00:00
Acute exacerbations
of asthma. This is a common
cause of medical admissions or presentation
to the action to merge and then being
discharged back home again and most doctors need
to know how to deal with this. The patient
usually knows they have asthma. The attack
itself often comes on over minutes or a few
hours. But it’s usually preceded by a few
days where the patient has a deteriorating
control of their asthma with increased breathlessness,
increased cough, increased nocturnal symptoms,
and increased use of their beta2 agonist
rescued medication.
00:39
So this is important because that preceding
few days with correct education of the patient
and a treatment plan allows you to pre-empt
the potential exacerbation in many patients.
00:51
And if that deterioration and control is treated
effectively by an increased use of the inhalers,
increased corticosteroids, perhaps a quart
of oral prednisolone, then many exacerbations
could be prevented. And the patient may not
need to end up in hospital.
01:06
There’s often actual trigger for this. The patient
had a cold or flu recently. They’ve gone
through particular form of stress. And occasionally,
acute attacks might occur because of smoke
exposure. In the old days when people used
to smoking pubs, occasionally, asthma attacks
would occur because an asthmatic has gone
into particularly smoky pub, for example.
01:26
And we have these situations occur occasionally
during summer when there’s been a thunderstorm
and the release of fungal spores actually
precipitates a large number of acute exacerbations
of asthma over the next few hours.
The patient presents with basically exaggerated
version of the normal symptoms of asthma which
is breathlessness, wheeze, and cough, with
breathlessness being dominant and the main
reason why they’re coming to a hospital.
01:51
And when you listen to their chest, there will
be a polyphonic expiratory wheeze throughout
both lungs. And importantly, their peak flow,
the measure of the airways obstruction, when
you repeat it in casualty, will be lower than
it should be normally.
02:04
So, it’s very important for the patient to
be able to tell you what their normal peak
flow is when they are well so you can compare
during an exacerbation to give you a feel
for how severe the exacerbation is. In normal
exacerbation, they will be more breathless.
02:21
They’ll be wheezy, and there will be a fall
in peak flow. A more severe exacerbation, then the
patient starts to becoming so breathless
that they can’t talk in complete sentences.
02:31
The pulse rate will be very high above 110.
The respiratory rate will be greater than
25. If you measure their blood pressure, there
will be a fall
in systolic blood pressure and inspiration that’s
called pulsus paradoxcus. And the peak flow,
when you measure it, it would be less than
50% predicted or their previous best result.
02:51
These are indicators of severe disease which
is going to require quite an intense treatment.
02:57
Now, the signs of very severe disease, in
fact, when the pulse rate starts to go down
or the breathing rate starts to go down, then
you should really worry because the patient
is close to respiratory arrest. The same
with the blood pressure that starts to fall
that is clearly showing severe physiological
upset. And if the patient’s conscious level
is fluctuating and drowsy, then again, that’s
a very bad sign indeed that the patient has
a very severe disease.
When you listen to chest in severe asthma,
you may not hear the wheeze. There’s so
little air moving on inspiration that the
breath sounds will be very quiet. And the
peak flow unrecordable will considerably be
low than normal. They are less than 30%
predicted. And when the patient develops
central cyanosis due to hypoxia or a CO2 that
starts to increase, then you know the patient
has bad disease. Normally, carbon dioxide
level, actually falls in mildest attacks of
acute asthma because the hyperventilation
leads to a degree of respiratory alkalosis.
04:05
As the attack becomes more severe, the carbon
dioxide actually becomes normal. So a normal
PaCO2 in somebody presenting an asthma attack
is actually a bad sign. It suggests they have
a very severe level of asthma attack. And
then when it starts to rise, then that really
does show that they’ve got severe hyperventilation
going on and they are in danger of a respiratory
arrest. The treatment for asthma exacerbations
is relatively straightforward; high flow oxygen,
nebulized bronchodilators, salbutamol and
ipratropium, an immediate stat dose of intravenous
high-dose corticosteroids. And then if there’s
no immediate response to a nebulised bronchodilators
with rapid improvements in peak flow in the
patient’s condition, then you may want to
consider intravenous bronchodilators. The
commonest being used nowadays is magnesium.
04:58
Once you’re doing this, you need to organize
a chest X-ray, and the chest X-ray is important
not because it’s going to be abnormal in
somebody with asthma but to make sure that
when you’re examining the patient, you haven’t
missed something like a pneumothorax or a
lober collapse which will contribute towards
why the patient is feeling so bad. And clearly,
a pneumothorax can be corrected very rapidly
by insertion of a chest drain. It’s a very
important thing not to miss. You’ll also
measure the peak flow and get
the blood gases. So you have the levels available
to monitor their improvements, or you have
the levels available to identify the severity
of the diseases that we discussed a slide or two ago. And also, so
that you can monitor if the patient is improving
with the medication that you’re giving.
05:41
And you monitor using oxygen saturations,
the pulse rate, the respiratory rate, and
repeating the peak flow. And if the patient
is not responding and it’s doing badly with
very low peak flows, low conscious level,
despite all that medication, then there should
be no delay in intubation and mechanical ventilation
of the patient to take over the work of breathing
for them, because otherwise, there is a risk
of cardiac respiratory arrest, and then there’s
a very high chance the patient would die.
And there are over a thousand deaths each
year in the U.K. due to asthma, and a lot
of those have been shown to be avoidable if
more effective treatment was initiated, or more
importantly, the exacerbation was pre-empted
by effective treatment a few days before they
present to the hospital.