携帯用酸素療法機器の製品、性能、技術開発：スコーピングレビュー

Ambulatory oxygen therapy is prescribed for patients with chronic lung diseases who experience exertional hypoxemia. However, the available ambulatory oxygen therapy devices may not adequately meet users' requirements and their performance characteristics are heterogeneous.

To identify devices available for delivery of ambulatory oxygen therapy, the technologies that they utilize to generate oxygen, the performance characteristics of each device, and the development status.

Medical and engineering databases were used to identify peer-reviewed papers (e.g., MEDLINE, IEEE). A grey literature was used to identify additional descriptions of ambulatory oxygen devices in military medicine, space exploration or patents. The last search was conducted in September 2025. Documents that described a device that can deliver oxygen in an ambulatory context (defined as weighing less than 10kg) and written in English were included. Search results were screened for inclusion by two independent reviewers. Data were synthesized by descriptively mapping the performance of each product, the technology used, and development status of emerging technologies.

From 9,702 records identified, 166 met eligibility criteria (106 scientific publications and 60 grey literature). We identified 33 portable oxygen concentrators (POCs, 29 commercially available), 10 oxygen cylinders, and 6 portable liquid oxygen (LOX). The POC products showed a trade-off between portability and oxygen delivery capacity (maximum flow rate ranging 2.0 to 6.0 LPM, device weight ranging 1.0 to 9.1 kg). Pressure swing adsorption with zeolite were the most common oxygen generation technologies in POCs on the market. The mean maximum continuous operating time of POCs was 3.8 hours. Two prototype POCs with a maximum flow rate of 4 - 6 LPM and device weight of 8 - 9 kg have been developed in the space exploration field using modified adsorbents. LOX devices were the lightest and had the longest continuous operating time. Innovations in delivery included the downsizing of a POC by using nanozeolite as adsorbent and SpO₂-targeted automatic titration of oxygen delivery based on the user's SpO₂.

This scoping review is the first study to integrate medical, engineering, and grey literature on ambulatory oxygen devices and their development. Although prior literature had narratively explained the products and technologies, no previous research had systematically investigated them. This review showed that POCs available to consumers may not meet the needs of patients in terms of flow rate, portability, and operating time. LOX offered superior performance but is limited by high costs. Limitations of this review include the difficulty of comparing product performance across oxygen delivery settings, and the records were largely obtained from English-language sources. In conclusion, innovation in ambulatory oxygen technology has been limited over the past decade. There is an urgent need for research and development in new lightweight devices with greater oxygen delivery capacity.

Open Science Framework; https://osf.io/qs7fx.