Respiratory Failure - ARDS
26 year old man with no past medical
history developed progressive shortness
of breath and cough with fevers. His vital
signs in the medi-centre are 102/60, heart
rate 112, respiratory rate of 30 and oxygen
saturations of 84% on room air.
 EMS is called and he is taken to the ER.
Enroute, he is given flush oxygen and his
saturation improve to 87%.
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Admission CXR
This patient is hypoxic despite flush
oxygen. What is the primary
pathophysiology behind the hypoxia?
 How does shunt cause hypoxia and why is
it resistant to oxygen therapy?
 What is your initial management?
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His condition continues to decline. His
shortness of breath worsens and he starts
to become confused. His oxygen
saturations are now 83%.
 What is the role for non-invasive
mechanical ventilation at this time?

CXR 12 hours post admission
What has happened?
 The patient has been intubated and is now
on an FiO2 of 80%. His last ABG
demonstrates a pH of 7.30, PCO2 40,
PO2 60, HCO3 18.
 How is the diagnosis of acute respiratory
distress syndrome (ARDS) made and how
is it different from acute lung injury?
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List conditions that predispose to
developing ARDS.

Consider:
 Sepsis
 Aspiration
of gastric contents
 Severe trauma and burns
 Massive blood transfusion
 TRALI
 Drugs and alcohol
 Bone marrow transplant

Describe the pathophysiological stages of
ARDS.
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Inflammatory stage
Edema formation
Fibrosis
What are some of the consequences of ARDS

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Impaired gas exchange – V/Q mismatch and shunt
Decreased lung compliance
Pulmonary hypertension
Over the course of the next 12 hours, his
oxygen requirements continue to climb.
The RT reports that he is very difficult to
ventilate and needs high airway pressures
to maintain a normal PCO2.
 What are the consequences of the current
ventilation strategy?
 What other way can he be ventilated?

What is barotrauma, volutrauma, and
atelecatrauma?
 How does lung protective ventilation
mitigate the above traumas?
 Two days later, the patient has a sudden
deterioration in oxygenation and blood
pressure. CXR reveals:
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What are some other complications of prolonged
mechanical ventilation and ARDS?
After the chest tube is inserted, the patient’s
ventilation continues to be a problem with a pH
of 7.15 and oxygen saturations of 81% on
maximal lung protective ventilation.
What other rescue ventilation strategies could be
tried?
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After converting to HFOV, the patient stabilizes.
Four days later, his oxygen requirements
increase to 100% again and he develops a fever
and WBC of 15.3 with 10% bands.
What has likely happened?
How can we find out?
How is a ventilator associated pneumonia
different from other pneumonias?
How is it treated?
Questions??