View clinical trials related to Hypoxia, Altitude.
Filter by:This study analyses both Protein Expression and emotional alterations during hypobaric hypoxia in volunteers of different groups.
Patients with chronic lung diseases travelling by plane often suffer with symptoms related to lower oxygen levels they are exposed to while flying. Therefore, patients with respiratory conditions are routinely assessed to establish if they need supplemental oxygen in flight. A hypoxic altitude simulation test (HAST) is often part of this assessment and consists in having patients breathe a oxygen/nitrogen blend with a lower oxygen concentration compared to normal room air, simulating in-flight conditions. Oxygen levels are measured before and after the test through a blood sample (from the earlobe or an artery in the wrist) and with a finger probe. In-flight oxygen is required if the oxygen level in the blood is lower than 6.6 kPa. HASTs are time consuming, costly, and require a dedicated hospital appointment. Using historical data, the Investigators developed scores based on capillary blood gas (blood sample from the earlobe), diagnosis and sex to predict the outcome of the HASTs. The Investigators validated the proposed scores in a separate historic cohort of patients and showed it had good concordance with the HASTs results. In this study, the Investigators want to confirm prospectively if the score, based on blood results (venous and/or earlobe), can predict the outcome of the HASTs and therefore reduce the number of tests performed, travel time for patients, and costs for the NHS. All patients, aged 18 or older, who are having a HAST for clinical purposes at the cardio-respiratory lab at Leeds Teaching Hospital NHS Trust will be invited to take part in the study. The Investigators will record diagnosis, results of HAST and previous spirometry from the medical notes, perform a spirometry if not done in the previous 12 months and collect a blood sample (one tube, 4 mls). With these data, the Investigators will calculate the score and assess its agreement with the outcome of the HAST. Each participant's involvement in the study will last for approximately 90-120 minutes, which is the normal duration of a HAST. The Investigators aim to include up to 280 subjects in the study.
Background: Vaso-active polyphenols have been proposed to enhance cognitive performance. Oral administration with the non-flavonoid polyphenol, resveratrol, has been found to modulate cerebral blood flow (CBF); yet, this has not resulted in subsequent predicted benefits to cognitive performance in young, healthy samples. It has been argued that ageing populations who are noted suffer a reduction in CBF and cognition, may possess the subtle deficits to benefit from resveratrol administration. The use of hypoxia has been previously tested by this research group to mimic the decrease in cognitive functioning associated with ageing. Objectives: The current investigation aimed to further assess if a reduced fraction of inspired oxygen (12.7% FiO2) could provide an experimental model of aging in a young, healthy sample. Moreover, the current study also aimed to assess if resveratrol can attenuate the deficits elicited by the reduction in oxygen supply via increased CBF. Design: This repeated measures, double blind, placebo controlled, balanced design assessed the cognitive and CBF effects of resveratrol in hypoxia (equivalent to 4000 m above sea level) and normoxia (sea level). Methods: Twenty-four participants arrived fully fasted (except water) for 12 hours before completing a baseline measure of a cognitive task battery, and taking the treatment for the day (either 500 mg resveratrol or inert placebo). Following a 45 min absorption period, participants completed 3 full repetitions of a cognitive test battery. Changes in cerebral hemodynamics were measured by near-infrared spectroscopy throughout the full testing session.
1) Oxygen Transport in Normobaric versus Hypobaric Hypoxia. 2) The purpose of this study is to examine acute responses in arterial and muscle tissue oxygenation during incremental exercise in normobaric versus hypobaric hypoxia. 3) The participants in this study will consist of 12 recreationally active males and females between the ages of 19 and 45.Recreationally active is defined as participating in moderate to vigorous physical activity for 30 minutes at least 3 days per week.4) Subjects will complete an incremental cycle test to volitional fatigue in three conditions in a randomized counter-balanced order, normobaric normoxia (20.9% O2, 730 mmHg), normobaric hypoxia (14.3% O2, 730 mmHg) and hypobaric hypoxia (20.9% O2, 530mmHg). Two of the three trials will be conducted in an environmental chamber to simulate normobaric normoxia at 350 m (elevation of Omaha, NE) and normobaric hypoxia at 3094 m (elevation of Leadville, CO). The hypobaric hypoxia trial will be conducted in Leadville, Colorado at 3094 m. Trials will be separated by at least two days. Rating of perceived exertion, heart rate, blood oxygenation, respiration rate, muscle tissue oxygenation, and whole body gases will be analyzed during the trials. 5) There is no follow-up as a part of this study.
This study seeks to determine whether a simple, single intervention of Cetirizine / Zyrtec® use can improve exercise performance of active individuals when acutely exposed to altitude. For this project, healthy subjects will perform steady state and progressive work rate exercise, endurance performance time trials, and repeated sprint performance time trials in the laboratory at a simulated altitude of 3000m (9900ft) after dosing with 10 mg of Cetirizine or a placebo in a repeated measures design.
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.