Oxygen Therapy

Question 1

Mild-moderate hypoxaemia = SPO2?

Answer 1

85-91%

Question 2

Severe hypoxaemia = SPO2?

Answer 2

<85%

Question 3

List the critical illnesses.

(CRITIKALS)

Answer 3

Cardiac arrest
Resus
Injury (Head injury)
Trauma (major trauma)
Infection (severe sepsis)
Ketamine sedation
Anaphylaxis
‘Lepticus (status epilepticus)
Shock

Question 4

How is severe hypoxaemia/critical illness managed?

Answer 4

10-15L/via NRB, consider BVM if inadequate Vt. Titrate to 92-96% once haemodynamically stable. Consider BiPAP.

Question 5

What are the 6 conditions of chronic hypoxaemia? (CCBONS)

Answer 5

COPD
Cystic fibrosis
Bronchiectasis
Obesity
Neuromuscular disorders
Severe kyphoscoliosis

Question 6

Target O2 for chronically hypoxemic pts

Answer 6

88-92% if no critical illness present.

Question 7

5 conditions that receive high flow oxygen regardless of SPO2?

Answer 7

Any likely toxic inhalation exposure
Decompression illness
Cord prolapse
PPPH
Cluster headache

Question 8

Rationale for high flow O2 in toxic inhalation/CO poisoning?

Answer 8

Biological half-life of CO in a healthy adult is 4-5hrs, excreted unchanged via the lungs. CO half-life is decreased with 100% oxygen admin to <90mins due to competitive binding.

Question 9

What are bleomycin and paraquat - why do they receive permissive hypoxaemia?

Answer 9

Paraquat - toxic herbicide
Bleomycin - antineoplastic (chemo agent)

Both agents generate ROS, causing cellular damage in alveoli, liver and kidneys. Supplemental O2 enhances toxic effect by promoting ROS.