Respiratory Failure

Question 1

What is Respiratory Failure?

Answer 1

Respiratory failure is a syndrome in which the respiratory system fails in one or both
of its gas exchange functions: oxygenation and carbon dioxide elimination.

Question 2

What are the normal values of O2 and CO2 in blood?

Answer 2

The normal reference values are: oxygen PaO2 more than 80 mmHg (11 kPa), and
carbon dioxide PaCO, lesser than 45 mmHg (6.0 kPa).

Question 3

What are the classifications of respiratory failure?

Answer 3

• Hypoxemic (type I)

- Hypercapnic (type Il)

Question 4

What are the characteristics of Hypoxemic type 1?

Answer 4

characterized by a PaO, of less than 60 mm Hg with
a normal or low PaCO. It is typically caused by a ventilation/perfusion (V/Q)
mismatch and shunt (the volume of air flowing in and out of the lungs is not
matched with the flow of blood to the lungs). This is the most common form of
respiratory failure, and it can be associated with virtually all acute diseases of the
lung, which generally involve fluid filling or collapse of alveolar units.

Question 5

What are the causes of type 1 RF?

Answer 5

• cardiogenic or noncardiogenic pulmonary edema,
• pneumonia,
• pulmonary embolism,
• fibrosing alveolitis,
• COPD.
• bronchial asthma,
• pneumothorax.
• bronchiectasis,
• acute respiratory distress syndrome (ARDS),
  fat embolism syndrome,
• kyphoscoliosis,
• obesity.

Question 6

What are the characteristics of Hypercapnic type 2?

Answer 6

characterized by a PaCO, of more than 50 mm Hg.
Hypoxemia is common in patients with hypercapnic respiratory failure who are
breathing room air. The pH depends on the level of bicarbonate, which, in turn, is
dependent on the duration of hypercapnia. Type 2 respiratory failure is caused by
inadequate alveolar ventilation; both oxygen and carbon dioxide are affected.

Question 7

What are the common causes of type 2?

Answer 7

-severe airway disorders (bronchial asthma, COPD, pulmonary edema, ARDS),
-central nervous system disorders (craniocerebral injury, craniocerebral trauma,
stroke and drug overdose and poisonings which cause depression of the neural
drive to breathe),
-neuromuscular diseases (myasthenia gravis, polyneuropathy, poliomyelitis, head
and cervical cord injury),
-chest wall abnormalities (kyphoscoliosis, flail chest, ankylosing spondylitis,
obesity).