Oxygen

Question 1

What is oxygen used for?

Answer 1

• hypoxia
• accelerate reabsoprtion of pleural gas in pneumothorax
• reduce half life of carboxyhaemoglobin in carbon monoxide poisoning

Question 2

What is the mechanism of oxygen therapy?

Answer 2

hypoaxaemia is when the PaO2 in arterial blood is abnormallly low.

O2 supplementation will increase the PaO2 so increased O2 delivery to tissues.

In pneumothoras O2 reduces the proportion of nitrogen in alveolar gas. This acclerates the diffusion of nitrogen out of the body. Pleural air is mostly nitrogen so this increases the rate of its reabsorption.

In CO poisoning, O2 competes with Co to bind to haemoglobin. This shorten’s the half life of COhaemoglobin.

Question 3

What are the side effects of oxygen treatment?

Answer 3

• discomfort of facemask

- dry throat

Question 4

What are the contraiindications of oxygen treatment?

Answer 4

• Chronic type 2 resp failure.

- active smokers (heat source / naked flame)

Question 5

what is a reservoir (non-rebreathing) mask

Answer 5

It a mask that has a bag that is continuously filled up with incoming oxygen. Inspired gas comes from this bag which has a high conc of oxygen (60-80%)

Question 6

what is the oxygen flow rate with a non re-breath mask?

Answer 6

15 L/min

Question 7

What is a venturi mask?

Answer 7

A venturi mask blends oxygen with air in a fixed ratio. different venturi masks have different oxygen flow rates.

Question 8

What is the oxygen conc and flow delivered through a nasal cannulae?

Answer 8

conc = 24-50%

rate 2-6L/min