Respiratory Failure Flashcards
What is the pa02 required for hypoxia
<8.0kPa
What can cause hypoxia?
- Hypoventilation
- Failure of gas exchange
- V/Q mismatch
- Right to Left cardiac shunt
- Low inspired oxygen
Consequences of hypoxia?
Dyspnoea Restlessness Agitation Increased RBC Cor pulmonale
How do you define type 1 respiratory failure?
PaO2< 8.0kPa
Sa02 approx 90%
pCO2 normal or low
What is the physiology of type 1 respiratory failure?
- Hypoxia
- Increased ventilation
- More CO2 exhaled
- Hypoxic but not hypercapnic
What can cause reduced ventilation leading to a V/Q mismatch?
- lung collapse
- pneumothorax
- pneumonia
- pulmonary oedema
What can cause reduced perfusion leading to a V/Q mismatch?
PE
What is pulmonary shunt
Normal perfusion, poor ventilation
V/Q=0
What is alveolar dead space
Poor perfusion, good ventilation
V/Q= infinity
Define type 2 respiratory failure
Low oxygen (<8kPa) High Co2 (>6.7kPa) pH <7,35
Describe the pathogenesis of type 2 respiratory failure
- Pao2 falls
- Cannot increase ventilation
- High pCO2
- Dissolves into carbonic acid
- pH <7.35
What can cause type 2 resp failure?
Obstruction (asthma/ COPD)
Hyperexpanded lungs (COPD)
Thoracic cage pathology
Weakness of resp muscles
Describe the process of normal expiration
Relaxation of muscle and diaphragm relax
Leads to elastic recoil forcing lungs to contract
The chest pressure > the outside pressure
Air is pushed out
Describe the process of normal inspiration
Intercostal muscles and diaphragm contract
Pressure inside chest less than outside
Air pulled in
What oxygen treatment should be used for type 1 resp failure
- Correct oxygen with high flow mask (60-100%)
- CPAP if still hypoxic
