Backlinkable RT asset
ABG interpretation cheat sheet
This ABG cheat sheet gives RT learners a compact interpretation sequence: classify acid-base status, identify the primary driver, assess compensation, evaluate oxygenation, then choose the safest next action.
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ABG sequence
- Check pH first.
- Compare PaCO2 and HCO3.
- Assess compensation.
- Evaluate PaO2, SpO2, and FiO2 requirement.
- Connect the result to clinical status.
Clinical cautions
- Do not treat the number without assessing the patient.
- Rising PaCO2 plus altered mental status is dangerous.
- Compensation does not automatically mean no intervention is needed.
| Pattern | Likely driver | Clinical question |
|---|---|---|
| Low pH + high PaCO2 | Respiratory acidosis | Does the patient need ventilatory support? |
| High pH + low PaCO2 | Respiratory alkalosis | Is pain, anxiety, hypoxemia, or sepsis driving hyperventilation? |
| Low pH + low HCO3 | Metabolic acidosis | Is shock, renal failure, DKA, or lactic acidosis present? |
Frequently asked questions
- What is the first step in ABG interpretation?
- Start with pH to determine acidemia or alkalemia, then compare PaCO2 and HCO3 to identify the primary process.
- Why include oxygenation after acid-base interpretation?
- A correct acid-base label is incomplete if the patient is hypoxemic, tiring, or needs escalation in oxygen or ventilatory support.