Respiratory Failure

Question 1

Define type 1 respiratory failure

Answer 1

PaO2 < 8 kPa; PaCO2 Normal

Question 2

Aetiology of type 1 respiratory failure

Answer 2

Ventilation-perfusion (V/Q) mismatch
The volume of air passing in and out of the lungs is comparatively smaller than the volume of blood perfusing the lungs.

Question 3

Causes of type 1 respiratory failure

Answer 3

Asthma
Congestive Cardiac Failure
Pulmonary embolism
Pneumonia
Pneumothorax
Low V/Q: areas that have poor ventilation with oxygen but are well perfused by blood. E.g. bronchoconstriction (Asthma), airway collapse in emphysema, mucus plug, congestive cardiac failure
High V/Q: areas of the lung with adequate ventilation but are lacking blood perfusion E.g. Pulmonary embolism.

Question 4

Define type 2 respiratory failure

Answer 4

PaO2 < 8 kPa; PaCO2 > 6 kPa

Question 5

Aetiology of type 2 respiratory failure

Answer 5

Alveolar hypoventilation. This means that the lungs fail to effectively oxygenate and blow off carbon dioxide.

Question 6

Causes of type 2 respiratory failure

Answer 6

Obstructive lung diseases – Chronic obstructive pulmonary disease
Restrictive lung diseases - idiopathic pulmonary fibrosis
Depression of the respiratory center – opiates
Neuromuscular disease – Guillan-Barre syndrome, motor neuron disease
Thoracic wall disease – rib fracture