Which sign is most indicative of a severe pleural effusion?

Dullness to percussion is a key physical exam finding indicative of a severe pleural effusion. When there is a significant accumulation of fluid in the pleural space, the normally resonant sound produced by percussing the chest will change to a dull sound over the area where the fluid has pooled. This is due to the density of the fluid compared to air-filled lung tissue.

In cases of pleural effusion, as the volume of fluid increases, the dullness becomes more pronounced, effectively reflecting the severity of the condition. Recognizing dullness to percussion allows healthcare providers to identify and assess the extent of pleural effusions, potentially guiding further diagnostic and therapeutic interventions.

Other signs may indicate different conditions or less severe effusions, which is why they are not as definitive in indicating a severe pleural effusion. For example, increased breath sounds are often heard in the case of lung consolidation or a more limited effusion, while hyper-resonance might suggest pneumothorax rather than fluid accumulation. Symmetrical chest expansion indicates normal lung movement and does not provide specific information about fluid presence.