Understanding Low Oxygen Saturation (SaO2) in Asthma: Causes & Explanations

Low Sa02 sats, or low oxygen saturations, in asthma patients are due to a process by which inflamed and constricted airways prevent adequate perfusion (oxygenation) of the bloodstream.

Understanding Asthma

• Asthma is a condition in which the air pipes, or bronchi, suddenly begin to narrow as a result of inflammation. Smooth muscle tissue inside the bronchi contract during what is termed brochoconstriction, leading to breathing irregularities.

The Asthma Attack

• During an asthma attack, the narrowing of the airways leads to increased breathing exertion in an attempt to force air in and out of the lungs.

Development of Hypoventilation

• The struggle to breathe, which is characterized in asthmatics by chest tightness, coughing and wheezing, can lead to a condition of ̶0;underbreathing̶1; or respiratory depression known as hypoventilation.

Inadequate Gas Exchange

• Poor ventilation causes increased carbon dioxide retention and decreased oxygen saturation, as the lungs are incapable of performing properly.

Measurement and Terminology

• Sa02 stands for arterial oxygen saturation. This measurement is captured by a pulse oximeter (probe on the finger), which will indicate lower oxygen levels in these asthma patients.