Oxygen concentrators draw in ambient air and purify it via special filters. Nitrogen is bound by so-called molecular sieves, so that concentrated oxygen is supplied to the patient via nasal cannulae.
Stationary oxygen concentrators always deliver a continuous flow, i.e. a constant flow rate in liters per minute (l/min). The same amount of oxygen is administered continuously during both inhalation and exhalation. In contrast, mobile oxygen devices deliver a bolus only during inhalation. For this purpose, the patient must be able to trigger the respective oxygen device so that an inhalation is detected.
The setting of an oxygen concentrator is always based on the instructions of the attending physician. The physician takes into account individual aspects and indications as to how many l/min are required both at rest and under stress. For this purpose, among other things, the 6-minute walking test is performed. Depending on the determined need, there are different stationary oxygen concentrators, which differ, among other things, in the flow rate: