Blood tests

Arterial Blood gas (ABG):
- An ABG is a sample of blood taken from an artery with a needle.
	
- Usually the radial artery at the wrist.
 
 - It measures the levels of oxygen and carbon dioxide in the blood.
 - Some lung diseases can cause low oxygen levels (hypoxia) and some can cause the carbon dioxide levels to be high (hypercapnia).
 - Hypoxia and hypercapnia can be dangerous and need treatment.
 
Full Blood Count (FBC)
A Full Blood Count looks at red and white blood cells.
- The number of red blood cells may be higher if oxygen levels are chronically low to maximise the oxygen carrying capacity of the blood.
 - If red cells are low (in anaemia) this might make the person feel breathless.
 - If there is an infection white blood cell numbers may be higher as they are used to fight off the infection.
 - If the person has recurrent infections then there may be a problem with the white cells and numbers may be low.
 - Some treatments suppress the immune system. A FBC can be used to monitor the side effects.