Full-Face Mask Use during SCUBA Diving Counters Related Oxidative Stress and Endothelial Dysfunction

Abstract

Impaired flow mediated dilation (FMD), an index of vascular stress, is known after SCUBA diving. This is related to a dysfunction of nitric oxide (NO) availability and a disturbance of the redox status, possibly induced by hyperoxic/hyperbaric gas breathing. SCUBA diving is usually performed with a mask only covering “half face” (HF) and therefore forcing oral breathing. Nasal NO production is involved in vascular homeostasis and, as consequence, can significantly reduce NO possibly promoting vascular dysfunction. More recently, the utilization of “full-face” (FF) mask, allowing nasal breathing, became more frequent, but no reports are available describing their effects on vascular functions in comparison with HF masks. In this study we assessed and compared the effects of a standard shallow dive (20 min at 10 m) wearing either FF or a HF mask on different markers of vascular function (FMD), oxidative stress (ROS, 8-iso-PGF2α) and NO availability and metabolism (NO2, NOx and 3-NT and iNOS expression). Data from a dive breathing a hypoxic (16% O2 at depth) gas mixture with HF mask are shown allowing hyperoxic/hypoxic exposure. Our data suggest that nasal breathing might significantly reduce the occurrence of vascular dysfunction possibly due to better maintenance of NO production and bioavailability, resulting in a better ability to counter reactive oxygen and nitrogen species. Besides the obvious outcomes in terms of SCUBA diving safety, our data permit a better understanding of the effects of oxygen concentrations, either in normal conditions or as a strategy to induce selected responses in health and disease.

Effect of SCUBA Diving on Ophthalmic Parameters

“…This dilatation is significantly reduced after the dive (103 ± 6.5%, p = 0.026). This reduction between the two conditions shows a difference consistent with previously published data and is significant ( p = 0.027) [ 19 ].…”

“…Decreased nitroglycerin-mediated dilation after diving highlights dysfunction in vascular smooth-muscle cells as possible etiology of those results [ 29 ]. Very recent data show that the FMD reduction encountered after a single dive without presence of VGE, is comparable to the reduction encountered with the presence of VGE [ 19 ].…”

Physiology of deep closed circuit rebreather mixed gas diving: vascular gas emboli and biological changes during a week-long liveaboard safari

“…This hypothesis is also supported by the 8-iso-PGF2 increase, which depends on the availability of hydroxyl radicals and by neopterin measurements. This is consistent with former studies demonstrating that 8-iso- PGF2 is increased during hyperoxic oral breathing ( Levenez et al, 2022 ), which was the case during this study. Neopterin is synthesized by human IFN-γ-stimulated macrophages and is indicative of a proinflammatory status, paralleling the increase of ROS which depends on PpO 2 .…”

Vascular Function Recovery Following Saturation Diving

“…In a recent experiment, a similar reduction in FMD was found in a setting excluding bubble formation, but a significant change in FMD was demonstrated depending on the oxygen partial pressure of the breathed gas [ 30 ].…”

“…Very recent data show that the FMD reduction encountered after a single dive without the presence of VGE, is comparable to the reduction found with the presence of VGE [ 30 ].…”