causes of hypoxemia and hypercapnia

Question 1

what are the fundamental causes of hypoxemia ?

Answer 1

• insufficient ventilation
• insufficient rate of gas exchange
• insufficient oxygen carrying capacity
• insufficient oxygen in the atmosphere

Question 2

list some clinical signs and pathological changes associated with the causes of hypoxemia

Answer 2

Question 3

describe type 1 and 2 respiratory failure

Answer 3

Question 4

how do you interpret ABG readings using AGE and A-a gradient ?

Answer 4

Is hypoventilation contributing to hypoxaemia?
* is PaCO2 > 6kPa?
Is the oxygen that reaches the alveoli diffusing into the blood?
* Use AGE and ABG readings to calculate A-a gradient (A-a should be less than ≈2kPa)

Question 5

what are the effects of acute hypoxemia and hypercapnia ?

Answer 5

Effects of insufficient O2 supply:
Clinical signs = dyspnoea (shortness of breath), cyanosis, fatigue,
coma, seizure
Pathophysiology = Respiratory dysfunction > hypoxaemia > tissue
hypoxia (e.g. cerebral-, cardiac-, renal hypoxia) > acidosis (due to
reliance on anaerobic respiration in absence of sufficient O2, cellular
dysfunction & injury > organ failure -> death

Effects of insufficient carbon dioxide removal:
Clinical signs = dyspnoea/elevated breathing, agitation, confusion,
seizure, unconsciousness
Pathophysiology = Hypercapnia > acidosis > organ failure
(e.g. via hyperkalaemia + local tissue dysfunction/injury > death

Question 6

What clinical signs would we expect to see when different aspects of respiration fail?

Answer 6