Respiratory failure Flashcards
When does resp failure occur?
When gas exchange is inadequate, resulting in hypoxia.
Resp failure is defined as … and how is it subdivided into types?
Defined as PaO2 < 8kPa
Subdivided according to PaO2 levels
What is the definition of type 1 resp failure?
Hypoxia (PaO2 < 8) with a normal or low PaCO2
What are the causes of type 1 failure?
ventilation/perfusion mismatch (V/Q)
hypoventilation
abnormal diffusion
right to left cardiac shunts
Give some examples of V?Q mismatch.
Pneumonia Pulmonary oedema PE Asthma Emphysema Pulmonary fibrosis ARDS
What is the definition of Type 2 Resp failure?
Hypoxia (PaO2 < 8) with hypercapnia (PaCO2 . 6.0 kPa)
What causes the criteria of type 2?
Alveolar hypoventilation, with or without V/Q mismatch
What are some fo the causes of type 2 failure?
Pulmonary disease - asthma, COPD, pneumonia, end-stage pulmonary fibrosis, obstructive sleep apnoea.
Reduced resp drive - sedatives, CNS tumour, trauma.
Neuromuscular disease - diaphragmatic paralysis, myasthenia graves, Gillain-Barré syndrome.
How would you manage type 1 respiratory failure?
Treat the underlying cause
Give O2 (24-60%) by face mask
Assisted ventilation if PaO2 < 8 despite 60% O2
What do you need to remember when treating type 2 respiratory failure?
The respiratory centre may be relatively insensitive to CO2 and respiration may be driven by hypoxia.
How would you treat type 2 respiratory failure?
Treat underlying cause.
Controlled O2 therapy: start at 24% O2
Recheck ABG after 20 mins; if PaCO2 steady/lower, increase O2 concentration to 28%. If PaCO2 has risen and patient is still hypoxic, consider assisted ventilation.
If this fails consider intubation and ventilation.
