Active clinical trials for "Hypoxia"

During exercise in conditions of low oxygen (termed hypoxia), such as mountaineering at high altitudes, the lung blood vessels constrict in an attempt to protect the body from the negative effects of hypoxia. It appears that this blood vessel constriction may limit the heart to pump blood during heavy exercise, leading to reductions in exercise performance. Inhaled nitric oxide is a drug that is known to relax the lung blood vessels. Inhaled nitric oxide has been used to relax lung blood vessels and improve exercise capacity in patients with chronic disease. It is unknown if similar improvements would be observed during exercise in healthy individuals when exposed to low levels of oxygen. The goal of this study is to determine if inhaled nitric oxide can relax the lung blood vessels and improve the heart's pumping ability during exercise in low oxygen conditions. Further, the investigators will determine if these improvements in lung blood vessel and heart function increase exercise performance. Participants will complete 6 sessions over a three week period where they will perform exercise challenges while breathing low levels of oxygen with and without inhaled nitric oxide. The low oxygen conditions will be comparable to being at an altitude of 14,000-17,000 feet. 17,000 feet would be equivalent to standing on the summit of King Peak in the Yukon (the 4th tallest mountain in Canada).

The goals of the present study are to evaluate whether the most common, and effective, treatment for acute mountain sickness (AMS), acetazolamide (AZ), has a negative, positive, or no influence on exercise performance, cognitive performance, or manual dexterity in young healthy subjects during simulated altitude exposure. AMS represents a serious challenge to the health and performance of the Warfighter who may need to rapidly deploy to high altitude. However, there have been concerns that AZ might alter or impair endurance exercise performance, and possibly fine motor skills. These would represent major limitations to the use of this drug in a Warfighter who has a specific timeframe in which to accomplish mission tasks. In the present project, we will use exposure to simulated altitude in the USARIEM hypobaric chamber to quantify the impact, if any, of AZ on endurance exercise performance following rapid ascent to 3500 meters (m) in unacclimatized lowlander volunteers. The study will be conducted using a randomized, single-blind, placebo-controlled crossover study design. Ten male and female volunteers will complete one orientation day, one VO2peak day, three days of familiarization testing at sea level (SL), then two rounds of experimental testing. Each round of experimental testing consists of six days including four days to establish baseline euhydration, followed by a 30 hour (hr) exposure to 3500 m. Volunteers will have a two week break between experimental testing rounds for washout of any effects of altitude acclimation. During one experimental round, volunteers will take two doses of AZ each day (Phase 1: 250 mg/dose,500 mg/day, Phase 2: 125 mg/dose, 250 mg/day) starting 48 hr prior to their altitude exposure and continuing for the 30 hr stay at high altitude. During the other experimental condition, volunteers will be given a placebo at the same time points as the doses of AZ. Prior to altitude exposure, AMS will be evaluated and volunteers will then ascend to a simulated altitude of 3500 m, where they will remain for 30 hr. Volunteers will rest at altitude for an hr, after which they will complete an AMS questionnaire, resting ventilation measurements, provide a blood sample and complete cognitive and finger dexterity testing. Subjects will then perform 15 minutes (min) of steady state (SS) treadmill exercise at 40-45% of SL VO2peak and a 2 mile treadmill time trial (TT). Volunteers will stay overnight in the hypobaric chamber with research staff supervision. The following morning, metabolic and blood measurements will again be completed, after which volunteers will perform the exercise testing for a second time. Cognitive and finger dexterity testing will be performed before volunteers return to sea level (i.e., "descend" from the simulated altitude). The results of the proposed study will, for the first time, provide quantitative evidence regarding whether AZ treatment impairs endurance exercise performance in the context of a Warfighter-relevant endurance exercise task.

The study evaluated the effect of non-invasive positive pressure ventilation (NIPPV) to decrease the incidence of desaturation events in patients with severe obesity undergoing upper endoscopy.

The aim of the current study is to evaluate under blinded conditions, both in a simulated environment and during helicopter flight, the effect of a rapid (within 20 minutes) exposure to altitude (4000 m asl) on physiological parameters and selected cognitive domains, in providers operating in helicopter emergency medical service (HEMS) exposed to hypobaric hypoxia or to hypobaric normoxia (H0: cognitive effects under hypobaric hypoxia = cognitive effects under hypobaric normoxia). Simulated environment will allow to control different factors. The parallelism between a study branch conducted in a simulated environment and another one conducted under a real-life condition will allow to evaluate the additive effects on additional stressor factors (processive and systemic ones). Simulation branch: each participant will take part in three research sessions: a familiarization session and two experimental sessions in simulation facility called terraXcube (test 1 and 2). On test 1 and test 2 each group will be exposed twice to the simulated altitude of 4000 m asl (under hypobaric hypoxia or hypobaric normoxia conditions) according to the randomization protocol. Participants will perform the neurocognitive tests three times on each of the two tests: before the ascent (TC0), after 5 min from the end of the ascent (TC1) and after around 30 min (TC2), to investigate European Union Aviation Safe Agency (EASA) proposed recommendations. After completing each neurocognitive test session, participants will be asked to rate their performance using a visual analogue scales (VAS). All participants will wear the vital parameters monitoring system during the entire duration of the tests inside the chamber, as well as the cerebral oxygen saturation (ScO2) sensor. Samples will be collected by saliva, urine and/or capillary blood. The same schedule is repeated in each test session. In-field branch: each participant will take part in three research sessions: a familiarization session and two experimental sessions during helicopter flights (test 1 and 2). On test 1 and test 2 each group will be exposed twice to the altitude of 4000 m (under hypobaric hypoxia or hypobaric normoxia conditions) according to the randomization protocol. Participants will perform the neurocognitive test two times on each test: before the ascent (TC0), after around 5 min from the end of the ascent (TC1). After completing each neurocognitive tests, participants will be asked to rate their performance using a visual analogue scales (VAS). All participants will wear the vital parameters monitoring system during the entire duration of the tests. Samples will be collected. The same schedule is planned in each test session.

To investigate surgical mask use and high-intensity interval exercise across different environmental conditions.

This study is investigating the effects of oral ketone and sodium bicarbonate administration on physiological and metabolic parameters during cycling endurance exercise in hypoxia. Ketone body supplementation is commonly used among elite endurance athletes that also compete in the hypoxia (at altitude). To-date effects of ketones have only been investigated in normoxia and the data in hypoxia is lacking. Hence, we want to investigate the effect of oral ketone ester intake with and without additional sodium bicarbonate (NaHCO3) ingestion on i) blood-acid base balance and ii) exercise performance during prolonged exercise under hypoxic conditions. Information obtained via this study should provide valuable information with regard to optimisation of exercise training and athletic performance, and more importantly, provide pioneering insight on the metabolic and physiological responses to ketosis under hypoxic conditions.

It has been shown in in vitro and animal models that hypoxia can have pro-inflammatory effects and hyperoxia can have anti-inflammatory effects. The pro-inflammatory effect could be the result of activation of Hypoxia Inducible Factor, a transcription factor that is known to activate many cell systems aimed at cell survival, including the inflammatory response. The anti-inflammatory effects of hyperoxia could be the annihilation of Hypoxia Inducible Factor, but also a decrease in inflammation due to oxygen toxicity resulting in a decrease in clearance of pathogens. These effects have been sparsely studied in humans. Therefore, we hypothesize that hypoxia results in an increase in Hypoxia Inducible Factor in circulating leukocytes and increases inflammatory reactions, whereas hyperoxia decreases these reactions.

The nasopharyngeal oxygen (NPO) with Nose-close (NC) and Abdomen-compression (AC) technique may use for support or rescue asphyxiated infants during Flexible bronchoscopy.

A low level of oxygen in cancer cells makes them less likely to respond to chemotherapy and radiotherapy treatments. There is interest in using new drugs that improve the level of oxygen in tumours. Another approach would be to increase the radiotherapy dose to tumours with low oxygen levels. Before we can do this for patients with rectal cancer, we need to develop a reliable way of identifying areas of low oxygen within the rectal tumour. This will make us able to tell which patients may be suitable for such a change in their treatment. Traditionally, the level of oxygen in tumours is measured by inserting a needle into the tumour and measuring it directly. This is not possible in rectal cancer. This study has been designed to identify the best alternative method. We would like to do a blood test, take samples of cancer tissue and some detailed scans (18F-fluoromisonidazole (F-MISO) positron emission tomography, perfusion computed tomography, functional magnetic resonance imaging). The results of these tests will be compared to decide which gives us the most comprehensive and reliable information. Patients in Group A go straight to surgery. By looking for markers of low oxygen levels on the tumour that has been removed, we will be able to find out which of the study tests performed before the tumour was removed is the best. By repeating the scans we will be able to see how reliable they are and how much they change on a day to day basis. We think that tumours that still have low levels of oxygen after 8 to 10 doses of radiotherapy are the least likely to respond to treatment. Group B will have scans before radiotherapy treatment and after 8 to 10 doses of radiotherapy to see if we can identify the patients that have persistent low levels of oxygen.

A comparative study which compares the end-tidal carbon dioxide and oxygen saturation levels of patients during endoscopy which have used either the new oral-nasal oxygenating device (TwinGuard), or a standard bite block plus nasal cannulae using an equivalent flow rate of oxygen.