The oxygen concentration in our daily air is about 21%, and COPD needs to reach 29%-35% to have a therapeutic effect. (Note: The concentration mentioned here is the oxygen absorption concentration.)

The concentration of the oxygen concentrator refers to the purity of the output oxygen. In order to ensure long-term use and therapeutic effect, patients with COPD should choose an oxygen concentrator with an oxygen concentration ≥90%.

How to calculate the oxygen concentration?

Oxygen absorption concentration (%) = 21% + 4% × oxygen flow (L/min)

What is oxygen flow? When you buy an oxygen concentrator, will find that there are 1L, 2L, 3L, and 5L different types of oxygen concentrator on the market. These different numbers represent the oxygen flow per minute of the oxygen concentrator.

It can be seen from the formula that the oxygen concentration of the patient is determined by the oxygen flow. Therefore, many patients believe that the higher the oxygen flow, the higher the oxygen concentration. This is wrong, because high flow ≠ high concentration.

Taking a 3L oxygen concentrator as an example, when the oxygen flow is adjusted in the range of 0.5~3L/min, the oxygen concentration can be guaranteed to reach the standard, and when the oxygen flow is adjusted to more than 3L/min, the oxygen concentration will decrease instead.

Therefore, when a patient buys an oxygen concentrator, they should not only pay attention to the large flow rate. The oxygen concentration must ≥ 90%. This oxygen concentration cannot be attenuated with the change of flow rate or working time.