View clinical trials related to Hypoxia, Altitude.
Filter by:Not uncommonly, sports events take place or finish at high altitude, where physical and cognitive (e.g. decision-making, motor control) performance in hypoxia is determining the outcome of sports performance. With nutritional supplements growing in popularity in the athletic and non-athletic population, research is increasingly focussing on dietary constituents which can improve cognitive and exercise performance. Flavonoids, a subgroup of polyphenols, are a class of natural compounds found in the human diet and include subcategories of flavanols, flavonols, iso-flavones, flavones, and anthocyanidins. Intake of flavanols, found in grapes, tea, red wine, apples and especially cocoa, causes an nitric oxide (NO)-mediated vasodilatation and can improve peripheral and cerebral blood flow (CBF). For cocoa flavanol (CF), there is evidence that both long term and acute intake can improve cognitive function, with the quantity and bioavailability of the consumed CF highly influencing its beneficial effects and with higher doses eliciting greater effects on cognition. Increased CBF following acute and chronic (3 months) CF intake has been demonstrated in healthy young subjects. Moreover, cognitive performance and mood during sustained mental efforts are improved after acute CF intake in healthy subjects and CF intake can increase prefrontal oxygenation during cognitive tasks in well-trained athletes. Moreover, CF intake is not only associated with an improved blood flow, but it might also improve exercise performance following 2 weeks of dark chocolate intake. On top of that, CF is known to have anti-oxidant properties and 2 week CF intake has been associated with reduced oxidative-stress markers following exercise. In hypoxic conditions, arterial pressure of oxygen (PaO2) and arterial saturation of O2 (SaO2) are decreased, compromising tissue oxygen delivery. Since brain function and brain integrity are dependent on continuous oxygen supply, brain desaturation may result in an impaired cognitive function in hypoxia. The severity of the impairment is related to the extent of high altitude, with at 3000m (=14.3 % oxygen (O2); = 71% of oxygen available at sea level) psychomotor impairments being visible. Cerebral oxygenation, which can be measured by Near-infrared spectroscopy, is lowered in hypoxia. It remains unclear whether CF intake can influence cerebral oxygenation and perfusion in hypoxic conditions and whether CF intake could (partially) counteract hypoxia-induced cognitive impairments. Therefore, the first aim of this study was to investigate whether cognitive function and prefrontal oxygenation during a mental demanding task will be impaired by hypoxic conditions (3000m altitude; 14.3% O2) and whether these impairments can be partially restored by subchronic CF intake (7 days, 900 mg/day). Hypoxia also impairs physical performance. Hypoxia-induced reductions in cerebral oxygenation may favour central fatigue, i.e. the failure of the central nervous system to excite the motoneurons adequately, hence impairing exercise performance in hypoxic conditions. Since hypoxia also impairs oxygen delivery to muscle tissue, the decreased oxygen supply to and impaired oxidative energy production in the exercising muscle is a second factor negatively affecting exercise performance. Besides the aforementioned effects of altitude on O2 delivery, hypoxia also results in increased oxidative stress. Oxidative stress refers to the imbalance between prooxidant and antioxidant levels in favor of prooxidants in cells and tissues and can result from diminished antioxidant levels or increased production of reactive oxygen species. The latter can be induced by both exhaustive exercise and high altitude. Since oxidative stress can be counteracted by CF, we also aim to investigate how markers of oxidative stress can be affected by CF intake by exercise in hypoxia. Therefore, the second aim of this study was to investigate possible beneficial effects of CF intake on changes in cerebral and muscle vasoreactivity and oxidative stress during exercise in hypoxia and its implications on exercise performance.
The purpose of this piece of research is to assess the effect of altitude on the clinical evolution of ARDS. For this purpose, patients who live and receive care at sea level are compared with those who live and receive care at high altitudes. For reasons of convenience, a cut-point of 1500 meters above sea level was chosen. In addition to this, it will be sought to assess whether adjusting the cut-points for the severity categories of ARDS improves the ability to predict some adverse events, by comparison with unadjusted cut-points. The results of this research will probably be disruptive, and will provide the first information yet about the effect of altitude on ARDS; they will therefore be of great interest for the international scientific community and for the direct care of patients. A high bibliometric impact is to be expected.