Reasoning

Trachea

The trachea may be deviated by being either pushed or pulled over. The normal intra thoracic pressure is negative. Thus when air at atmospheric pressure enters the thoracic cavity, as in the case of pneumothorax, the increased pressure pushes the trachea to the opposite side.

When there is total collapse of a lung, the trachea is pulled over to the affected side.

On the other hand, consolidation of the lung tissue produces no effect on the tracheal position.

Breath Sounds

Normal vesicular breath sounds have an inspiratory component greater that the expiratory component and are continuous throughout.

With chronic obstructive lung disease the expiratory component is prolonged. The same is also the case in asthma where the prolonged expiration due to constricted bronchioles is accompanied by an expiratory wheeze - the opposite to croup where the wheeze is inspiratory.

In cases of bronchial breath sounds, which may be heard over partial collapse or in lung consolidation, inspiratory and expiratory elements are of equal duration with a space between (due to lack of alveolar component).

However where partial collapse is present and the bronchus is obstructed, breath sounds will be absent.

Percussion

The normal percussion note is a reflection of normal aeration of the alveoli. Where the percussion note is increased it indicates a less solid underlying element. This is particularly increased in pneumothorax where air underlies the percussing finger.

The percussion rate will be duller where the underlying tissue is less aerated. This occurs in classical lobar pneumonia where the lung is solid.

An even duller percussion note is present in cases of pleural effusion where the dullness is "stony" in character - a similar note to that obtained by vintners in percussing their barrels to determine the level of air surface/liquid.

Vocal Resonance

As with all other entities vocal resonance may be either increased or decreased as opposed to the normal.

Increased resonance will be present where the underlying tissue is a better conductor of sound than normal lung tissue in the conduction of sound from the bronchi. The classical example is in consolidation of lung tissue where solid is an excellent conductor.

On the other hand, where no underlying lung tissue is present or the alveolar structure is compromised, vocal resonance will be decreased.

This occurs to some degree in partial collapse and more so in total collapse.

In the presence of fluid between the lung and the chest wall, vocal resonance will also be decreased due to the poor conduction quality of fluid.

Vocal resonance is also decreased, if not absent, in the presence of a pneumothorax where the air prevents conduction.