism probability is elevated and requires further investigation 1

Treatment Algorithm

Step 1: Oxygen and Respiratory Support

• Supplemental oxygen if SpO₂ <90% or PaO₂ <60 mmHg, starting with 40-60% oxygen titrated to SpO₂ >90% 1
• Non-invasive ventilation (CPAP or BiPAP) if respiratory rate >25/min with accessory muscle use despite oxygen therapy 1

Step 2: Immediate Pharmacologic Management for Heart Failure

• Intravenous loop diuretic (furosemide 40-60 mg IV, or 2.5 times existing oral dose if already taking diuretics) to reduce congestion 1
• Target urine output >100 mL/hour in first 2 hours; if inadequate response, double the diuretic dose up to furosemide 500 mg by infusion over 4 hours 1
• Intravenous vasodilators (nitroglycerin starting at 10 μg/min, doubled every 10 minutes based on blood pressure response) if systolic BP >110 mmHg 1

Step 3: Identify and Treat Precipitating Infection

• Empiric antibiotics should be started immediately if pneumonia suspected based on fever, productive cough, and chest radiograph findings 1
• Preferred antibiotic for community-acquired pneumonia: amoxicillin or macrolide in primary care; consider broader coverage if hospitalized 1
• Fever ≥38°C (≥100.4°F) makes pulmonary embolism less likely but does not exclude it 1

Step 4: Anticoagulation Decision

• Start heparin immediately if high or intermediate clinical suspicion for pulmonary embolism before diagnostic confirmation 1
• Continue heparin until maintenance warfarin achieved (INR 2-3) 1
• If pulmonary embolism confirmed with hemodynamic instability (systolic BP <90 mmHg), thrombolytic therapy is indicated 1

Monitoring and Response Assessment

Expected Response Within 1-2 Hours

• Reduction in dyspnea and respiratory rate 1
• Adequate diuresis (>100 mL/hour urine output) 1
• Increase in oxygen saturation if initially hypoxemic 1
• Improvement in skin perfusion (warmer extremities, better color) 1

Signs of Inadequate Response Requiring Escalation

• Persistent respiratory distress despite oxygen and diuretics 1
• Urine output <100 mL/hour after initial diuretic dose 1
• Worsening hypoxemia or increasing confusion 1
• Development of hypotension (systolic BP <90 mmHg) indicating cardiogenic shock 1

Critical Pitfalls to Avoid

• Do not assume orthopnea alone confirms heart failure—pulmonary embolism can present with dyspnea and leg swelling without classic pleuritic chest pain 1
• Do not delay anticoagulation if pulmonary embolism probability is high or intermediate; start heparin before imaging confirmation 1
• Do not attribute all symptoms to heart failure when fever is present—actively search for and treat precipitating infections 1
• Do not use excessive diuretic doses initially without assessing response; start with appropriate dose and titrate based on urine output 1
• Do not overlook alternative diagnoses such as acute coronary syndrome, which can present with dyspnea rather than chest pain, particularly in elderly patients, women, and those with diabetes 2

Disposition and Follow-Up

Patients with persistent orthopnea despite treatment have significantly higher hospitalization rates (64% vs 15.3%) and worse left ventricular function outcomes, requiring more aggressive management 3