Resp Failure

Question 1

What is it?

Answer 1

PaO2 < 8 kPa
Hypoxia - inadequate tissue oxygenation
Hypoxaemia - low arterial o2 levels
Can have hypoxia without hypoxaemia

Question 2

Types of hypoxia?

Answer 2

• cytotoxic
• anaemia
• hypoxic hypoxia (ventilation problem)
• stagnant (shock)

Question 3

Type 1 resp failure

Answer 3

• PaO2 <8kPa & PaCO2 <6kPa (normocapnia) due to impaired oxygenation
• hyperventilation may occur in response = low CO2
• may respond to CPAP

Question 4

Causes of resp failure

Answer 4

• low alveolar ventilation due to alveolar collapse & congestion ; pulmonary oedema, pneumonia, atelectasis, ARDS, pulmonary haemorrhage or airway obstruction (asthma, COPD)
• low alveolar perfusion
• low O2 intake: hypoventilation or low FiO2
• right to left cardiac shunt

Question 5

Type 2 resp failure

Answer 5

• PaO2 <8kPa & PaCO2 >6kPa (hypercapnia) due to impaired ventilation.

Question 6

Causes of type 2 resp failure

Answer 6

COPD
Opiate OD
Resp muscle failure
Severe asthma

May respond to BIPAP
Chronic retainer - long term respiratory acidosis (e.g. COPD) which has been metabolically compensated leading to normal pH.
Acute decomprensation is when pH becomes acidotic