How can pneumothorax be differentiated from hemothorax during physical examination?

The differentiation of pneumothorax from hemothorax during a physical examination is primarily based on the sound produced upon percussion of the chest. In pneumothorax, the presence of air in the pleural space leads to a hyperresonant or tympanic sound when the chest is percussed. This occurs because the air-filled space enhances the resonance.

Conversely, in the case of hemothorax, where blood accumulates in the pleural space, the percussion note tends to be dull. This dullness arises because the liquid nature of blood does not resonate in the same way as air does, resulting in a sound that is lower in pitch and less resonant.

Thus, tympanic percussion indicates pneumothorax, while dull percussion indicates hemothorax, making this option the correct way to distinguish between the two conditions during a physical examination.