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so the subject of this lecture our
respiratory physiology disorders what
we're going to talk about in this
lecture is type 1 and type 2 respira
failure the differences between them and
how they should be treated a little bit
about respiratory acid-base disorders
and then we're going to move on to talk
about a specific cause of type 1 with
spiritual failure the adult respiratory
distress distress syndrome a RDS and
also type 2 causes a type to restore
affair which affect lung ventilation but
actually the lungs themselves are normal
and that's mainly obstructive sleep
apnea with some discussion of obesity
hyperventilation and chest war and
muscle disease an important point is
that ventilatory diseases which cause
chronic respiratory failure are usually
worse at night with worse physiological
parameters overnight and the first thing
in the morning right so type 1 Rasputia
failure this is respiratory failure with
hypoxia alone normal po2 but a pao2
which is less than 8 no matter what the
inspired oxygen concentration is now
this is often an acute one-off event but
it can also be a complication of chronic
lung diseases largely COPD what's the
treatment well it depends on the course
somebody comes in with pneumonia and
hypoxia as a consequence I warm spirit
Elliot you clearly treat that pneumonia
somebody comes has COPD you treat the
COPD but the discussion that we're going
to have today is really about oxygen and
how we use oxygen in patients with type
1 respira failure and essentially the
problem is how to correct the hypoxia
and we can use as much oxygen as much as
is necessary in these circumstances and
we give the oxygen normally in a
controlled fashion so we know walked
percentage inhaled oxygen the patient is
receiving so we used venturi mask to do
that and they have different percentages
now some examples are given here 28
percent 35 percent 40 percent and
clearly we used a higher percent oxygen
concentrations for patients
more hypoxia if patients are very
hypoxic we may use a rebreathing bag
which allows an oxygen concentration
about 60% to be inhaled by the patient
just using a mask and what we're trying
to do is we're trying to aim for
saturation for above 94% correct the
hypoxia completely but not only that
we'd like to make the patient able to
breathe at a comfortable respiratory
rate because of their maintaining a
saturation of 95% but their breathing at
40 per minute that is not a good
situation that means they're struggling
very hard they will tire and it's quite
likely that they will fail to maintain
their oxygenation if they have to keep
persisting a respiratory rate of 40 per
minute so what do we do if the patient
is remaining hypoxic or has a very high
respiratory rate despite breathing
oxygen from a mask for a rebreathing bag
well there is a non-invasive form of
ventilatory support called the
continuous positive airway pressure CPAP
now this is a face mask that provides a
small amount of additional pressure on
the inhaled air oxygen mix 5 to 15
centimeters of water and it maintains
that through the whole of respiration
both inspiration and expiration and what
this does is actually recruits more
alveolar units that the patient can use
during their respiration it spins open
and recruits more alveolar units during
inspiration and that allows the inhaled
oxygen concentration to maintain a
better arterial oxygen level and this is
a good treatment for isolated type 1
respira failure somebody presenting we
say for example community-acquired
pneumonia or pulmonary edema
where they have ty warm spiritual
failure but no other major organ damage
if this is not adequate if this starts
to work or the starts to fail to work or
the patient becomes tired despite CPAP
therapy then the next step will be
intubation and artificial ventilation
and an intensive care to Poland so one
of the common causes of type one spirit
failure while acutely pneumonia
pulmonary aspiration
pulmonary oedema exacerbations of COPD
in some patients COPD moderately severe
asthma a large pulley embolus and a RDS
which I'll discuss in later slides
chronically patients can have type one
spirit failure due to institutional lung
disease if it's severe enough if they've
had chronic pulmonary emboli leading to
a significant pulmonary artery damage
then they'll have type 1 spiritual
failure as well patients with severe
pulmonary hypertension and probably the
commonest cause is COPD but that's only
some patients and the phenotype that
tends to get type 1 Rasputia failure of
those of the emphysema test pink puffer
type phenotype
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