Active clinical trials for "Hypoxia"

The purpose of this study in patients with obstructive sleep apnoea (OSA) and concomitant patent foramen ovale (PFO) is to assess the impact of percutaneous PFO closure on nocturnal hypoxemia and apnea/hypopnea, pulmonary and systemic artery pressure, endothelial function and arterial stiffness.

This study will provide capnography monitoring during routine upper endoscopy and colonoscopy with moderate sedation in order to see if it improves safety.

The purpose of this study is to determine the efficacy and safety of nasal high flow oxygen therapy during diagnostic bronchoscopy.

On exposure to hypoxia (low oxygen) the normal response is for pulmonary arterial systolic blood pressure (PASP, blood pressure through the lungs) to increase. We have previously shown that raising iron by giving an infusion of iron into a vein reduces this pressure rise and that lowering iron by giving a drug that binds iron, magnifies this response. This is potentially a clinically important observation since iron-deficient people may be at increased risk of pulmonary hypertension if exposed transiently or permanently to hypoxia due to lung disease or residence at high altitude; furthermore if this were true then intravenous iron could be an important treatment in this patient group in the event of hypoxic exposure. The observed effects of iron on PASP are likely to be because iron levels affect oxygen sensing. Low iron levels make the body behave as if exposed to low oxygen by inhibiting the breakdown of the family of oxygen-sensing transcription factors, 'hypoxia inducible factor' or HIF. This includes one of the body's normal responses to low oxygen levels - raising blood pressure through the lungs. This study will answer the question (1) do iron-deficient volunteers have a greater rise in PASP with hypoxia than those who are iron-replete, and (2) does giving intravenous iron cause a greater reduction in the rise in PASP in those who are iron-deficient than iron-replete? The purpose of this study is not to test the safety or clinical efficacy of iron which is already known.

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.

Background and purpose: The purpose of this study is to investigate the effect of one acute exercise bout on tumor hypoxia in patients with localized prostate cancer undergoing radical prostatectomy. The primary hypothesis is that exercise reduces tumor hypoxia and that the reduction is greater in patients performing one acute high intensity exercise bout compared to no training controls. The investigators have not been able to identify any prior or current randomized trials investigating exercise and tumor hypoxia, and believe that such research is warranted and would be of great importance. Moreover there is a need for studies including biological measurements to allow a full assessment of the effect of exercise on diverse biomarkers and mechanistic pathways, which may influence cancer survival. Subjects: Patients with histologically verified prostate adenocarcinoma scheduled for radical prostatectomy at Urologic Department, Rigshospitalet, Copenhagen, Denmark. Methods: In this randomized controlled pilot study 30 patients with localized prostate cancer undergoing radical prostatectomy will be included and randomized 2:1 to either one single acute High Intensity Interval Training bout or usual care and no training the day prior to radical prostatectomy. All patients will undergo assessment at inclusion (baseline) and the day prior to surgery. Assessment includes: anthropometrics; blood pressure; resting hearth rate; hip and waist circumference, ECG, quality of life by self-report questionnaires; fasting blood sample measuring PSA (prostate specific antigen), cholesterol, triglycerides, insulin, c-peptide, HbA1c, glucose and inflammatory markers. All patients will receive one dose of pimonidazole hydrochloride (500 mg per m2 body surface) in order to quantify tumor hypoxia by pathological analyses after removal of the prostate. Biological tissue from tumor (primary prostate biopsies) will also be retrieved from the respective local pathological departments and from the perioperative prostate specimen and sent to protocol analyses.

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.

The overall goal of this project is to better understand the effect of intermittent hypoxia (IH) on sympathetic neuronal discharge patterns in humans, as well as mechanisms that mediate persistent sympathoexcitation with IH.

The study aims to evaluate the effects of acute hypobaric hypoxia on cognitive performance (H0: cognitive performance at 200 meters above sea level (asl) = cognitive performance at 3000 meters above sea level = cognitive performance at 5000 meters above sea level). Before participating in the study, each participant will respond to a questionnaire related to high altitude exposure (prior 3 months), as well as inclusion/exclusion criteria evaluation. On day 0, after the interview and signed informed consent, the participant will undergo a medical examination that will include a general objective examination. Participants will participate in a training on the emergency and safety procedures of the hypobaric hypoxia facility, as well as a refresh on cardiopulmonary resuscitation procedure. During the following two days (day 1 and 2) the study protocol will be executed (one test per day). The study protocol envisages: a basal cognitive test battery blind ascent in the hypobaric chamber to simulated altitude cognitive test battery 5 minutes of recorded chest compressions on dummies cognitive test battery blind descent in the hypobaric chamber. During the stay in the hypobaric hypoxic facility, each participant will be monitored in real time with the Equivital© medical monitoring device. Before and after the stay in the hypobaric hypoxic facility, a saliva sample will be collected, and psychological tests administered.

During alveolar hypoxia, for example at high altitude or in patients with respiratory disease, there is evidence to suggest that hypoxia-induced pulmonary hypertension might limit exercise performance. Intravenous iron supplementation has recently been shown to reverse pulmonary hypertension in healthy humans at high altitude, and to prevent pulmonary hypertension in volunteers exposed to hypoxia at sea level. The investigators hypothesized that intravenous iron supplementation would enhance exercise capacity during alveolar hypoxia.