Right. So we’ve discussed the examination,
what you’re looking for, the general reasons
why abnormal signs may occur. But, as a doctor,
what you need to be able to do is have a synthesis
of that: a way of interpreting what information
you have and saying what the pathology may
be that’s causing that.
So, for example, there are very specific signs
which are associated with pneumothorax, pleural
effusions, lobar collapse, lobar consolidation,
bronchiectasis, pulmonary fibrosis which is
the synthesis of all that respiratory examination.
There’s a pattern of abnormalities that
occur that would indicate that that disease
of that process might be present.
Knowing these makes life considerably more
straightforward when you’re trying to interpret
the examination. And what you should be doing
is saying, “Well, okay. There’s dullness
to percussion at the right base. That suggests
the patient may have a pleural effusion. So
there should be absent breath sounds down
there. And if there’s absent breath sounds,
that helps. That confirms that there might
be an effusion. However, in an effusion the
trachea should be deviated away but not towards
the side where you’re hearing the dullness
to percussion. And if the trachea is deviated
towards that side, then that suggests in fact
that it’s not an effusion but it may be
a collapse instead. So it’s the combination,
the constellation of these signs which makes
the diagnosis of what the pathological process
might be relevant.
Right. So just going through some of these
processes in more detail.
The signs for a pneumothorax: the trachea
will be deviated away from the affected side.
There’ll be reduced expansion on the affected
side. And that will be detectable because
the normal side will be moving fine. The percussion
will be resonant and in fact should be hyper-resonant
but, as I said, it’s quite hard to detect
that. When you listen over a pneumothorax,
you should hear no breath sounds. Vocal resonance
should be reduced as well. And the extent
of that depends on the size of the pneumothorax.
If there’s a small pneumothorax, you’ll
just hear that at the top of the lung. If
it’s a very large pneumothorax, you’ll
hear it throughout the lung. There may be
some evidence of the underlying cause for
a pneumothorax and, to be honest, most patients
there’s no underlying cause of primary pneumothoraxes.
However, they could have Marfan’s syndrome,
which would make them very tall with a very
large, wide arm span and very, very flexible
joints. Or they could have a pre-existing
lung disease. Cystic fibrosis, for example,
can cause pneumothoraxes.
Pleural effusions: that’s fluid in the pleural
space as opposed to air, which is a pneumothorax.
It has relatively similar signs to a pneumothorax
in that you have absent breath sounds, absent
vocal resonance, decreased expansion on the
affected side. But it’s fluid, not air.
So, when you percuss, it will be stony dull.
Also the fluid forms at the bottom of the
lung due to gravity and therefore the changes
are best detected at the bases of the lungs.
Occasionally, at the top of a pleural effusion
you might get a pleural rub and some bronchial
breathing. There could be evidence of the
underlying cause of the effusion. For example,
the JVP may be higher because they’ve got
cardiac failure. They may have peripheral
oedema because, again, because they’ve got
cardiac failure. Or you might palpate some
lymph nodes suggesting they might have a cancer
or something similar along the similar lines.
The trachea is also going to be deviated by
large pleural effusions. But, unlike a pneumothorax,
it has to be quite a large pleural effusion
before it will shift the trachea across to
the other side.
Lobar collapse is where a bronchus has been
obstructed and, as I mentioned earlier, the
air distal to that area has been resorbed
making the lobe collapse down into a solid
area. And that could be a right main bronchus,
a left main bronchus, the right upper lobe
bronchus, the right intermediate bronchus,
the left upper lobe, the left lower lobe.
And so you have different patterns depending
on which lobe has been obstructed. They all
cause the same constellation of symptoms which
is first of all, unlike what this sign – this
slide says, the trachea is deviated towards
the affected side. So that’s because of
the volume loss of the collapse. It pulls
the trachea and the mediastinum across to
the affected side. There’ll be reduced expansion,
dull percussion note, absent breath sounds,
absent vocal resonance. And those are all
signs which are very similar to a pleural
effusion. So the confusion between a pleural
effusion and lobar collapse is very easy clinically.
And it’s the trachea that gives you the
clue that there is a problem with collapse
rather than fluid.
Lobar consolidation: this is largely pneumonia.
Not always, but most cases of consolidation
are due to pneumonia. In this situation, what’s
happened is the alveoli, instead of being
filled with air, are now filled with an inflammatory
exudate – white cells, bacteria. And therefore
the volume hasn’t changed so the trachea
stays central and the mediastinum doesn’t
shift. But the affected area, if it’s large
enough, will be detectable by the expansion
being reduced on the affected side. There’ll
be dullness to percussion over the consolidated
lobe. Breath sounds though will actually increase.
This is where you get the bronchial breathing.
There’s increased intensity of the breath
sounds: bronchial breathing. And over the
affected lung you could get coarse crepitations.
And unlike other causes of chronic crepitations,
pneumonia is normally a bit asymmetric in
its distribution. There’ll be one lung with
quite extensive consolidation. The other lung
may have some or may have none at all. And
that means the crackles themselves will be
asymmetric in distribution.