Respiratory Failure – COPD and Asthma

Respiratory Failure – COPD
and Asthma
59 year old man presents to the ER with a
3 day history of progressively worsening
shortness of breath.
He has a past history of chronic lung
disease that started about 5 years ago and
he is an ex-smoker for about 6 months
since his family doctor threatened to put
him on home oxygen.
What additional information do you want on
The patient states that he has had a chronic
productive cough for years and over the last
week he has noticed a changed in the amount
and color of his sputum.
Denies any recent travel, sick contacts (although
grandkids visited about 10 days ago), fevers,
chest pain, orthopnea, past hospitalizations or
Still works as an accountant.
Initial CXR
On examination, his chest sounds are distant
with some wheeze and prolonged exhalation.
Heart sounds are difficult to hear.
He is unable to speak in complete sentences
and is in moderate to severe respiratory distress.
Room air ABG: pH 7.19, PCO2 76, PO2 53,
HCO3 35
WBC 12.7, Bands 9%, Hgb 186, Platelets 250
What is the most likely diagnosis?
What is the differential diagnosis?
Why is the PCO2 elevated?
– What are the determinants of blood CO2
– What is dead space ventilation and what is the
difference between anatomical and physiological
dead space?
– How is dead space ventilation different from shunt?
Why is the PO2 low?
What are the factors that influence
respiratory muscle strength?
– Consider:
Electrolyte derangements
What are the factors that influence respiratory
muscle load?
– Consider:
Dynamic hyperinflation
Increase CO2 production
Abdominal distension
What is the relationship between
respiratory muscle strength and load in
acute on chronic respiratory failure?
The patient’s respiratory distress has not
improved with all of this physiology talk.
What is the approach to the treatment of
acute on chronic respiratory failure in the
emergency department?
After starting frequent bronchodilators,
steroids and empiric antibiotics, the patient
is not feeling better.
What is the role for non-invasive positive
pressure ventilation for this problem?
What are the indications and
contraindications for NIPPV?
How does NIPPV work in acute on chronic
respiratory failure?
After applying NIPPV, the patient begins to
feel better and eventually is transferred to
the ward.
If he had not improved, how would you
know and what would you do?
Bonus question: What causes the PCO2
to rise on high flow oxygen? How
common is it? Which is more harmful;
hypercarbia or hypoxemia?
Next Case…
19 year old woman with a 12 year history of
asthma presents to the ER with 3 day history of
increasing shortness of breath and cough.
She recently rescued a cat from the pound and
started dating a boy who smokes.
She has been to the ER about one per year for
asthma attacks, admitted twice and never in
She uses ventolin about 6 times per day.
On examination, she is in severe
respiratory distress with a rate of 31, pulse
124, and O2 saturations of 100% on face
Her blood pressure is 151/83 with a pulsus
paradoxus of 25.
What is a pulsus paradoxus?
If her pulsus was 15, would you be
What investigations would you order?
What treatments would you order?
What is the role of heliox and non-invasive
positive pressure ventilation in severe
Her ABG on face mask is: pH 7.20, PCO2
35, PO2 123, HCO3 17
Is this a reassuring ABG? Why or why
After 35 minutes of continuous therapy,
her work of breathing is about the same,
she can speak in short words only and is
becoming difficult to arouse.
What do you do next?
What are the indications for intubation in
severe asthma?
She is successfully intubated on the first
attempt. Immediately after her blood pressure
starts to fall and she becomes pulseless but the
monitor still shows electrical activity.
What could be causing this PEA arrest?
– Consider:
Loss of vascular tone
Electrolyte disorders; especially pH
Overventilation on the Ambu Bag
The RT reports that she is very stiff to bag
but after disconnecting her from the bag
and waiting 30 seconds, she regains a
What is dynamic hyperinflation?
What are the consequences of dynamic
Now that she is on the ventilator and more
stable, what treatments would you use for
her asthma?
How would you ventilate her?
Despite permissive hypercarbia, she is still
difficult to ventilate?
What other treatments are available?