Active clinical trials for "Hypoxia"

For some upper ureteral and renal stones,ureteroscopic lithotripsy needs to be performed under general anesthesia with interrupted suspension of mechanical ventilation, which could result in hypercapnia and hypoxia. In this study, the investigators hypothesize that 10 cmH2O PEEP added to the respiratory circuit with 1 L/min 100% oxygen might extend the time of ventilation suspension but have no effect on carbon dioxide retention in blood.

Nowadays, most assisted reproduction laboratories attempt to maintain as much as possible ex vivo culture conditions comparable to those in vivo. Various culturing condition such as temperature and pH parameters have been adjusted according to in vivo values in order to improve in-vitro fertilization (IVF) outcomes. Embryos of most mammals, including that of humans, are not exposed to oxygen concentration higher than 8%. Thus, embryos and gametes should be kept in a low oxygen environment during manipulation in assisted reproduction treatment. Culturing embryos in low oxygen concentrations is now a general practice in IVF laboratories. However, there are still laboratory procedures when the oocytes/embryos are exposed to atmospheric oxygen. In most laboratories, oocytes retrieval is performed under atmospheric oxygen concentration. Oocyte is very sensitive to environmental changes, for instance, transient cooling to room temperature can cause irreversible disruption of the meiotic spindle in human oocytes and oocyte in vitro maturation can lead to the decline of energy metabolism in human oocytes. Whether oocyte exposed to atmospheric oxygen during oocyte retrieval has detrimental effect on embryo development and IVF outcomes is unknown. Previous studies showed that low oxygen tension during embryo culture improved implantation rate and clinical outcomes, but embryo quality was not affected. In other studies, embryo quality was improved but overall pregnancy was not affected. The reason for the discrepancies could be because the oxygen tension during oocyte/embryo manipulation was not under well control. For instance, oocyte retrieval, fertilization check and embryo grading were performed under atmospheric oxygen. It is difficult to predict how these factors negatively impact the IVF outcomes. In this project, the investigators hypothesize that lower oxygen tension during oocyte/embryo manipulation improves IVF outcomes.

The study presents an alternative method of tracheal dilatation in pediatric patients with acquired tracheal stenosis. Dilatation is performed by the use of balloon catheter connected with manometer, that is bronchoscopic guided into trachea in the stenotic area, through the wide canal of supraglottic device i-Gel. Every dilatation cession consists of three consequent tracheal balloon dilatations of maximum 3 minutes duration each, followed by 10-15minutes interval of controlled ventilation. The balloon is inflated for 60 seconds to reach predefined pressure, and then deflated. This method is minimal traumatic for tracheal mucosa, and application of several dilatation procedures every 2-3months, in pediatric patients with acquired tracheal stenosis, may lead to a relative reopening of trachea and recession of clinical symptoms.For the right performance of the dilatation procedure, patients receive general anesthesia with cessation of spontaneous ventilation. During procedure, controlled ventilation-oxygenation is impossible, because the i-Gel canal is occupied by bronchoscope and balloon catheter, so patients will remain apneic for a short period of time. For pediatric patients is important to perform proper preoxygenation prior to procedure, and to maintain oxygenation as long as possible during procedure. This is achieved by application of apneic oxygenation, through a small catheter, connected to high flow oxygen. Participants are exposed during first dilation to no oxygenation, while during second and third dilatation to apneic oxygenation. Aim of the study is to investigate primarily whether application of apneic oxygenation, in pediatric patients during tracheal balloon dilatation, maintains regional cerebral oxygen saturation rSO2 in significant higher levels, compared with no application of oxygenation. rSO2 levels are a sensitive index of oxygenation efficacy of the brain, accordingly this refers to a safe procedure. Secondary issues are whether application of apneic oxygenation maintains pulse oximetry SpO2 and artierial oxygen partial pressure PaO2 in higher levels, and what are the effects on arterial carbon dioxide partial pressure PaCO2 and on haemodynamic parameters (heart rate, blood pressure), compared with no application of apneic oxygenation.

The early assessment of new symptomatic drugs for Alzheimer disease remains difficult because of the lack of predictive end-point. The use of a battery including different parameters could improve this early development. In healthy volunteers, to test the reverse effect of symptomatic drugs, it is necessary to induce transient and reversible cognitive impairment and cerebral activity changes by a challenge test. In this context, a transient hypoxia could be relevant.

In general bronchoscopy is a safe procedure with low rate of complications. Indeed, contraindications to flexible bronchoscopy are mostly relative rather than absolute. This is the case of preexisting decreased blood oxygen levels which may be present in patients requiring further bronchopulmonary investigation. To avoid the deleterious effects of oxygen drops oxygen supplementation is recommended. The purpose of this study is to evaluate the efficiency and safety of oxygen supplementation obtained with the use of a high flow nasal cannula compared with a low flow nasal cannula during flexible bronchoscopy. Consecutive patients referred by their treating physician for bronchoscopy will be offered to take part in the study. Those who wish to participate and give their consent will be randomly assigned into one of two treatment groups (supplemental oxygen given via low flow nasal cannula or via high flow nasal cannula). Assignment to either treatment arm will not affect in any way the intended purpose of the bronchoscopy. All patients will be closely monitored during the procedure and 2 hours following its completion. Monitoring will be conducted, using strictly non-invasive measures.

The purpose of this study is to compare the feasibility, safety, efficacy and ease of performance of a video-assisted PCT (via an endotracheal tube embedded with a mini video-camera) with the standard ("blind") PCT technique.

This study will investigate the effects of ketone ester drinks on cognitive performance in hypoxia.

The aim of this study is to compare the psychophysiological effects of terrestrial altitude with a normobaric, hypoxic situation.

The study is a prospective field evaluation to assess the effects of the chronic Intermittent Hypoxia exposure in 12 healthy humans. Precisely, the study was designed to : Set up a new model of Chronic Intermittent Hypoxia (CIH) applied to healthy human. This CIH is mimicking the CIH undergone by patients suffering from Sleep Apnea Syndrome. Evaluate the cardiovascular effect of CIH. Neuronal and humoral sympathetic control, blood pressure control, vascular resistance. Evaluate the Sleep quality, the ventilation under exposure and the long terms effect on ventilation control of CIH (central and peripheral chemoreflex). Investigates the biological aspects of CIH exposure.

The purpose is to investigate how the adenosine affects the diameter regulation of retinal arterioles during changes in oxygen tension. A deeper understanding of the mechanisms involved in diameter regulation of retinal arterioles during changes in oxygen tension can be used to obtain a more detailed understanding of diseases where changes in the diameter regulation of retinal vessels are involved in the disease pathogenesis and possibly point to new therapeutic options for patients with retinal vascular disease, such as diabetic retinopathy and retinal vein thrombosis. Preliminary, a routine ophthalmological evaluation, measurement of blood pressure, and electrocardiogram will be preformed to insure that only healthy test persons are included in the study. The test persons will be randomly allocated to two groups, one group in which protocol 1 is followed by protocol 2, and the other group with the two protocols performed in the reverse order. Protocol 1: Using the DVA, a video recording will capture the diameter of retinal vessels and the changes occurring during stimulation with flickering light. The recording lasts 4.5 minutes and is preformed before and after intravenous injection of adenosine. Protocol 2: The procedures are similar to those of protocol 1 but are performed during breathing of a gas mixture with a reduced oxygen tension to 12,5 %, which results in a reduced oxygen saturation in the blood to 85-90 %.