Position of mediastinum gives important clues to the nature of
process in each hemithorax. Trachea is the index of upper mediastinum and heart of the
lower mediastinum.
Method of Exam
Examine the position of mediastinum by standing in front of the patient. Make
certain that the patient is seated straight or preferably standing erect. Trachea is the
index of upper mediastinum. Heart is the index of lower mediastinum. Position of the heart
can be used as an index of mediastinum only when it is not enlarged.
- Inspect for the symmetry of clavicular insertion of
both sternomastoids.
- Tracheal Position: Gently bend the head to
relax sternomastoids. Assess and compare the space between the trachea and sternomastoid
on either side. Keep the tips of your index and ring fingers over the medial end of the
clavicles. Then, with the middle finger, assess the space between the trachea and
sternomastoid.
Caution: Make sure that your nails are trimmed.
- Position of Heart: Identify the
location of apex of the heart by inspection and palpation.
Caution: Make sure that the heart is not enlarged.
Normal
The right sternomastoid is slightly prominent normally. The trachea is slanted
to the right. The apex of the heart is located on the 5th LIC space just internal to the
midclavicular line.
Abnormal
Any deviation of the mediastinum is abnormal.
The mediastinum can be either pulled or pushed away from the lesion.
- Pull: Loss of lung volume (Atelectasis, fibrosis,
agenesis, surgical resection, pleural fibrosis)
- Push: Space occupying lesions (pleural effusion,
pneumothorax, large mass lesions)
- Mediastinal masses and thyroid tumors
- Kypho-scoliosis
Example:
Let us suppose that you have arrived at a decision that the mediastinum is shifted to
left. It could be either due to a pushing lesion from right or a pulling lesion from left.
The next step will help us identify which side is abnormal.
Caution :
- Do not misinterpret apical impulse to mean deviated mediastinum in the presence
of an enlarged Heart.
- Difficult to interpret mediastinal position in a patient with Kypho-scoliosis.
