Which of the following clinical signs may occur with a large pleural effusion?I. Reduced chest expansion on the diseased sideII. Reduced breath sounds on the diseased sideIII Tracheal deviation AWAY from the diseased sideIV. Dull percussion note over the diseased side

A large pleural effusion refers to the build-up of excess fluid between the layers of the pleura outside the lungs. It can lead to various clinical signs:

I. Reduced chest expansion on the diseased side: This is likely to occur because the excess fluid in the pleural space can restrict the expansion of the lungs, leading to reduced chest expansion on the affected side.

II. Reduced breath sounds on the diseased side: This is also likely to occur. The fluid in the pleural space can act as a barrier to sound transmission, leading to reduced breath sounds when listening with a stethoscope.

III. Tracheal deviation AWAY from the diseased side: This may occur in large pleural effusions. The build-up of fluid can push the mediastinum (the central compartment of the thoracic cavity) away from the affected side, causing the trachea to deviate away from the diseased side.

IV. Dull percussion note over the diseased side: This is likely to occur. When percussing (tapping) the chest wall, a dull note is often heard over areas where there is fluid in the pleural space.

So, all of the clinical signs listed (I, II, III, IV) may occur with a large pleural effusion.