There is a form of pneumothorax which is a
medical emergency, and this is called a tension
pneumothorax. In this, small hole in the visceral
pleura allows air out when the patient breathes
in. So the pleural space expands with air.
But when the patient breathes out, the hole
is closed down and therefore, the air doesn’t
leave the pleural space, and essentially,
the patient with every inspiration is pumping
out the pleural space with more and more air.
That means that the pneumothorax is under
high pressure and that causes a substantial
shift of the lung and the mediastinum away
from the side which has been affected by the
pneumothorax. And that affects cardiovascular
function, because now, it becomes difficult
for the venous return to the heart to supply
blood to the heart because of the increased
pressure in the system. That means the patient
will present with hypertension, and this is
an incredibly dangerous situation that requires
very rapid treatment.
So, how do you recognize somebody with a tension
pneumothorax? Well, first of all, they’ll
be in severe respiratory distress, they’ll
have low blood pressure, every time they sit
up, they will be fainting potentially, and
there’s marked tracheal deviation when you
examine them. The chest X-ray will show an
obvious pneumothorax, excessive mediastinum
shift, and the diaphragm, instead of being dome
shape will be flattened, and that represents
the pressure that is present in the pleural
space in a tension pneumothorax pushing the
diaphragm down, and an extreme surface dense
of the diaphragm will be inverted.
Treatment is very simple and very obvious.
All you need to do is equalize the pressure
in the pleural space with atmospheric pressure.
And to do that, you just need to make a hole.
So a rapid treatment is insertion of a wide
bore cannula in the second intercostal space
in the midclavicular line. That’s chosen
as a relatively safe place to put a needle
the air is likely to be most marked at the top
of the lung. If you put the needle in there,
you’d equalize the pressure between the
pleural space and atmosphere and the tension
pneumothorax problem resolves. It doesn’t
resolve the pneumothorax, but it resolves
the problems of the pressure, and the patient
will then need to have a chest drain inserted
after that. So, the next section of the
talk is about
bacterial infection and pleural effusions.
I’m not going to talk about tuberculosis
then. This is all about pyrogenic bacterial infections.
So I mentioned before
pleural effusions often occur in patients
who’ve had pneumonia. And those initially
are called simple para pneumonic effusions. They occur
in about 30% of people with pneumonia,
and those represent areas of information overlying
the area of consolidation in the lung with pneumonia
with a small amount of fluid formation, but
the fluid is sterile. The bacteria have not
translocated across from the lung to infect
that pleural space. And these small sterile
effusions are not really necessarily to
However, in some patients, that small sterile
effusion gets bacteria into it and then it
becomes what we call a complex para pneumonic
effusion. They tend to be bigger in size.
They get adhesions between the visceral and
parietal pleura and there is bacteria identifiable
in the pleural fluid. And these patients do
need to have that pleural space drained and
prolonged antibiotics to ensure they don’t
develop the last step which is an empyema
where they have frankly purulent pleural fluid.
This is a chest X-ray which shows somebody
with a loculated pleural fluid of that right
lung. Previously, they just had right lower
lobe pneumonia and this is the development
of empyema as a consequence of a parapneumonic
effusion that has become infected.