ABG Components
What is the normal range for pH in an ABG?
7.35-7.45
What is the primary cause of respiratory acidosis?
Hypoventilation
If a person has respiratory acidosis, how does the body compensate?
The kidneys retain bicarbonate.
A patient with COPD presents with confusion and a PaCO2 of 55 mmHg. What do the ABG results likely show?
Respiratory acidosis.
What would a normal ABG look like?
pH 7.4, PaCO2 40 mmHg, HCO3 24 mEq/L, PaO2 90 mmHg.
What does PaCO2 measure in an ABG?
The partial pressure of carbon dioxide in arterial blood.
What condition is associated with metabolic alkalosis?
Vomiting, diuretic use, or excessive loss of acids.
How does the body compensate for metabolic acidosis?
The lungs increase ventilation to lower PaCO2.
A patient with diabetes presents with fruity breath and a pH of 7.2. What type of acid-base disorder do you expect?
Metabolic acidosis (due to diabetic ketoacidosis).
Is this ABG normal or abnormal: pH 7.48, PaCO2 30 mmHg, HCO3 22 mEq/L?
Abnormal. It indicates respiratory alkalosis.
What is the normal range for bicarbonate (HCO3) in ABGs?
22-26 mEq/L
What does a low pH and low HCO3 indicate?
Metabolic acidosis
If a patient has respiratory alkalosis, how does the body compensate?
The kidneys excrete bicarbonate.
A patient has severe vomiting for 48 hours. What would you expect in their ABG results?
Metabolic alkalosis.
Is this ABG normal or abnormal: pH 7.20, PaCO2 50 mmHg, HCO3 28 mEq/L?
Abnormal. It suggests respiratory acidosis with metabolic compensation.
What is the normal PaO2 range in an ABG?
80-100 mmHg
What is the primary cause of respiratory alkalosis?
Hyperventilation
What compensatory mechanism occurs in metabolic alkalosis?
The lungs decrease ventilation, leading to increased PaCO2.
A patient is hyperventilating due to anxiety. What would you expect to see in their ABG?
Respiratory alkalosis
What does this ABG indicate: pH 7.38, PaCO2 70 mmHg, HCO3 23 mEq/L?
Respiratory acidosis.
Which value in the ABG indicates respiratory status (ventilation)?
PaCO2
What ABG findings would indicate a mixed acid-base disorder?
Abnormal pH with both respiratory and metabolic changes present.
How can you tell if an acid-base imbalance is uncompensated on an ABG?
The pH is abnormal, and only one of the other values (CO₂ or HCO₃⁻) is abnormal.
A patient with severe shock and multi-organ failure presents with a PaCO2 of 60 mmHg and HCO3 of 18 mEq/L. What is the most likely diagnosis?
Mixed respiratory acidosis and metabolic acidosis.
Is this ABG normal or abnormal: pH 7.32, PaCO2 42 mmHg, HCO3 15 mEq/L?
Abnormal. It indicates metabolic acidosis.