00:00
Right, so
the next section of this talk is going to
be about acute exacerbations. These are the
commonest cause of admission to hospital in
industrialized countries would be an acute
exacerbation of COPD. And there are some important
questions to answer. The first is, what is
the cause of the exacerbation in this presenting
patient. It could be infective, in which case
they will have purulent phlegm, the sputum
culture might be positive and the CRP might
be slightly raised, maybe not very high,
it may even be only 10 or 15. But that will all
indicate that there is a bacterial infection
of the bronchi precipitating the COPD exacerbation.
Non-infective exacerbations the patient tend
not to produce phlegm, or if they do it would
be white rather than green phlegm. And you
also need to think about potentially other
problems. Patients with COPD are at a risk
of pneumonia, pneumothorax, PE and they often
have cardiac problems as well which might
lead to pulmonary edema. So you do a chest
X-ray in these patients to exclude those potential
differential diagnosis. The second question
is, how severe is the exacerbation? Can the
patient speak in full sentences? What is the
respiratory rate? What is the pulse rate?
Now obviously a high respiratory rate and
a high pulse rate is bad news, but if its
low, just like in asthma, when the patient
respiratory rate starts to become abnormally
low, that is a very bad sign, and indicative
that they do have severe respiratory failure,
as does drowsiness, the patient is not fully
arousable then they have severe disease.
01:26
The oxygen saturations will also be very beneficial,
but the very important question that can only
be answered by doing a blood gas is whether
they have type 1 or type 2 respiratory failure.
01:38
And type 2 respiratory failure with the retain
of the carbon dioxide causing a respiratory
acidosis requires a very specific treatment
with nasal ventilation which I will discuss
in a slide or two. And the last
question, is what is the treatment
ceiling. How far will we go with treatment
with this patient. And the reason why this
question has to be asked is that these patients
have chronic disability, and many of them
when they are coming to hospital with type
2 respiratory failure will be at their best,
not able to walk more than 10 or 20 yards,
and they may have had recurrent admissions
several times over the previous few years.
And these patients may not want to go through
the full process of the intubated and ventilated
if their deterioration is severe enough to
warrant it. So what's the treatment for COPD
exacerbations. You have to bear in mind that
these exacerbations have about a 9% mortality.
Nearly 1 in 10 patients who comes to a hospital
with exacerbation with COPD will die. So this
is an acute problem which has a significant
mortality attached to it. They need
controlled oxygen, and one of the
important points is that you don't need to
aim for high oxygen saturation, you just need
to aim for a safe oxygen saturation. Higher flow oxygen can cause
problems with increasing CO2 retention, as
I will discuss in the physiology lecture.
02:58
Nebulized bronchodilators, salbutamol. Very standard therapy, very easy
to give. You need to do some blood gases to
look for the respiratory acidosis that we
discussed a few seconds ago, and you need
a chest X-ray to make sure that there's no
pneumothorax, lobar collapse and pneumonia
or an alternative diagnosis such as pulmonary
edema. Now, if the patient has
a raised CO2 and they're
acidotic, then the standard therapy would
be to use nasal ventilation, non-invasive
ventilatory support, which I'll discuss in
the next slide or two. You'll also, in patients
presenting with severe exacerbations of COPD,
could consider using intravenous bronchodilators
such as aminophylline. And all patients will
reveal will be given systemic corticosteroids
therapy usually oral prednisolone for 5 days
and as I mentioned earlier that's known to
reduce the duration of the exacerbation by
about a day and day and a half. And if the
patient has an infective cause of COPD, then
you give them antibiotics, so green purulent
phlegm or positive sputum culture, then you
may give them the antibiotics suitable for
that and normally amoxicillin or doxycycline
is adequate therapy for an infective exacerbation
of COPD. So non-invasive ventilatory support.
04:11
Now, this is a treatment for type 2 respiratory failure
with acidosis, usually due to COPD, although
there are other causes of respiratory diseases
that can lead to this as well that would benefit
from nasal ventilation. The consequence of the COPD
being severe is that you're under-ventilating
the lungs and the advantage of the nasal ventilator
is that by providing a positive pressure on
inspiration when the patient takes a breath,
with a little bit of positive pressure on
expiration as well. What you are you doing
is you're increasing the ventilation of the
lung, and that allows assistance to the patient,
that assistance allows their PCO2 to be blown
off to actually be reduced by increasing their
respiratory ventilation. And nasal ventilation
is normally administered using a nasal or
even a full facial mask.
05:08
The clinical trials show that patients with COPD
and exacerbation of the COPD with respiratory
acidosis treated with nasal ventilation, there's
a reduced need for intubation and ventilation
in intensive care using mechanical ventilators.
But, the patient has to be able to tolerate
the mask, has to be co-operative, they can't
have nasal ventilation if they're very drowsy,
very agitated and it's not particularly suitable
for patients with very high respiratory rate.
05:40
And the most important question is that you
need to decide if nasal ventilation is not
working, do you then move forward in intubation
and ventilation, and only a proportion of
patients will be suitable for that next step
for the more invasive treatment. So invasive
ventilation requires intubation, the replacement
of endotracheal tubes through the mouth into
the trachea, paralysis and ventilation using
a mechanical ventilator. The problem with
COPD is that the pre-existing long term respiratory
problems means it's quite difficult to wean
the patient off the ventilators sometimes,
not always, but it can be, can take weeks
in some patients. It's an appropriate maneuver,
appropriate treatment for patients who clearly
have a reason for an exacerbation, a pneumonia
for example, or a pneumothorax which could
be resolved by drainage, etc. But it's less
appropriate for patients without a clearly
obvious reason for a deterioration in that
condition who are chronically disabled and
coming back to hospital on frequent occasions.
So there are factors that affect whether you
might decide where an invasive ventilation
is appropriate or not. It is number one,
the patient's wishes. Many patients with bad
COPD who have been to intensive care do not
wish to go through that again and they will
write advanced directives stating that they
do not want to be ventilated if the situation
warrants it. The level of their disability,
whether their exercise tolerance is so poor
they can only walk a few yards without getting
breathless and having to stop, whether they
are on home oxygen, these are all indicators
of severe disease that the patient is less
likely to come through the experience of a
ventilation by a mechanical ventilator and
be weaned off that effectively. And again,
the stable FEV1 transfer factor will give
you some feel for the severity of the disease.
07:33
And very importantly, if somebody has had
a previous ventilation episode and that can
tell you whether it's easy for them to be
weaned off the ventilator, and therefore it's
suitable to have another ventilation episode
if necessary, or whether it took a prolonged
period of time, so that it can take weeks
and then the patient will be unsuitable to
go through that process again. And then the
patients themselves will probably say, once
they've been through a ventilator episode, they'll
have clear opinions on whether they'd
like to go through that experience again or
not.