Background. The medical relevance of therapeutic gases can range from use in burns and stroke victims to hypoxia therapy in children. However, medical gases such as oxygen, hydrogen, helium and xenon have recently come under increased exploration for their potential therapeutic use on various brain disease states, including traumatic brain injuries, hypoxia-ischemia and, cerebral hemorrhages.

Objective. This synthetic review aims to rigorously select related articles and identify within their content the main possible uses of therapeutic gases and physiological mechanisms. The objective of this article is to present the various therapeutic mechanisms that have been proposed in the current literature and the medical relevance of various therapeutic gases used in balneotherapy or medical rehabilitation.

Methods. To elaborate our synthesis review, we have searched for relevant open access articles in 6 international databases: Cochrane1 , Elsevier1 , NCBI/PubMed1 , NCBI/PMC1 , PEDro1 , and ISI Web of Knowledge/Science1 , published from January 2011 until December 2020. The contextually quested keywords combinations/ syntaxes used are specified on this page. The eligible articles were analyzed in detail regarding pathologies addressed by therapeutic gases. All articles with any design (reviews, randomized controlled trials, nonrandomized controlled trials, case-control studies, cross-sectional studies), if eligible according to the above-mentioned selection methodology, containing in the title or abstract the above-mentioned combinations, were included in the analysis. Articles were excluded in the second phase if they did not reach the relevance criterion.

Results. Our search identified, first, 225 articles. After eliminating the duplicates, remained 180 articles. In the second phase, we applied a relevance criterion. Although our team - including the authors of this paper – have quite long and consistent expertise in achieving systematic literature reviews, the marked heterogeneity of both the item composing the subject we have approached and inherently the wase of presentations in the respective quite vast and diverse domain of medical gases, prevented us to fulfil, at least regarding this initial work, a systematic literature review. Instead, we succeeded to make a hopefully interesting and valuable narrative synthetic-related literature review. At the end of the second phase, 63 articles passed the relevance criterion and were included in this synthetic review.

Conclusions. Therapeutic gases are not fully understood and used adequately for sanogenic or medical purposes. More research is needed to fully understand the mechanisms and importance of therapeutic gases. The link between balneotherapy and medical rehabilitation regarding the usage of therapeutical gases emphasises the unity for this medical speciality.