Cardiac Tamponade - Diagnosis

Diagnosis

Initial diagnosis can be challenging, as there are a number of differential diagnoses, including tension pneumothorax, and acute heart failure. In a trauma patient presenting with PEA (pulseless electrical activity) in the absence of hypovolemia and tension pneumothorax, the most likely diagnosis is cardiac tamponade.

Signs of classical cardiac tamponade include three signs, known as Beck's triad. Hypotension occurs because of decreased stroke volume, jugular-venous distension due to impaired venous return to the heart, and muffled heart sounds due to fluid inside the pericardium.

Other signs of tamponade include pulsus paradoxus (a drop of at least 10mmHg in arterial blood pressure on inspiration), and ST segment changes on the electrocardiogram, which may also show low voltage QRS complexes, as well as general signs & symptoms of shock (such as tachycardia, breathlessness and decreasing level of consciousness).

Tamponade can often be diagnosed radiographically, if time allows. Echocardiography, which is the diagnostic test of choice**, often demonstrates an enlarged pericardium or collapsed ventricles, and a chest x-ray of a large cardiac tamponade will show a large, globular heart.