ABG

Question 1

Know the components of ABG

Answer 1

pH: acid levels

PaO2/PO2: measures the amount of oxygen dissolved in the blood

SaO2/SO2 (oxygen saturation)
- number of hemoglobin binding sites that has oxygen attached to them

PaCO2/PCO2 (carbon dioxide)
- natural byproduct of cellular metabolism.
- measures the arterial blood levels.
- levels are primarily regulated by the lungs, making PaCO2 the respiratory component of ABG
- CO2 is considered an “acid” in ABG

HCO3 (bicarbonate)
- measures the bicarbonate content of the blood
- concentration is regulated by kidneys and renal production of bicarbonate
- the HCO3 level is the metabolic component of ABG
- a “base” so can accept H+ ions

Question 2

Acid-base disturbances and compensation

Answer 2

If the respiratory system is responsible, the CO2 level will change
- Respiratory Acidosis (build-up of CO2)
- Respiratory Alkalosis (loss of too much CO2)

If the metabolic system is responsible, the bicarbonate level will change
- Metabolic Acidosis (build-up of non-volatile acids)
- Metabolic Alkalosis (reduced amounts of non-volatile acids)

The body will try to compensate for acid-base imbalance through:
- buffer systems
- renal compensation (slow acting up to 1 day- will change bicarb level)
- respiratory compensation (quick acting in minutes- will change CO2 level)