Arterial Oxygen Content (CaO₂)
Calculates total arterial oxygen content — oxygen bound to haemoglobin plus dissolved in plasma. Used to assess oxygen delivery (DO₂ = CaO₂ × CO × 10).
Score interpretation
CaO₂ < 15 mL/dL: Reduced arterial oxygen content. May indicate anaemia, hypoxaemia, or impaired oxygen binding.
→ Identify cause: anaemia (transfuse if Hb < 7 g/dL or symptomatic), hypoxaemia (increase FiO₂, CPAP, ventilation), methaemoglobinaemia. Consider oxygen delivery calculation (DO₂ = CaO₂ × CO × 10).
CaO₂ 15–22 mL/dL: Normal arterial oxygen content.
→ Adequate oxygenation. Ensure sufficient cardiac output. Monitor VO₂ if critically ill.
CaO₂ > 22 mL/dL: Elevated. Consider polycythaemia.
→ Consider polycythaemia vera, secondary polycythaemia (COPD, high altitude, EPO use). Investigate haematology. Hyperviscosity risk.
Interpretation bands for the CaO₂. Apply clinical judgement and local guidance.
References
- West JB. Respiratory Physiology: The Essentials. 9th ed. Lippincott Williams & Wilkins, 2012.
Related
Curated clinical cross-links plus same-class fallbacks.
- Acute Asthma in Adults · BTS/SIGN British Guideline on Asthma 2019; NICE NG80
- Pulmonary Embolism Assessment · NICE NG158; ESC 2019 PE Guidelines
- Acute Exacerbation of COPD (AECOPD) · NICE NG115; GOLD 2024
- Spontaneous Pneumothorax (Adult) · BTS Pleural Disease 2023
- Atypical Pneumonia (Legionella / Mycoplasma / Chlamydophila) · BTS 2023; IDSA
- COPD Exacerbation Management · NICE NG115 / GOLD 2024
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.