Respiratory Failure

Pathology:                  

Termused to describe failure to maintain oxygenation

Type 1:

hypoxia (PaO₂ <8.0kPa) normal CO₂.This a due to a ventilation/perfusion  

              (V/Q)mismatch (e.g. pulmonary embolus, pneumonia, fibrosis)

Type 2:

hypoxia (PaO₂ <8.0kPa) plushypercapnia (PaCO₂ >6.0KPa). Due to alveolar

hypoventilation(e.g. COPD, neuromuscular disease, sedation)

Aetiology:                    

Pulmonary Disease: Asthma, COPD,pneumonia, pulmonary fibrosis, ARDS

obstructive sleep apnoea, tumour

Thoracic wall:flail chest, kyphoscoliosis

Reduced respiratory drive: sedatives, CNS disorder, brainstemstroke

Neuromuscular: Cervical cord lesions, diaphragm paralysis,poliomyelitis,  

Guillain-Barre,myasthenia gravis

Symptoms:                  

Type 1: Agitation, dyspnoea,tachycardia and confusion

Type 2: Confusion, headache drowsiness

Signs:                              

Type 1: Tachycardia

Type 2: Bounding pulse, tremor, Papilloedema

Investigations:          

ABG: Hypoxia +/- hypercapnia, respiratory acidosis

Treatment:                  

ABCwith appropriate oxygen delivery (beware hypoxic drive in type 2 failure)

Treatunderlying cause

Complications:          

‍Type 2 failure can cause cor pulmonale andpulmonary hypertension

Prognosis:                  

‍30% 1 year survival rate for those requiringventilation

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