ABG

Question 1

What is hypoxia?

Answer 1

Occurs when oxygen is insufficient at the tissue level to maintain adequate homeostasis

Question 2

What is hypoxaemia?

Answer 2

Low oxygen in arterial blood/abnormally low concentration of O2 in the blood where PaO2 is less than 80mm Hg or 10.6 kPa

Question 3

What is cyanosis?

Answer 3

Abnormal blue (blue-ish-purple) discolouration of the skin, nail beds and mucous membranes caused by a shortage of oxygenation of the blood

Question 3

What is hypercapnia?

Answer 3

Condition characterised by increased CO2 concentration in the blood/increase in partial pressure of carbon dioxide (PaCO2) above 45 mm Hg or 6.0

Question 4

What are the respiratory mechanisms of H+ removal from the body?

Answer 4

Increased CO₂ = increased H⁺ = decreased pH = increased depth and rate of breathing to blow off more CO₂

Question 5

What are the metabolic mechanisms of H+ removal from the body?

Answer 5

• Kidneys are responsible for excreting metabolic acids
• They secrete H⁺ ions into the urine and reabsorb HCO₃- (a base) from the urine = reduce H⁺ ions in the blood
• Kidneys can adjust H⁺ and HCO₃- excretion in response to changes in metabolic acid production

Question 6

What is compensation when maintaining acid-base balance?

Answer 6

• The metabolic (renal) and respiratory systems work jointly to maintain blood pH (within 7.35-7.45)
• If one system is overwhelmed, causing a change in pH, the other system usually adjusts automatically