Respiratory Failure

Question 1

What is respiratory failure?

Answer 1

A decrease in the partial pressure of oxygen (PaO2) in the blood

Question 2

What is the normal PaO2?

Answer 2

11 – 13 kPa || 82.5 – 97.5 mmHg

Question 3

What decrease in PaO2 is resp failure?

Answer 3

<8kPa

Question 4

What are the two types of respiratory failure?

Answer 4

Type I
Type II

Question 5

What does Type I respiratory failure involve?

Answer 5

Hypoxaemia: (PaO2 <8 kPa / 60mmHg)

With normocapnia (PaCO2 <6.0 kPa / 45mmHg).

PaO2 < 8 kPa; PaCO2 Normal

Question 6

What does Type II respiratory failure involve?

Answer 6

Hypoxaemia and hypercapnia

PaO2 < 8 kPa; PaCO2 > 6 kPa

Question 7

What does T1 resp failure occur as a result of?

Answer 7

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 8

Causes of Type I respiratory failure

Answer 8

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 9

What does T2 resp failure occur as a result of?

Answer 9

Alveolar hypoventilation.

Prevents the patient from being able to adequately oxygenate and eliminate CO2 from their blood.

Question 10

What causes type two respiratory failure?

Answer 10

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