SpO2 (Peripheral Oxygen Saturation) is one of the most commonly used vital signs in healthcare. It measures the percentage of oxygen-saturated hemoglobin in the blood.
Simply put, it tells you how much of the oxygen your blood is carrying is being delivered to the peripheral parts of your body (like fingers or earlobes).
- What is it ?
- Sp : Peripheral capillary oxygen saturation (measured by a pulse oximeter)
- O2 : Oxygen
- Normal values are typically 95% to 100%.
- A reading below 90% is generally considered hypoxemia and requires medical attention.
- How is it measured ?
- Using a pulse oximeter—a small clip placed on a finger, toe, or earlobe.
- Principle: It uses the property that oxygenated and deoxygenated hemoglobin absorb red and infrared light differently. A sensor calculates the saturation percentage.
- Why is it important ?
- Provides a quick and non-invasive assessment of a person’s oxygenation status.
- Monitors patients with respiratory conditions (e.g., asthma, pneumonia, COPD, COVID-19).
- Used during surgical anesthesia, intensive care, rehabilitation, and home health management.
- Normal Range & Interpretation:
- 96%-100% : Normal range.
- 95% : Usually acceptable, but warrants observation.
- 90%-94% : Low, may indicate hypoxia. Inform a healthcare professional (especially for individuals with lung disease).
- Below 90% : Medical alert. Significant hypoxia, requires immediate medical care.
- Note: Some patients with chronic lung diseases (e.g., severe COPD) may have a lower “normal” baseline (e.g., 88%-92%). Doctors provide individualized targets.
- Limitations / Factors Affecting Accuracy:
- Not a substitute for arterial blood gas (ABG) analysis : SpO2 only measures oxygen saturation, not carbon dioxide levels or acid-base balance.
- Readings can be inaccurate : Readings may be unreliable in cases of poor peripheral circulation(cold, low blood pressure, shock),nail polish/artificial nails, skin pigmentation, patient motion, severe anemia, or carbon monoxide poisoning (which can show a deceptively normal/high value).
Simple Summary :
SpO2 is a key indicator of how efficiently blood carries oxygen. It should normally stay above 95%. It is an extremely useful monitoring tool, but readings must be interpreted in the context of the patient’s overall symptoms (e.g., shortness of breath, chest pain, altered mental status) and clinical situation. Seek professional medical help for abnormal readings or if feeling unwell.