*Pharmacology (how to prescribe O2)

Question 1

What is FiO2?

Answer 1

The fraction of inspired O2

Question 2

What is SaO2?

Answer 2

Percentage of oxygen saturation of arterial blood

Question 3

What is a major problem (especially with trauma patients) of giving high flow oxygen when they have an SaO2 of 100%?

Answer 3

As you fully saturate all haemoglobin with oxygen, you cannot see a change in SaO2 despite there being a change in pO2

Question 4

What is respiratory failure?

Answer 4

It is defined as a pO2 of less than 8.0kPa. It caused by inadequate gas exchange resulting in hypoxia.

Question 5

What is hypoxia?

Answer 5

Deficiency of oxygen in the tissues

Question 6

What is type 1 respiratory failure?
What causes this?
Examples?

Answer 6

A low pO2 (less than 8.0kPa) with normal or low PaCO2
Caused primarily by ventilation/ perfusion mismatch
e.g. pneumonia, oedema, asthma, emphysema

Question 7

What is type 2 respiratory failure?
What causes this?
Examples?

Answer 7

Hypoxia (PaO2 less than 8.0 kPa) and hypercapnia (PaCO2 greater than 6.0kPa)
Caused by alveolar hypoventilation, with or without V/Q mismatch
e.g. asthma, COPD, reduced respiratory drive, neuromuscular disease, kyphoscoliosis, etc.

Question 8

What is hypoxaemia?

Answer 8

An abnormally low level of oxygen in the blood

Question 9

What is hypercapnia?

Answer 9

Hypercapnia refers to high pCO2(alveolar)

Question 10

What is hypercarbia?

Answer 10

Hypercarbia refers to high pCO2(arterial)

Question 11

Why should you be cautious when giving oxygen to patients with chronic type respiratory failure?

Answer 11

These patients can be in hypoxic drive and therefore are sensitive to high concentrations of inspired oxygen causing them to develop hypercarbia and become acidotic very quickly