View clinical trials related to Hyperoxia.
Filter by:The purpose of this study is to test the hypothesis that decreasing the inspired oxygen concentration during thoracic surgery requiring one lung ventilation will improve post-operative oxygenation.
Prospective observational study in 40 adult critically ill patients. Patients were eligible if they were mechanically ventilated with an FiO2 ≤0.5 and PaO2/FiO2 ≥200 mmHg and hemodynamically stable with a hemoglobin ≥9 g/dL, no acute bleeding or need for blood transfusions, no renal failure, no chronic obstructive pulmonary disease. Twenty patients (hyperoxia group) underwent a 2-hour exposure to normobaric hyperoxia (FiO2 1.0), 20 patients were evaluated as controls. Serum erythropoietin (EPO) was measured at baseline, 24h and 48h. Serum Glutathione (GSH) and reacting oxygen species (ROS) were assessed at baseline (t0), after 2 hours of hyperoxia (t1) and 2 hours after the return to baseline FiO2 (t2). Sidestream dark field videomicroscopy was applied sublingually to assess the microvascular response to hyperoxia. Near infrared spectroscopy with a vascular occlusion test was applied at t0, t1, t2.
This study is aiming at assessing the effect of inspired oxygen fraction during general anesthesia on children's lung mechanics and volume. More specifically, the temporal change in end-expiratory lung volume (EELV) and respiratory system resistance and elastance during the perioperative period will be characterized in order to define the the effect of high inspired fraction of oxygen on lung function.
Abdominal surgery commonly requires perioperative relaxation and therefore controlled mechanical ventilation. However, respiratory support can be associated with minor, yet clinically significant changes in blood gas content. The inadvertent hyperoxia (excessively high oxygen) and/or hypocapnia (excessively low carbon dioxide) can result in transient changes in cerebral blood flow and cognitive impair.
We made a fortuitous observation of periodic breathing in a healthy subject coming to our outpatient mountain medicine consultation at Avicenne hospital in Bobigny (France). During this consultation, subjects perform a hypoxia exercise test, which allows a good prediction of their risk factors for severe high altitude illnesses. Surprisingly, breath-by-breath recording of the ventilation signal showed a periodic breathing pattern, which increased when the subject started to exercise in hypoxic conditions and was maintained during normoxic exercise. Therefore, our objective was to confirm this observation in a retrospective study led in 82 subjects who passed this test. We tested the hypothesis that subjects with a brisk ventilatory response to hypoxia might show a more pronounced periodic pattern of ventilation, due to a higher gain of the chemoreceptor feedback loop. Then, our objective is to investigate the mechanisms involved in the periodic pattern in healthy subjects, as a function of exercise intensity, altitude intensity, role of peripheral and central chemoreceptors to O2 and CO2. Finally, we want to investigate the possible role of this ventilatory instability in patients with obstructive or central apneas.
Oxygen is a widely available gas that is cheap, easy to get and extensively used in medicine. From animal studies it has become apparent that increasing or lowering the degree of oxygen in the blood, the inflammatory response can be altered. We will investigate of this is also true in humans by increasing, lowering or keeping oxygen levels normal while giving healthy subjects a short inflammatory stimulus.
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.
Adequate perfusion and oxygenation is essential for the function of the inner retina. Although it is known that oxygen tension is very well autoregulated in the retina, the physiological mechanisms behind this regulation process are not fully explored. The development of new instruments for the non-invasive measurement of oxygen tension in retinal vessels now allows for the more precise investigation of these physiological processes. The current study seeks to evaluate the retinal oxygen saturation in healthy subjects while breathing different oxygen mixtures to achieve a hypoxic and a hyperoxic state.
This study aims to determine the effect of intermittent normoxic cardiopulmonary bypass (CPB) on inflammatory response, oxidative stress and myocardial reperfusion injury in adult patients undergoing valve replacement. The investigators hypothesized that nuclear factor kappa B (NFkB) was involved in regulating gene expression of myocardial inflammatory factor.
The purpose of this study is to determine how intraocular pressure responds to changes in the levels of carbon dioxide or oxygen that a healthy individual inspires.