From the Guidelines
Diagnosing pulmonary edema requires a comprehensive approach that includes clinical evaluation, imaging, and laboratory tests, with a focus on identifying the underlying cause and assessing the severity of the condition, as recommended by the most recent guidelines 1. The diagnosis typically begins with a thorough medical history and physical examination, looking for symptoms like shortness of breath, coughing up pink frothy sputum, difficulty breathing when lying flat, and physical signs such as crackles when listening to the lungs with a stethoscope.
- Key symptoms to look for include:
- Dyspnea (dyspnea with exertion, dyspnea at rest, orthopnea, paroxysmal nocturnal dyspnea, nocturnal cough in supine position, tachypnea)
- Decreased exercise tolerance
- Fatigue
- Worsened end-organ perfusion
- Other symptoms of volume overload
- Physical examination findings considered to be due to heart failure include:
- Peripheral edema
- Increasing abdominal distention or ascites
- Pulmonary rales/crackles/crepitations
- Increased jugular venous pressure and/or hepatojugular reflux
- S3 gallop Chest X-rays are essential and typically show fluid in the lungs, appearing as increased opacity in the lower lung fields, Kerley B lines, and sometimes pleural effusions.
- Additional diagnostic tools include:
- Echocardiography to assess heart function and identify potential cardiac causes
- Blood tests such as BNP (B-type natriuretic peptide) or NT-proBNP which are elevated in heart failure
- Arterial blood gases to evaluate oxygen levels
- Pulse oximetry to measure blood oxygen saturation
- Point-of-care lung ultrasound to evaluate B-lines, as recommended by international evidence-based recommendations 1 In some cases, pulmonary artery catheterization may be performed to measure pressures within the heart and lungs.
- CT scans can provide more detailed images when the diagnosis remains unclear, and may show radiological evidence of pulmonary congestion, such as pulmonary venous or alveolar congestion, interstitial or pulmonary edema, pleural effusion, or cephalization of venous flow 1. The combination of these approaches helps differentiate pulmonary edema from other conditions with similar symptoms and determine whether it's cardiogenic (caused by heart problems) or non-cardiogenic (resulting from direct lung injury), and guides the initial diagnostic evaluation, as outlined in the guidelines for the evaluation and management of heart failure 1.
From the Research
Diagnosis of Pulmonary Edema
To diagnose pulmonary edema, the following methods can be used:
- History taking and physical examination to identify symptoms and signs such as low-flow state, S3 gallop, jugular venous distention, and fine crepitant rales with auscultation 2
- Electrocardiogram (ECG) to assess cardiac function 2
- Chest X-ray to visualize lung fields and detect signs of pulmonary edema 2, 3
- Echocardiography to evaluate left ventricular function and detect signs of cardiogenic pulmonary edema 2, 4
- Laboratory tests, including blood gas analysis to assess oxygenation and ventilation 5, 4
- Specific biomarkers to differentiate between cardiogenic and non-cardiogenic pulmonary edema 2
Bedside Modalities for Diagnosis
Several bedside modalities can be used to diagnose pulmonary edema, including:
- Chest auscultation to detect crackles and other abnormal sounds 3, 6
- Lung ultrasonography to detect B-lines and pleural effusions 3, 4
- Transpulmonary thermodilution to measure extravascular lung water accumulation 3
- Critical care ultrasonography (CCUS) to differentiate between cardiogenic pulmonary edema, acute respiratory distress syndrome (ARDS), and other causes of acute hypoxemic respiratory failure 4
Importance of Early Diagnosis
Early diagnosis and treatment of pulmonary edema are crucial to improve patient outcomes 2, 3, 5. Delayed diagnosis and treatment can lead to increased morbidity and mortality. Therefore, it is essential to use a combination of clinical assessment, laboratory tests, and bedside modalities to diagnose pulmonary edema promptly and accurately.