Preflight hypoxia test with portable oxygen concentrators: when new technologies require more technology

Patients with respiratory insufficiency are at risk of hypoxic accidents during commercial flights. Pre-flight hypoxia tests are recommended to identify the risk and titrate oxygenotherapy. Portable oxygen concentrators (POC) are practical for in-flight oxygenotherapy, but their performances at high altitude are imperfectly known. The objective of the present study was to validate the use of a normobaric hypoxic tent as a new modality of evaluation of oxygen therapy devices under flight conditions, before using this system to test patients with their POC. The normobaric hypoxic test was performed with a hypoxic generator connected to an airtight tent. As control, a hypobaric hypoxic test was performed with an altitude chamber specifically designed in order to test a POC, in collaboration with Airbus Defence and Space . Oxygen production of 4 FAA approved POC were measured in these conditions, and compared wih normoxic conditions. In an hypoxic tent simulating an altitude of 2,438 meters, none of the apparatuses tested was able to achieve an FO 2 greater than 80%. The FO 2 was globally 17 [17-18]% lower than that measured in room air (75 [75-76]% versus 93 [92-94]%, p In the altitude chamber, all of the POCs obtained FO 2 values greater than 90%, only 1% [1-2]% lower than that measured in room air (92% [89-92] versus 93% [92-94], p This study indicates that currently flight conditions with a POC cannot be reproduced on the ground without using simple tests as hypobaric hypoxic conditions, which require a disproportionate use of technology.