Okay, definition of dyspnoea. What does dyspnoea
mean to you? It means shortness of breath.
What's causing this? Well, it could be two
things. Meaning to say, it could be two pathogenesis.
One, it could be the fact that maybe the patient
does have some type of infection. Maybe some
type of fibrosis has taken place with the
lung itself. Primary lung problem will be
an issue. And with the primary lung problem,
for example if it is emphysema even,
then understand that at this point, the type
of edema that the patient is going to develop
is going to be of pulmonary origin. And if
it is a pulmonary origin such as infections,
such as emphysema, would you tell me the common
denominator in both of these conditions that
are pulmonary? What kind of inflammatory cells
might you be bringing in? Phagocytic cells.
Maybe these are neutrophils. Interesting.
So from immunology, you have had the discussion
of inflammation, haven’t you? And give me
some of those cardinal signs of inflammation
Rubor, calor, tumor, dolor, functio, laesa. Rubor,
calor, tumor, give me those three in Latin.
Rubor, redness, tumor, swelling, calor, heat,
think burning calories, clear? Now, so those
are the three that I am referring to right
now. What does that mean? It means the blood
vessel underwent vasodilatation. What was
my the metabolite? What was responsible for
this vasodilation? Histamine.
What am I trying to get at? When you have
pulmonary type of origin disease or pulmonary
pathology and you have things like emphysema
with smoking and you also have issue such
as infections, then understand that they have
increased capillary permeability. Interesting.
So, if you have increased capillary permeability,
is it possible that you might get protein
into your interstitium? Sure. It is protein
rich. Good. So therefore, what kind of edema?
Exudate. Good. What if there was a type of
pulmonary edema that was cardiogenic. Are
we clear now? If it's cardiogenic, left-sided
heart failure, clear? Back up,
left ventricle, left atrium, pulmonary
veins what you have increased? Hydrostatic
pressure. What is this? Protein poor. So, you have a
type of edema that is transudate. So, as you
know, pulmonary edema could result in a dyspnoea,
but there are many issues or many
etiologies of dyspnoea. I have just given
you some common ones that you want to keep
in mind with edema being a cause of dyspnoea.
So, with the shortness of breath, what happens?
Well, now, once again, you want to be familiar
with terminology. We are going to hold on
to carbon dioxide. And so therefore, this
is referred to, now the same thing. Some of
you might have heard of this being capnia
and some of you might have heard of it as
being carbia. For all intent and purposes,
you as a clinician, will be using this interchangeably.
So, if you have a dyspnoea, and then maybe
perhaps you are holding onto carbon dioxide?
Sure, you are not blowing it off, are
you? Good. If you are going to increase carbon
dioxide in your plasma, then what
is this called clinically? Respiratory acidosis.
This is called hypercarbia. Go one step further,
from physio, give me the average carbon dioxide
in its normal level. You can use 40, you are
in good shape. Okay. 40 is normal. So you tell
me, the patient is not breathing properly.
He is not blowing off carbon dioxide. Clinically,
we describe this being hypercarbia, which
means that your carbon dioxide levels have
increased. Maintain composure at all times,
it's a lot of information. And it's just a nice
little story line that always takes place.
Respiratory acidosis, dyspnoea. What else?
Well, maybe if there is dyspnoea, could there
be hypoxia? In fact, by definition,
when you have respiratory failure, there are
two types. Type 1 or type 2. Type 1 or type
2 will both have a decreased in oxygen, hypoxia.
Not good. And the magic number that you want
to know here for partial pressure of oxygen
is 60 mmHg. Really? May I ask you something?
Would you please tell me what the normal amount
of oxygen should be with partial pressure
in the systemic arteries? What is a systemic
artery? Give yourself one big example. Aorta.
What is your PaO2 in your aorta? PO2 of 100,
correct? So, by the time you go into the venous
side, what is your PO2? Your PO2 has now dropped
down to approximately 40, hasn’t it? So,
by definition, if you are hypoxic and then
you find your PO2 dropping below 60 mmHg,
just keep in mind maybe hypoxia has set in.
Where? On the arterial side. What is normal?
100. The fact that you are finding 60 on the
arterial side is a problem. I don’t want
you to confuse that. Remember, when you do
an ABG, what’s an ABG? That’s you're responsible
for doing. Arterial blood gas, not venous blood
So you are measuring the oxygen arterial side,
so what's your oxygen there? Should be normally
hovering around 95-100. 60 is a problem. More
commonly, dyspnoea occurs independent of a
gas exchange abnormality. We will talk about
other issues here. Now, the control center.