How can you differentiate a pericardial rub from a pleural rub?

A pericardial rub is typically associated with inflammation of the pericardium and produces a sound that is usually heard best with the patient sitting up and leaning forward. Importantly, a pericardial rub remains audible regardless of the patient's breathing pattern, as it is generated by the movement of the heart's surface against the pericardium.

Asking the patient to hold their breath helps in discerning this sound. When a patient holds their breath, a pleural rub—a sound caused by the movement of the visceral and parietal pleura against each other—will become less pronounced or may completely disappear, as it is dependent on respiration. In contrast, the pericardial rub will still be heard even when breath is held, making this method effective for differentiation.

Other methods, such as having the patient cough, change positions, or breathe deeply, do not provide the same clarity in distinguishing between a pericardial and pleural rub. Coughing or changing positions might temporarily alter the sounds of either of the conditions, but they do not consistently demonstrate the persistence of the pericardial rub compared to a pleural rub during breath suspension. Thus, having the patient hold their breath is the most effective technique