Clinical Research Directory

Assessment of the Impact of Increased Production of Reactive Oxygen Species Produced During Repeated Sessions of Hyperbaric Oxygen Therapy in Patients Undergoing Radiotherapy for Neoplasia, on the Occurrence of DNA Damage

Hyperbaric Oxygen Therapy (HBOT) is a treatment involving the administration of oxygen at pressures higher than atmospheric pressure, with numerous potential indications such as radiation-induced tissue damage, chronic wounds, and more. HBOT significantly increases the amount of dissolved oxygen in tissues, thereby promoting wound healing. However, this "hyperoxygenation" may also exert toxic effects, particularly through the production of reactive oxygen species (ROS), which can induce DNA damage and potentially promote mutagenesis, thereby increasing long-term neoplastic risk. A single HBOT session is associated with a significant increase in ROS production, which may persist for up to 48 hours post-exposure, and is also linked to DNA damage. DNA repair is typically a rapid process, with the activation of protective mechanisms. The effects of repeated HBOT sessions remain a matter of debate. Reported outcomes range from attenuation of genotoxicity, to exacerbation of DNA damage, or no effect at all (8). In patients with cancer or comorbidities associated with impaired DNA repair capacity, repeated HBOT could be more detrimental, potentially increasing genotoxic effects and cancer risk. This increased oxygen susceptibility in cancer patients has already been observed in normobaric conditions during abdominal surgery, where hyperoxygenation strategies were associated with increased mortality in this subgroup. A potential pro-carcinogenic effect of HBOT in cancer patients has also been suggested in some case series, though not confirmed by larger studies. Current literature on HBOT safety remains generally reassuring; however, the possibility of DNA damage and its potential long-term genotoxic consequences cannot be entirely excluded. This question is of particular importance given that many primary indications for HBOT involve patients with a history of malignancy or active cancer

Effect of Hydrogen Gas on Hyperbaric Oxygen Toxicity

The goal of this trial is to investigate whether adding a small fraction of hydrogen gas to an oxygen-enriched breathing mixture can reduce pulmonary oxygen toxicity (POT) in healthy and active divers from the Swedish Armed Forces. The main questions it aims to answer are: * Does hydrogen gas reduce oxidative stress and changes in pulmonary function associated with prolonged hyperbaric oxygen exposure? * What are the underlying pathophysiological mechanisms of pulmonary oxygen toxicity? Researchers will compare oxygen-enriched breathing gas with 1-2% hydrogen to oxygen-enriched gas with 1-2% nitrogen (control) to see if hydrogen provides protective effects against POT during hyperbaric exposure. Participants will: * Complete two hyperbaric exposure sessions (hydrogen vs. nitrogen), each lasting 240 minutes at 1.75 ATA * Undergo pulmonary function tests and sampling of blod and urin before and after each session * Serve as their own controls in a double-blind, randomized, crossover study design