The oxygen saturation

What is the oxygen saturation?

Oxygen saturation describes what percentage of the red blood pigment (hemoglobin) is loaded with oxygen. It is important for assessing respiratory function. The oxygen saturation can be influenced by various factors.

One important variable is age. In children and young adults the saturation should be 100%, whereas it can drop to 90% with age. PH, temperature and carbon dioxide concentration also play a role. In addition to the individual variables, different clinical pictures (COPD, heart failure, etc.) can negatively influence oxygen saturation.

Where can the oxygen saturation be measured everywhere?

There are two methods to determine oxygen saturation. The simple measurement is done with a pulse oximeter – a small device that measures light absorption and thus indicates oxygen saturation. The pulse oximeter can be attached to a finger or even to the earlobe.

After a short time the value is shown on the display. However, measuring errors can occur with this method, which is why blood gas analysis is suitable for more precise examinations. For the blood gas analysis, blood is taken from an artery of the patient.

Usually the blood is taken from an artery located at the wrist. In this analysis, parameters such as oxygen saturation, carbon dioxide partial pressure and acid-base balance are recorded. This allows a comprehensive diagnosis and allows conclusions to be drawn about the underlying disease.

When should oxygen saturation be monitored?

The oxygen saturation is routinely monitored by an anesthesiologist (anaesthetist) during every anaesthesia. During anaesthesia, the patient is artificially ventilated, which is why saturation is an important parameter in determining whether the patient’s tissue or organs are sufficiently supplied with oxygen. Furthermore, in intensive care and emergency medicine, oxygen saturation is monitored.

In emergency medicine one wants to get an impression of the patient and the functions of his body circulation. Through the oxygen saturation the respiratory function can be assessed. If necessary, oxygen can also be supplied to the patient.

In intensive care medicine, however, patients are usually unstable and breathing is only possible to a limited extent. In this case oxygen must be supplied. The quantity required for this can be calculated based on the oxygen saturation.

Furthermore, patients suffering from chronic lung diseases should be monitored. These include diseases such as COPD, bronchitis, bronchial asthma or cystic fibrosis (congenital metabolic disease). But also other diseases, such as heart failure, can have a negative effect on saturation.

If the oxygen saturation is poor or drops, oxygen can be supplied to the patient. This is particularly important for patients with end-stage COPD. These patients have to control their saturation independently at home and adjust their oxygen requirements.