View clinical trials related to Hypoxemia.
Filter by:Peripheral muscle oxidative function is altered in COPD(chronic obstrutive pulmonary disease) patients. Multiple factors could contribute to this dysfunction including chronic hypoxia and deconditioning (sedentarity). The evaluation of mitochondrial function is based on invasive method (muscle biopsy and in vitro respirometry) or magnetic resonance spectroscopy limited to small muscle groups. Recently, a non invasive method has been described using Near InfraRed Spectroscopy (NIRS). During arterial occlusion, muscle deoxygenation is only dependent of local oxygen consumption. The time constant recovery (k) of the deoxygenation during repeated ischemia periods has been shown to be correlated to measurements of maximal mitochondrial capacity. k is lower in COPD patients compared to smokers without bronchial obstruction. However, the influence of arterial hypoxia has never been studied precisely, no more than the confounding effect of deconditioning on k. So , the aim is to compare k in COPD patients with chronic hypoxemia (treated with long term oxygenotherapy, LTOT+ group) and patients without hypoxia, matched for their physical activity (LTOT- group). The hypothe is that k will be lower in LTOT+ group compared to LTOT- group and that short term O2 supplementation will improve it, which would suggest a muscle hypoxia. By contrast, O2 should not influence k in LOT- group, in whom it is mainly determined by muscle conditioning.
Background and rationale: A large multicenter randomized controlled trial demonstrated that in patients with hypoxemic non-hypercapnic respiratory failure treatment with nasal high flow oxygen (NHF) resulted in a reduction of the endotracheal intubation rate (38%) compared with noninvasive ventilation (NIV) delivered by facemask (50%) or with conventional oxygen therapy (47%), although the difference was not statistically significant. These results could be potentially explained by the physiological benefits provided by the NHF. However, one of the surprising findings of this study was that patients randomized to the facemask NIV group had a similar or even poorer outcome than oxygen alone. Interestingly, an observational study showed that in patients receiving facemask NIV for acute hypoxemia delivered tidal volumes were higher than expected (8.1-11.1 ml/kg predicted body weight), suggesting that NIV could potentially cause ventilator-induced lung injury resulting in worsening respiratory failure. We, therefore, plan a crossover physiologic study investigating the hypothesis that compared with NIV the treatment with NHF of patients with acute hypoxemic non-hypercapnic respiratory failure results in a more homogeneous distribution of tidal volume, and hence less ventilator-induced lung injury, as measured by electrical impedance tomography (EIT). Methods: This physiologic study will enroll 20 patients from the ICU at Toronto General Hospital in one year. Adult patients with acute hypoxemic non cardiogenic respiratory failure and PaO2:FiO2 ≤ 300 mmHg, respiratory rate > 25 breaths/minute, PaCO2 ≤ 45 mmHg and absence of clinical history of underlying chronic respiratory failure will be eligible. Patients that received invasive mechanical ventilation for > 48 hours in the same hospital admission, requiring immediate intubation, with hemodynamic instability (systolic arterial pressure < 90 mmHg after optimal fluid therapy), with Glasgow Coma Scale < 12, or contraindications to noninvasive ventilation and tracheostomy, will be excluded. After baseline assessment while receiving oxygen through facemask or nasal prongs, patients will receive in randomly assigned order NHF for 20 minutes and NIV for 20 minutes, in a crossover manner. EIT recordings, diaphragm ultrasound, and collection of blood samples for arterial blood gases will be performed at the end of each phase. Data analysis: The primary endpoint is the comparison of the EIT intra-tidal ventilation index between treatment with NHF and NIV. As secondary endpoints, we will determine whether NHF, in comparison to NIV, provides respiratory support with lower global inhomogeneity index (EIT), lower tidal volumes, reduces respiratory muscle effort (respiratory rate and diaphragmatic ultrasound), and improves gas exchange (oxygen saturation, PaO2:FiO2, PaCO2, RR).
Effects of acute intermittent hypoxia on brain function imaging and systemic inflammation Patients with obstructive sleep apnea (OSAS) may have neurological cognitive impairment. The reason is not clear. Intermittent hypoxia is one of the main manifestations of OSAS. The investigators hypothesize that acute intermittent hypoxia (AIH) can lead to abnormal metabolic activity in some regions of the brain, which may be associated with systemic inflammation. The investigators proposed in 12 to 15 cases of healthy volunteers, in the form of breathing in the nitrogen intermittently, were observed before and after AIH MRI diffusion tensor imaging (DTI) changes in brain regions and at the same time understand the inflammatory factors and the change of oxidative stress in the human body. The investigators look at the data from different brain regions of the brain DTI anisotropic score (FA), radial diffusion coefficient (RD), axial diffusion coefficient (AD) and peripheral blood interleukin-6 (IL - 6), interleukin-8 (IL - 8), interleukin-10(IL - 10), tumor necrosis factor alpha (TNF-α), Interleukin-1 beta (IL-1β), Leptin, high sensitivity reactive protein(hsCRP), Intercellular Adhesion Molecule 1(ICAM 1),Vascular cell adhesion protein 1(VCAM-1) , E-selectin, endothelin-1(ET - 1), 8-iso-PGF2α,3-nitrotyrosine(3-NT),hypoxia-inducible factor 1α(HIF 1α). Statistical data processing includes: the matching t test of the above indicators before and after AIH; The relationship between DTI and peripheral blood inflammatory factors was analyzed by single factor. Using DTI as the dependent variable, the peripheral blood inflammatory factor was analyzed by multifactor correlation. Ultimately, the effect of AIH on the brain's regional functions will be understood, and whether the effect is related to systemic inflammation.