Active clinical trials for "Hyperoxia"

Rational: Preoxygenation is a standard procedure before (deep) sedation in the ED. However, there is literature suggesting that too much oxygen can be harmful. One potential detrimental effect is a decrease in cardiac output due to coronary vasoconstriction. So far, it is unknown if this effect is rate dependent and if it also occurs after only a short period of hyperoxia, as patients experience during procedural sedation pre-oxygenation. Objective: To investigate if hyperoxia has a negative effect on Cardiac index (CI) in patients undergoing procedural sedation in the ED.

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.

Patients undergoing Open Cardiac Surgery will be randomized into two groups. Group I will be ventilated with 40% Fio2 during induction, surgery and in Postoperative care unit. Group II will be ventilated with 100% Fio2 during induction and with 60-70% ( determined according to the arterial blood gas sample results) during surgery and in Postoperative care unit. Hemodynamic parameters ( systolic arterial pressure, diastolic arterial pressure, heart rate ), Arterial blood gas samples ( PaO2, PaCO2, pH, Oxygen saturation, Lactate), and pre and post cardiopulmonary bypass Superoxide dismutase and malonyl aldehyde levels.

The inner retina is crucially dependent on an adequate retinal blood supply. When the retina becomes ischemic and hypoxic this results in severe vision loss due to retinal neovascularization. Measurement of retinal blood flow and retinal oxygenation is, however, still a difficult task. Information on retinal oxygenation is almost unavailable from human studies. In the present protocol the investigators propose a procedure allowing for the measurement of retinal blood flow, retinal oxygenation and retinal oxygen extraction by combining a number of innovative techniques. Specifically, retinal vessel diameters will be measured with a Retinal Vessel Analyzer, retinal blood velocities with bi-directional laser Doppler velocimetry and retinal oxygenation with spectroscopic evaluation of retinal fundus images. This will allow for the calculation of retinal oxygen extraction, a fundamental parameter of retinal function. Up to now, no data for retinal oxygen extraction are available in the literature.

Oxygen is the most widely prescribed therapy in the ICU (intensive care unit) and can save lives in critical patients. While the deleterious effects of hypoxia are apparent and must be actively avoided, hyperoxia also has adverse effects. These include systemic, coronary and cerebral vasoconstriction; decreased coronary blood flow; pulmonary atelectasis and increased free radicals. Despite these deleterious effects, hyperoxia is common and frequent in the ICU (from 22% to 74%). A recent meta-analysis published in "The Lancet" with more than 16,000 patients demonstrated an association between liberal oxygen therapy and mortality in critical patients. Other meta-analyses confirm its results with high quality data according to the authors. A randomized controlled trial published in "The New England Journal of Medicine" comparing liberal versus conservative oxygen therapy showed no difference in mechanical ventilation days and mortality (The ICU-ROX, 2019). However, the difference in PaO2 between the two groups was very small and the PaO2 in the liberal group did not exceed 100 mmHg. In any case, conservative oxygen therapy is safe for critical patients. The recommendations therefore recommend an oxygen saturation between 94-97% in critical patients and 88-92% in patients with COPD (Chronic Obstructive Pulmonary Disease) . However, to our knowledge, no study has described the incidence of hyperoxia in non-intubated patients in the intensive care unit.

The Oxygen Reserve Index (ORi) is a reference that could help clinicians with their assessments of normoxic and hyperoxic states by scaling the measured absorption information between 0.00 and 1.00. An ORi of 0.00 corresponds to PaO2 values of 100mmHg and below and an ORi of 1.00 corresponds to PaO2 values of 200mmHg and above. This is a prospective, non-blinded, non-randomized study of the Oxygen Reserve Index (ORi) in a clinical setting. It is designed to evaluate the correlations with ORi and changes in PaO2 and the potential use of ORi as an early warning of impending arterial oxygen desaturation.

We evaluated the prognostic role of the intraoperative arterial oxygen partial pressures (PaO2) on postoperative patient and graft survival in living donor kidney transplantations.

The iPROVE-O2 trial aims at comparing the efficacy of high and conventional FiO2 within a perioperative individualized ventilatory strategy to reduce the overall incidence of SSI.

Aim of the present study is to investigate the influence of hyperoxia on the protein expression using the differential analysis of protein expression in tissues (proteomics). In the study, blood and urine samples will be collected from participants who undergo a short term hyperoxia using 100% oxgen for 3 hours. Here, gel electrophoresis, protein separation and mass spectroscopy allow to identify affected proteins. Based on these results, different induction factors of proteins will be determined and then assessed using a bioinformatic network analysis regarding the cellular influence.

The primary aim of this project is to get further knowledge of the physiology of flight atelectasis and its prevention. We seek to: 1) assess whether low levels of positive pressure breathing can prevent atelectasis formation in humans during exposure to hyperoxia and +Gz-accelerations. 2) get further knowledge on the effects of hypobaria on regional ventilation and perfusion. A secondary aim is to evaluate the effect of anti G-trouser inflation on ventilation and regional perfusion.