Respiratory Failure

Question 1

What is respiratory failure

Answer 1

when gas exchange is inadequate resulting in hypoxia

Question 2

What is type I respiratory failure?

Answer 2

• Hypoxia (PaO2 <8kPa) with a normal PaCO2

Question 3

What causes type I respiratory failure?

Answer 3

• Caused primarily by ventilation/perfusion (V/Q) mismatch, hypoventilation, abnormal diffusion and R-L cardiac shunts

Question 4

What are the major causes of type I respiratory failure?

Answer 4

o	Pneumonia
o	Pulmonary Oedema
o	Asthma
o	PE
o	Emphysema
o	Pulmonary fibrosis
o	ARDS

Question 5

What is type II resp failure?

Answer 5

• Hypoxia (PaO2 <8kPa) with hypercapnia (PaCO2 >6kPa)

Question 6

What causes type II respiratory failure

Answer 6

• Caused by alveolar hypoventilation with or without V/Q mismatch

Question 7

What diseases are responsible for type II resp failure?

Answer 7

o Pulmonary disease: asthma, COPD, pneumonia, end-stage pulmonary fibrosis, obstructive sleep apnoea
o Reduced respiratory drive: sedative drugs, CNS tumour, trauma
o Neuromuscular disease: cervical cord lesions, diaphragmatic paralysis, poliomyelitis, myasthenia gravis, Guillain-Barré syndrome
o Thoracic wall disease: Flail chest, kyphoscoliosis

Question 8

What are the clinical features of hypoxia?

Answer 8

• Dyspnoea
• Restlessness
• Agitation
• Confusion
• Central cyanosis
• If long standing: Polycythaemia, Pulmonary hypertension, Cor pulmonale

Question 9

What are the clinical features of hypercpania?

Answer 9

• Headache
• Peripheral vasodilation
• Tachycardia
• Bounding pulse
• Tremor/flap
• Papilledema
• Confusion
• Drowsiness
• Coma

Question 10

What investiagtions should be carried out in resp failure?

Answer 10

• Blood tests: FBC, U&E, CRP, ABG
• Radiology: CXR
• Microbiology: sputum and blood cultures (if febrile)
• Spirometry (COPD, neuromuscular disease, Guillain-Barré syndrome)