Blood Oxygenation (blood + oxygenation)

Distribution by Scientific Domains

Terms modified by Blood Oxygenation

  • blood oxygenation level dependent

  • Selected Abstracts


    Perfusion MR imaging with pulsed arterial spin-labeling: Basic principles and applications in functional brain imaging

    CONCEPTS IN MAGNETIC RESONANCE, Issue 5 2002
    Yihong Yang
    Abstract Basic principles of the arterial spin-labeling perfusion MRI are described, with focus on a brain perfusion model with pulsed labeling. A multislice perfusion imaging sequence with adiabatic inversion and spiral scanning is illustrated as an example. The mechanism of the perfusion measurement, the quantification of cerebral blood flow, and the suppression of potential artifacts are discussed. Applications of the perfusion imaging in brain activation studies, including simultaneous detection of blood flow and blood oxygenation, are demonstrated. Important issues associated with the applications such as sensitivity, quantification, and temporal resolution are discussed. © 2002 Wiley Periodicals, Inc. Concepts Magn Reson 14: 347,357, 2002 [source]


    Chronological analysis of physiological T2* signal change in the cerebrum during breath holding

    JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2001
    Kazuyoshi Nakada MD
    Abstract The purpose of this study was to examine which physiological factors affect cerebral T2* signal intensity (SI) during breath holding (BH) (apnea after inspiration and breathing after expiration) in normal volunteers. We examined SI changes caused by anoxic gas inhalation, by respiratory movements, and by BH. High-speed echo planar images (EPI) showed changes in SI that could be divided into five phases. Reports indicate that SI changes induced by BH are due to the effects on the magnetic susceptibility of deoxygenated hemoglobin (deoxyhemoglobin (dHb)) and to hypercapnia, but these reports could not fully explain the observed five phases. In addition to deoxyhemoglobin susceptibility and hypercapnia, we found that respiratory movements play a third critical role in modifying SI by affecting blood flow into the region of interest (ROI), as judged from right carotid artery flow. Consequently, we propose that the physiological SI changes induced by BH are derived from blood oxygenation, hypercapnia, and respiratory movements. J. Magn. Reson. Imaging 2001;13:344,351. © 2001 Wiley-Liss, Inc. [source]


    The effects of activated protein C and prostacyclin on arterial oxygenation and protein leakage in the lung and the gut under endotoxaemia in the rat

    ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2008
    M. DUBNIKS
    Background: Based on the anti-adhesive/anti-aggregatory and permeability-reducing properties of activated protein C (APC) and prostacyclin (PGI2), we analysed and compared these substances regarding their efficacy in counteracting transcapillary leakage of albumin in the lung and the gut, and in improving arterial oxygenation under a condition of inflammation. Methods: The randomized and blinded study was performed on 31 adult male Sprague-Dawley rats. Inflammation was induced by continuous infusion of Escherichia coli endotoxin (lipopolysaccharide, LPS). Six hours after the start of the LPS infusion (240,000 U/kg/h), a simultaneous infusion of saline (control group) or 8 ,g/kg/min of human recombinant APC or 2 ng/kg/min of PGI2 was started and continued for 24 h (n=8 per group). The study also included a sham group. Transcapillary leakage of albumin was measured from the ratio between tissue radioactivity [counts per minute (cpm)/g tissue] and actual amount of radioactivity given (cpm/g body weight of 125I-albumin). Oxygenation was assessed from arterial and central venous blood samples. Results: LPS induced albumin leakage in the gut and the lung, and impaired blood oxygenation. In the lung, the leakage was lower in the PGI2 group than in the APC and the control groups (P<0.05). In the gut, it was lower in the APC and the PGI2 groups than in the control group (P<0.05). Oxygenation was better in the APC and PGI2 groups than in the control group. Conclusion: Our data suggest that both APC and low-dose PGI2 are beneficial in LPS-induced inflammation in the rat, by reducing albumin leakage and improving blood oxygenation. [source]


    Low-dose prostacyclin in treatment of severe brain trauma evaluated with microdialysis and jugular bulb oxygen measurements

    ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 7 2000
    P.-O. Grände
    Background: The endogenous substance prostacyclin is a substance with the potential to improve microcirculation and oxygenation around contusions in the brain following a head trauma by its vasodilatory, antiaggregatory and antiadhesive effects. Microdialysis measurements of local concentrations of selected interstitial substances in the brain, and measurements of venous jugular bulb oxygenation reflecting overall brain oxygenation, might be useful to evaluate possible therapeutic effects of a specific therapy, such as treatment with prostacyclin. Methods: This case report study on six patients, of whom five were given prostacyclin, includes cerebral microdialysis measurements of interstitial lactate (n=5), pyruvate (n=3), glycerol (n=5) and glucose (n=4), and is combined with measurements of venous jugular bulb oxygenation in three of the patients. One microdialysis catheter was placed adjacent to a contusion, and in four of the patients another catheter was also placed in the contralateral less injured side for comparison. Low-dose prostacyclin infusion (0.5,1.0 ng kg,1 min,1) was started when lactate concentrations in the more injured side was raised at a constant level for more than 10 h. The study also includes one patient used as control to whom no prostacyclin was given. Results: Lactate was markedly lower in the less injured than in the more injured area of the brain. During the prostacyclin infusion elevated lactate and lactate/pyruvate ratio were reduced. Elevated glycerol decreased, a low glucose increased and jugular bulb blood oxygenation increased following start of prostacyclin. The control patient showed an increase in lactate and lactate/pyruvate ratio. Conclusion: The microdialysis data combined with the jugular bulb oxygenation data indicated that low-dose prostacyclin exerts effects compatible with improved oxygenation and reduced cell damage in the severely traumatised brain. [source]


    Attenuated prefrontal activation during a verbal fluency task in remitted major depression

    PSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 3 2009
    Go Okada md
    The aim of the present study was to investigate whether a functional abnormality in the left prefrontal cortex observed in patients with major depression performing a verbal fluency task is present after remission of depression. Functional magnetic resonance imaging was used to study changes in cerebral blood oxygenation in eight remitted patients with major depression and 10 healthy control subjects during a verbal fluency task. Compared to the control subjects, the patients had a reduced response in the left prefrontal cortex (middle frontal gyrus, Brodmann area 10). These findings suggest the presence of dysfunction in the left prefrontal cortex during remission in major depression. [source]


    Improved lung function after thoracocentesis in patients with paradoxical movement of a hemidiaphragm secondary to a large pleural effusion

    RESPIROLOGY, Issue 5 2007
    Lee-Min WANG
    Background and objectives: Previous studies have shown little or no improvement in pulmonary function and arterial blood oxygenation after therapeutic thoracocentesis. This study investigated changes in pulmonary function, arterial blood gases and dyspnoea after therapeutic thoracocentesis in patients with paradoxical movement (PM) of a hemidiaphragm due to pleural effusion. Methods: Twenty-one patients with pleural effusion and PM of a hemidiaphragm and 41 patients with pleural effusion but without paradoxical movement (NPM) were studied before and 24 h after thoracocentesis. Lung function measurements included lung mechanics, blood gas exchange and the Borg dyspnoea scale. Results: At thoracocentesis a mean of 1220 mL of pleural fluid was removed from the PM group and 1110 mL from the NPM group. Post-thoracocentesis the PM group showed small but significant improvement (P < 0.05) in FEV1 (63% vs 73%), FVC (67% vs 77%), PaO2 (66 mm Hg vs 73 mm Hg), A-a O2 gradient (38 mm Hg vs 30 mm Hg), and the Borg scale (5.1 vs 2.1). The NPM group showed no significant change in any parameter. Conclusions: Statistically significant improvement in pulmonary function following thoracocentesis was observed in patients with pleural effusion and PM of the hemidiaphragm. Patient selection may therefore explain the different outcomes of thoracocentesis reported in previous studies. [source]


    Growth plasticity of the embryonic and fetal heart

    BIOESSAYS, Issue 12 2009
    Jörg-Detlef Drenckhahn
    Abstract The developing mammalian heart responds to a variety of conditions, including changes in nutrient availability, blood oxygenation, hemodynamics, or tissue homeostasis, with impressive growth plasticity. This ensures the formation of a functional and normal sized organ by birth. During embryonic and fetal development the heart is exposed to various physiological and potentially pathological changes in the intrauterine environment which dramatically impact on normal cardiac function, tissue composition, and morphology. This paper summarizes the mechanisms employed by the embryonic and fetal heart to adapt to various intrauterine challenges to prevent or minimize postnatal consequences of impaired cardiac development. Future investigations of this growth plasticity might lead to new therapeutic strategies for the prevention of cardiac disease in postnatal life. [source]