00:01
So how do we assess ventilation?
Ventilation can be assessed
using several
respiratory volumes.
00:09
These respiratory volumes
can then be combined
in order to calculate something
called respiratory capacities.
00:16
It is these capacities
which give us information about
a person's respiratory status.
00:23
Respiratory volumes
and capacities are usually
abnormal and people
with certain pulmonary disorders
and the instrument that
we use to measure this
is known as a spirometer.
00:35
Now the olds spirometer
were pretty clunky
and cumbersome to use
but now mostly spirometer
are used electronically.
00:45
So first, let's start with
our respiratory volumes
because these are going to
be important in determining
our respiratory capacities.
00:52
There are four main
respiratory volumes.
00:55
We have the title volume,
which is just the amount of air
moving in and out of the
lungs in a normal breath.
01:02
This is usually about
500 milliliters.
01:06
Then we have our
inspiratory reserve volume.
01:09
This is the amount of air
that can be inspired forcibly
beyond the title volume.
01:15
So for example,
if your doctor were to tell
you to take a deep breath.
01:20
Opposite to this we have our
expiratory reserve volume.
01:24
This is the amount of air
that can be forcibly
expelled from the lungs.
01:29
For example,
if the doctor were to tell
you to take a deep breath out
and then we have
our residual volume.
01:37
This is the amount of air
that always remains
in the lungs.
01:41
The lungs are never
completely empty,
And the reason why is
because we need to keep our
alveoli inflated or open,
so there's always a
residual amount of air
in the lungs at all times.
01:55
So we combined these volumes
in order to determine different
capacities of the lungs.
02:01
To determine our
inspiratory capacity,
w e look at the sum
of our tidal volume
and our inspiratory
reserve volume.
02:11
In order to determine our
functional residual capacity.
02:15
We look at the residual volume
as well as the expiratory
reserve volume.
02:22
We determine the vital
capacity of the lung
by looking at our title volume
and adding it to our
inspiratory reserve volume
and our expiratory
reserve volume.
02:35
And finally our
total lung capacity
as a sum of all four
of the different
respiratory volumes.
02:46
So this is also depicted
here in this chart
and it says exactly
what I said before
where are four total volumes
can be used to determine
different types of capacity.
02:59
So volumes and capacities are
going to be a little different
between males and females.
03:04
So while the title volume
is generally the
same for all adults
whether male or female
the other volumes and
subsequent capacities
are usually lower and females
than they are in males.
03:21
So another component
of the lungs
is also the
anatomical dead space
or just dead space in general.
03:27
And are anatomical dead space,
this is not going to
contribute to our gas exchange
and it's just going
to consist of air
that is kind of always sitting
in the lungs at all times.
03:39
This is usually about a
hundred and fifty milliliters
out of the 500
milliliters of air
that we take in and out
or our title volume.
03:48
We also have a dead space known
as the alveolar dead space
and in this space,
it is occupied by
non-functional alveoli.
03:57
These usually occur due to
a collapse of the alveoli
or some type of obstruction.
04:04
The total dead space is
going to be the total of
the anatomical
and the alveolar dead
space in the lungs.