00:00
worse asthma. And this is a major driver for many
patients conditions. So, we can characterize
asthma into various different subtypes as
well. Chronic asthma, this is when you’ve
developed an element of irreversible disease
leading to chronic dyspnoea or a chronically
low FEV1, and reflects poorly controlled disease
over many years.
00:18
An exacerbation, that’s an acute deterioration
stimulated often by the triggers we’ve just
discussed. A severe asthma is an attack of
asthma that’s bad enough to require admission
to hospitals. So as in exacerbation, they
require somebody to come into the hospital.
00:34
Status asthmaticus is one level above that
where you have an exacerbation which is severe
enough to be life-threatening and requires
very close attention to treatment to ensure
that the patient gets better. And there is
not an instant response. It’s not with a
less severe exacerbation. One dose of nebulizer
is probably normal enough to restore them
to reasonable health. In the status asthmaticus,
it requires much
more intense treatment there. Doctors often
use the phrase bronchospasm, and all they
mean by that is an episode of increased bronchial
obstruction or an increased episode of airways
obstruction, and that essentially is an exacerbation.
Other subtypes of asthma include brittle asthma.
01:20
These are patients who actually are relatively
well most of the time but then can have sudden
exacerbations which can be very rapidly developing.
I have a patient who went down into the kitchen
one day feeling perfectly well, and next time
she woke up, she was in hospital
intensive care. And what had happened is that
somewhere in the kitchen, something had set
off her asthma attack. And fortunately, the
postman found her when he came to deliver a parcel
that day. Otherwise she would have been dead.
That’s brittle asthma, very rapid attacks,
rapid falls in peak flow, very severe, and because
of that, very dangerous disease. Difficult
asthma is a range of problems. It’s when
the asthma is poorly controlled and causing
major symptoms for the patient or frequent
admissions to hospital. It’s defined as
difficult asthma when it’s poorly controlled
despite extensive treatment and there are a variety
of reasons why that might be not responding
to the treatment.
02:14
Steroid-resistant asthma is a subtype of difficult
asthma which is very specific. It’s where
steroids which normally work very well in
asthma are not working. The type of information
that patient’s asthma is due to does not
respond to corticosteroid therapy for whatever
reason. Cough-variant asthma is essentially
very mild asthma where the only symptom the
patient has is cough, and this one is quite
hard to diagnose because there’s no wheeze
and breathlessness and patients don’t think
that the cough could be due to asthma and
nor to their doctors either. Occupational asthma,
we’ve already discussed,
that’s asthma that’s settled by inhaled
allergens that you come across during your
occupation. It’s very important to identify
because clearly, the patients would need to change
their job circumstances, either change their
job or make sure they have protective equipment
when they’re doing their job to try and
minimize the disease problems.
03:08
So, how do you make a diagnosis of asthma?
Essentially, we need to prove the reversible
airways obstruction. Now as I mentioned, clinically,
that may be obvious in some patients, and
therefore, the requirements to prove that
it’s present is not so important. But it
can be proved in other ways. One is by response
to treatment. If somebody comes to you with
episodes of cough and breathlessness and wheeze
and these sounds very much like they have
asthma, perhaps, this diurnal variation is
worse in the morning, the cough wakes them
at night. Every time they get a cold, it’s
made worse.
03:42
Those sorts of patients, you probably don’t
actually need to do too much besides give
them the right treatment. And if they get
better, then that’s asthma. If you really
want to prove it’s asthma, peak flow recordings
are a good way of doing that. Now, these record
the airflow during expiration, and they show
diurnal variation in asthmatics. So for example,
in this chart you see on the right-hand side
of the slide, there's a big fall in the peak
flow in the morning. Now, when you start to
inhale steroid, what happens is that the peak
flow will gradually improve as the asthma
comes under control, but not only that is
at the difference between the morning and
evening, the diurnal variation becomes smaller.
04:24
So the home peak flow recordings, with and without
treatment, are a very good way of identifying
patients who have asthma for sure. And you
can also use spirometry, the FEV1, and I showed
that in a spirograph earlier with FEV1 which
improves substantially after bronchodilator
showing significant reversible disease, and
therefore if the patient has asthma.
04:44
Other tests, well, blood tests may show degree
of blood circulation eosinophilia. And then
the patient often has a raised total IgE and
can be allergic to aspergillus, especially
if they have allergic bronchopulmonary aspergillosis
which is a complication of asthma, which are
discussed in a subsequent lecture. The chest
X-ray is necessary to make sure you’re not
missing any other diseases, but essentially,
is normal in most patients of asthma unless
they have an acute attack of chronic severe disease.
In which case, that will show hyperexpanded
lungs. But as I said, a chest X-ray is vital
during exacerbations at least to just make
sure there’s no other complication such
as a lobar collapse or an infection.
05:26
We often do skin prick tests in patients with
asthma, and that’s to identify specific
allergic triggers for allergic asthma, house
dust mites, cat fur, etc. In many ways, it’s
not very practical because if a patient knows
that a cat will upset his or her asthma, then
they avoid cats. It’s only particularly
relevant I suppose for patients where you
might be considering allergic bronchopulmonary
aspergillosis as a diagnosis in which case,
the skin prick test will be positive to aspergillosis.
Occasionally, you might come across a patient
where it’s quite hard to identify they have
asthma. And then we might do things like a histamine
or methacholine challenge tests where the
patient inhales histamine or methacholine
and that causes bronchoconstriction in patients
who have asthma. But it doesn’t in patients
who don’t have asthma. So that’s inducible
airways obstruction. It’s quite a tricky
test. It needs to be done in the hospital
in a fully equipped pulmonary function laboratory
But it can be used to identify difficult
cases of asthma to diagnose. And the sputum
itself may show the evidence of airways information
with the presence of eosinophilia when you
send the sputum off for cytology.
How do you treat asthma? Essentially, it’s