Lecture 4: Respiratory Failure Flashcards
1
Q
what is hypoxia
A
reduced level of tissue oxygenation
2
Q
what is hypoxaemia
A
decrease in partial pressure of oxygen in arterial blood
3
Q
how do we measure hypoxaemia
A
- arterial blood gas analyser to see PaO2 (not O2 bound to Hb)
- arterial oxygen saturatation, so percentage of Hb saturated with O2
- using pulse oximetry and arterial blood gas analyser
4
Q
what is type 1 respiratory failure
A
- reduction in PaO2
- no change in PaCO2
- shows V/Q mismatch
- normal alveolar ventilation
5
Q
what is type 2 respiratory failure
A
- reduction in PaO2
- increase in PaCO2
- underventilation of alveoli
6
Q
what are causes of hypoxaemia
A
1) V/Q mismatch
2) right to left shunt
3) diffusion impairment
4) hypoventilation
5) low inspired pO2
7
Q
which causes of hypoxaemia widen the A-a gradient and which don’t affect it
A
widen - V/Q mismatch - diffusion limitation - shunting don't affect - hypoventilation - reduction in inspired O2
8
Q
characteristics of pulmonary shunt
A
- A-a gradient elevated
- normal pCO2
- poor response to oxygen therapy
9
Q
characteristics of diffusion limitation
A
- A-a gradient elevated
- PaCO2 is normal
- hypoxaemia shows good response to oxygen therapy
10
Q
characteristics of hypoventilation
A
- high PaCO2
- low PAO2 and PaO2
- normal A-a gradient
- easily corrected by oxygen therapy
