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RESPIRATORY FAILURE / HYPOXAEMIA |
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type 1 respiratory failure (low or normal pCO2): (impaired gaseous exchange across alveolar membrane) |
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acute: |
pulmonary oedema pneumonia bronchial asthma pulmonary embolism ARDS |
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chronic: |
lung fibrosis (any cause; becomes type II later) |
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type 2 respiratory failure (high pCO2): (alveolar hypoventilation) |
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acute (causing asphyxia): |
severe acute asthma |
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upper airways obstruction: |
foreign body laryngeal oedema obstructive sleep apnoea |
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major chest injury: |
flail chest tension pneumothorax massive haemothorax |
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neurological lesions: |
brainstem ischaemia spinal cord trauma transverse myelitis central sleep apnoea respiratory centre depression (opiates)Guillain-Barre syndrome |
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muscle/neuromuscular junction problems: |
myasthenia gravis muscular dystrophy |
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chronic: |
COPD terminally in any progressive respiratory disease severe chest deformity (kyphoscoliosis)gross obesity sleep apnoea syndromes |
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NB: if severe, causes of acute type 1 respiratory failure can also cause type 2 failure
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non-respiratory causes of hypoxaemia: |
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decreased oxygen-carrying capacity of blood [normal pO2]: |
anaemia methaemoglobinaemia CO poisoning |
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R to L shunting of blood |
Eisenmenger's syndrome |
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low inhaled pO2 |
living at high altitudes |
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