Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of Oxygenation

  • adequate oxygenation
  • arterial oxygenation
  • blood oxygenation
  • cerebral oxygenation
  • extracorporeal membrane oxygenation
  • hyperbaric oxygenation
  • membrane oxygenation
  • muscle oxygenation
  • renal oxygenation
  • tissue oxygenation
  • tumor oxygenation

  • Terms modified by Oxygenation

  • oxygenation change
  • oxygenation index
  • oxygenation level dependent
  • oxygenation reaction
  • oxygenation saturation

  • Selected Abstracts


    Leonardo Dos Santos
    SUMMARY 1Because in ischaemia there is a critical lack of O2, it has been reasoned that increasing O2 delivery to the ischaemic myocardium could serve as adjunctive therapy for acute myocardial infarction (MI). Accordingly, in the present study, the effect of early hyperbaric oxygenation (HBO) on mortality and MI size after coronary occlusion was examined in rats. 2After coronary occlusion, male Wistar rats were randomly assigned to receive either HBO for 1 h in a hyperbaric chamber (100% O2 at 253 kPa; n = 106) or ambient O2 as the control (n = 111). The extent of myocardial necrosis was assessed (triphenyltetrazolium) immediately after treatment in the HBO (n = 50) and control (n = 47) groups. The remaining rats were evaluated 24 h after occlusion to enable calculation of MI size and mortality. 3Immediately after therapy, the size of the MI was significantly greater in the control group compared with that in the HBO group (40 ± 3 vs 27 ± 2% of the left ventricle (LV), respectively; P < 0.001). The 24 h mortality of control rats was higher than that of HBO rats (34 vs 16%, respectively; P = 0.02). Control rats that survived 24 h had a larger MI than did HBO rats that survived 24 h (40 ± 4 vs 29 ± 3% of the LV, respectively; P = 0.005). Furthermore, large necrotic areas (> 40% of the LV) were more frequent in control than HBO rats (55 vs 27% of infarcted hearts, respectively; P = 0.01). There was less pulmonary congestion observed in HBO rats compared with control rats. 4In conclusion, early therapy with HBO during the onset of an acute ischaemic event decreases the necrotic area and reduces acute mortality. These data support further investigation of HBO as an adjuvant therapy for acute MI. [source]


    Roger G Evans
    SUMMARY 1An improved understanding of the regulation of kidney oxygenation has the potential to advance preventative, diagnostic and therapeutic strategies for kidney disease. Here, we review the strengths and limitations of available and emerging methods for studying kidney oxygen status. 2To fully characterize kidney oxygen handling, we must quantify multiple parameters, including renal oxygen delivery (DO2) and consumption (VO2), as well as oxygen tension (Po2). Ideally, these parameters should be quantified both at the whole-organ level and within specific vascular, tubular and interstitial compartments. 3Much of our current knowledge of kidney oxygen physiology comes from established techniques that allow measurement of global kidney DO2 and VO2, or local tissue Po2. When used in tandem, these techniques can help us understand oxygen mass balance in the kidney. Po2 can be resolved to specific tissue compartments in the superficial cortex, but not deep below the kidney surface. We have limited ability to measure local kidney tissue DO2 and VO2. 4Mathematical modelling has the potential to provide new insights into the physiology of kidney oxygenation, but is limited by the quality of the information such models are based on. 5Various imaging techniques and other emerging technologies have the potential to allow Po2 mapping throughout the kidney and/or spatial resolution of Po2 in specific renal tissues, even in humans. All currently available methods have serious limitations, but with further refinement should provide a pathway through which data obtained from experimental animal models can be related to humans in the clinical setting. [source]

    Synthesis, Crystal Structure, and Catalytic Properties of Novel Dioxidomolybdenum(VI) Complexes with Tridentate Schiff Base Ligands in the Biomimetic and Highly Selective Oxygenation of Alkenes and Sulfides

    Abdolreza Rezaeifard
    Abstract Four novel dioxidomolybdenum(VI) complexes [MoO2(Lx)(CH3OH)] have been synthesized, using 2[(E)-(2-hydroxy-2-phenylethylimino)methyl]phenol derivatives as tridentate ONO donor Schiff base ligands (H2Lx) and MoO2(acac)2. A monoclinic space group was determined by X-ray crystallography from single-crystal data of a sample of these new complexes. The epoxidation of alkenes by using tert -butyl hydroperoxide and oxidation of sulfides to sulfoxides by urea hydrogen peroxide were efficiently enhanced with excellent selectivity under the catalytic influence these new MoVI complexes. The high efficiency and relative stability of the catalysts have been observed by turnover numbers and UV/Vis investigations. The electron-poor and bulky ligands promoted the effectiveness of the catalysts. [source]

    On the Reactivity of C(sp3),H ,-Bonds: Oxygenation with Methyl(trifluoromethyl)­dioxirane

    Rossella Mello
    Abstract The reactivity of C,H ,-bonds of a series of 2-substituted adamantanes 2 towards methyl(trifluoromethyl)dioxirane (1) shows a consistent dependence on the electron-withdrawing ability, either inductive or by resonance, of the substituent. The results are interpreted in terms of the ability of the substrate molecule to delocalize the electronic perturbation of the reacting center at the beginning of the reaction path. The model shows that the electronic demand from the reacting C,H ,-bond is transmitted along the substrate through a chain of hyperconjugative interactions, the relative intensities of which depend on the ,-bonds involved. The substrate molecule simultaneously provides positive and negative stabilizing hyperconjugative interactions to the reacting center, their balance defining the geometry of the system at the beginning of the reaction path. The model constitutes a new experimental approach to measurement of the perturbation induced by substituents with significant resonance contributions on an adjacent C,H ,-bond. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

    Tissue Oxygenation Does Not Predict Central Venous Oxygenation in Emergency Department Patients With Severe Sepsis and Septic Shock

    Anthony M. Napoli MD
    Abstract Objectives:, This study sought to determine whether tissue oxygenation (StO2) could be used as a surrogate for central venous oxygenation (ScVO2) in early goal-directed therapy (EGDT). Methods:, The study enrolled a prospective convenience sample of patients aged ,18 years with sepsis and systolic blood pressure <90 mm Hg after 2 L of normal saline or lactate >4 mmol, who received a continuous central venous oximetry catheter. StO2 and ScVO2 were measured at 15-minute intervals. Data were analyzed using a random coefficients model, correlations, and Bland-Altman plots. Results:, There were 284 measurements in 40 patients. While a statistically significant relationship existed between StO2 and ScVO2 (F(1,37) = 10.23, p = 0.002), StO2 appears to systematically overestimate at lower ScVO2 and underestimate at higher ScVO2. This was reflected in the fixed effect slope of 0.49 (95% confidence interval [CI] = 0.266 to 0.720) and intercept of 34 (95% CI = 14.681 to 50.830), which were significantly different from 1 and 0, respectively. The initial point correlation (r = 0.5) was fair, but there was poor overall agreement (bias = 4.3, limits of agreement = ,20.8 to 29.4). Conclusions:, Correlation between StO2 and ScVO2 was fair. The two measures trend in the same direction, but clinical use of StO2 in lieu of ScVO2 is unsubstantiated due to large and systematic biases. However, these biases may reflect real physiologic states. Further research may investigate if these measures could be used in concert as prognostic indicators. ACADEMIC EMERGENCY MEDICINE 2010; 17:349,352 © 2010 by the Society for Academic Emergency Medicine [source]

    Metalloporphyrin/Iodine(III)-Cocatalyzed Oxygenation of Aromatic Hydrocarbons

    Akira Yoshimura
    Abstract Hypervalent iodine species have a pronounced catalytic effect on the metalloporphyrin-mediated oxygenations of aromatic hydrocarbons. In particular, the oxidation of anthracene to anthraquinone with Oxone readily occurs at room temperature in aqueous acetonitrile in the presence of 5,20,mol% of iodobenzene and 5,mol% of a water-soluble iron(III)-porphyrin complex. 2- tert -Butylanthracene and phenanthrene also can be oxygenated under similar conditions in the presence of 50,mol% of iodobenzene. The oxidation of styrene in the presence of 20,mol% of iodobenzene leads to a mixture of products of epoxidation and cleavage of the double bond. Partially hydrogenated aromatic hydrocarbons (e.g., 9,10-dihydroanthracene, 1,2,3,4-tetrahydronaphthalene, and 2,3-dihydro-1H -indene) afford under these conditions products of oxidation at the benzylic position in moderate yields. The proposed mechanism for these catalytic oxidations includes two catalytic redox cycles: 1) initial oxidation of iodobenzene with Oxone producing the hydroxy(phenyl)iodonium ion and hydrated iodosylbenzene, and 2) the oxidation of iron(III)-porphyrin to the oxoiron(IV)-porphyrin cation-radical complex by the intermediate iodine(III) species. The oxoiron(IV)-porphyrin cation-radical complex acts as the actual oxygenating agent toward aromatic hydrocarbons. [source]

    Binuclear Iron(III) Phthalocyanine(,-Oxodimer)-Catalyzed Oxygenation of Aromatic Hydrocarbons with Iodosylbenzene Sulfate and Iodosylbenzene as the Oxidants

    Abstract Two binuclear iron(III) phthalocyanine-(,-oxodimer) complexes were tested in catalytic oxygenation reactions of several aromatic hydrocarbons using iodosylbenzene (PhIO)n or oligomeric iodosylbenzene sulfate [(PhIO)3SO3]n as the oxidants. Results of this study demonstrate that [(PhIO)3SO3]n is the most reactive oxygenating reagent that can be used as a safe and convenient alternative to the thermally unstable and potentially explosive iodosylbenzene. The pyridine-containing binuclear ,-oxobis{iron(III)-pyridino[3,4]-9(10),16(17),23(24)-tri- tert -butyltribenzoporphyrazine} is significantly more active as compared to the traditional ,-oxobis[iron(III)-2,9(10),16(17),23(24)-tetra- tert -butylphthalocyanine]. [source]

    Comparative Reactivity of Hypervalent Iodine Oxidants in Metalloporphyrin-Catalyzed Oxygenation of Hydrocarbons: Iodosylbenzene Sulfate and 2-Iodylbenzoic Acid Ester as Safe and Convenient Alternatives to Iodosylbenzene


    Abstract A comparative study of the reactivity of 2-iodylbenzoic acid isopropyl ester (IBX-ester), oligomeric iodosylbenzene sulfate [(PhIO)3,SO3]n, and iodosylbenzene in the oxygenation of anthracene in the presence of metal porphyrin or phthalocyanine complexes is reported. Results of this study demonstrate that oligomeric iodosylbenzene sulfate and the IBX-ester are the most reactive oxygenating reagents that can be used as a safe and convenient alternative to the thermally unstable and potentially explosive iodosylbenzene. [source]

    Prevention of Limb Ischemia and Edema During Peripheral Venoarterial Extracorporeal Membrane Oxygenation in Adults

    Claudio F. Russo M.D.
    The cannulation of the femoral vessels may be complicated by distal limb ischemia by arterial hypoperfusion and severe edema by venous obstruction. We describe a modified cannulation technique in order to prevent ischemia and edema of the inferior limb during VA-ECMO. [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

    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]

    A New Video Image Analysis System to Study Red Blood Cell Dynamics and Oxygenation in Capillary Networks

    MICROCIRCULATION, Issue 6 2005
    ABSTRACT Objective: The authors present a Measurement and Analysis System for Capillary Oxygen Transport (MASCOT) to study red blood cell (RBC) dynamics and oxygenation in capillary networks. The system enables analysis of capillaries to study geometry and morphology and provides values for capillary parameters such as diameter and segment length. It also serves as an analysis tool for capillary RBC flow characteristics, including RBC velocity, lineal density, and supply rate. Furthermore, the system provides a means of determining the oxygen saturation of hemoglobin contained within RBCs, by analysis of synchronized videotapes containing images at two wavelengths, enabling the quantification of the oxygen content of individual RBCs. Methods: Video recordings of RBC flow at two wavelengths, 420 nm (isosbestic) and 436 nm (oxygen sensitive), are made using a dual camera video microscopy system. The 420-nm recording is used to generate images based on the variance of light intensity fluctuations that help to identify capillaries in a given field of view that are in sharp focus and exhibit flow of individual RBCs separated by plasma gaps. A region of interest enclosing the desired capillary is defined and a fixed number of successive video frames at the two wavelengths are captured. Next a difference image is created, which delineates the RBC column, whose width is used to estimate the internal diameter of the capillary. The 420-nm images are also used to identify the location and centroid of each RBC within the capillary. A space,time image is generated to compute the average RBC velocity. Lineal density is calculated as the number of RBCs per unit length of a capillary segment. The mean optical density (OD) of each RBC is calculated at both wavelengths, and the average SO2 for each cell is determined from OD436/OD420. Results and Conclusions: MASCOT is a robust and flexible system that requires simple hardware, including a SGI workstation fitted with an audio-visual module, a VCR, and an oscilloscope. Since the new system provides information on an individual cell basis from entire capillary segments, the authors believe that results obtained using MASCOT will be more accurate than those obtained from previous systems. Due to its flexibility and ease of extension to other applications, MASCOT has the potential to be applied widely as an analysis tool for capillary oxygen transport measurements. [source]

    Hypercapnia: what is the limit in paediatric patients?

    A case of near-fatal asthma successfully treated by multipharmacological approach
    Summary We describe a case of prolonged severe hypercapnia with respiratory acidosis occurring during an episode of near-fatal asthma in an 8-year-old boy, followed by complete recovery. After admission to the intensive care unit, despite treatment with maximal conventional bronchodilatative therapy, the clinical picture deteriorated with evident signs of respiratory muscle fatigue. The child was sedated, intubated and mechanically ventilated. Magnesium sulphate, ketamine and sevoflurane were gradually introduced together with deep sedation, curarization and continuous bronchodilatative therapy. Ten hours after admission, arterial pCO2 reached 39 kPa (293 mmHg), pH was 6.77 and pO2 8.6 kPa (65 mmHg). Chest radiograph showed severe neck subcutaneous emphysema, with signs of mediastinal emphysema. No episode of haemodynamic instability was seen despite severe prolonged hypercapnia lasting more than 14 h. Oxygenation was maintained and successful recovery followed without neurological or cardiovascular sequelae. This case shows the cardiovascular and neurological tolerance of a prolonged period of supercarbia in a paediatric patient. The most important lesson to be learned is the extreme importance of maintaining adequate tissue perfusion and oxygenation during an asthma attack. The second lesson is that when conventional bronchodilators fail, the intensivist may resort to the use of drugs such as ketamine, magnesium sulphate and inhalation anaesthesia. In this context deep sedation and curarization are important not only to improve oxygenation, but also to reduce cerebral metabolic requirements. [source]

    Case Report: Extracorporeal Membrane Oxygenation in Nonintubated Patients as Bridge to Lung Transplantation

    K. M. Olsson
    We report on the use of veno-arterial extracorporeal membrane oxygenation (ECMO) as a bridging strategy to lung transplantation in awake and spontaneously breathing patients. All five patients described in this series presented with cardiopulmonary failure due to pulmonary hypertension with or without concomitant lung disease. ECMO insertion was performed under local anesthesia without sedation and resulted in immediate stabilization of hemodynamics and gas exchange as well as recovery from secondary organ dysfunction. Two patients later required endotracheal intubation because of bleeding complications and both of them eventually died. The other three patients remained awake on ECMO support for 18,35 days until the time of transplantation. These patients were able to breathe spontaneously, to eat and drink, and they received passive and active physiotherapy as well as psychological support. All of them made a full recovery after transplantation, which demonstrates the feasibility of using ECMO support in nonintubated patients with cardiopulmonary failure as a bridging strategy to lung transplantation. [source]

    Improved Survival After Liver Transplantation in Patients with Hepatopulmonary Syndrome

    S. Gupta
    Hepatopulmonary syndrome (HPS) is present in 10,32% of chronic liver disease patients, carries a poor prognosis and is treatable by liver transplantation (LT). Previous reports have shown high LT mortality in HPS and severe HPS (arterial oxygen (PaO2) ,50 mmHg). We reviewed outcomes in HPS patients who received LT between 2002 and 2008 at two transplant centers supported by a dedicated HPS clinic. We assessed mortality, complications and gas exchange in 21 HPS patients (mean age 51 years, MELD score 14), including 11/21 (52%) with severe HPS and 5/21 (24%) with living donor LT (median follow-up 20.2 months after LT). Overall mortality was 1/21 (5%); mortality in severe HPS was 1/11 (9%). Peritransplant hypoxemic respiratory failure occurred in 5/21 (24%), biliary complications in 8/21 (38%) and bleeding or vascular complications in 6/21 (29%). Oxygenation improved in all 19 patients in whom PaO2 or SaO2 were recorded. PaO2 increased from 52.2 ± 13.2 to 90.3 ± 11.5 mmHg (room air) (p < 0.0001) (12 patients); a higher baseline macroaggregated albumin shunt fraction predicted a lower rate of postoperative improvement (p = 0.045) (7 patients). Liver transplant survival in HPS and severe HPS was higher than previously demonstrated. Severity of HPS should not be the basis for transplant refusal. [source]

    The short-term effect of hyperoncotic albumin, given alone or with furosemide, on oxygenation in sepsis-induced Acute Respiratory Distress Syndrome

    ANAESTHESIA, Issue 3 2007
    M. Kuper
    Summary Two prospective non-randomised interventional case series were conducted consecutively at a single university hospital mixed intensive care unit, in patients with severe sepsis and acute respiratory distress syndrome. The first series describes the administration of 200 ml of 20% human albumin solution over 120 s in 13 patients, examining the hypothesis that raising plasma albumin should improve oxygenation. The second series describes the effect of administering 30 mg of furosemide intravenously along with the albumin in 15 patients, exploring whether this would produce more sustained improvement in oxygenation than albumin only. Oxygenation and haemodynamic parameters were measured for 4 h, during the period of peak oncotic effect. Hyperoncotic albumin given alone or with furosemide produced only transient improvement in oxygenation and haemodynamics, which was statistically significant only in the patients given albumin alone. Although the plasma albumin remained significantly elevated at 4 h in both series, no sustained improvement in oxygenation was seen. [source]

    Oxygenation during percutaneous tracheostomy

    ANAESTHESIA, Issue 4 2001
    D. Mitra
    No abstract is available for this article. [source]

    Prognostic Factors for Adult Patients Receiving Extracorporeal Membrane Oxygenation as Mechanical Circulatory Support,A 14-Year Experience at a Medical Center

    ARTIFICIAL ORGANS, Issue 2 2010
    Chinchun Lan
    Abstract Extracorporeal membrane oxygenation (ECMO) is a resource-consuming and highly invasive treatment. There were 1100 ECMO cases at the National Taiwan University Hospital between August 1994 and November 2008. Of these, 607 were adults (>18 years old) who received ECMO as mechanical circulatory support. In this study, patient characteristics and complications during the ECMO course were evaluated for their correlation with prognosis. The following factors were significantly different between survivors and nonsurvivors: age, coronary artery disease, diabetes mellitus, brain death, stroke during ECMO, the need for dialysis during ECMO, pre-ECMO infection, hypoglycemia, acidosis, alkalosis, the need for a distal perfusion catheter, and the amount of red blood cells transfused. Six independent predictors of mortality were identified: age, stroke, the need for dialysis during ECMO, pre-ECMO infection, hypoglycemia, and alkalosis. Our institution has comparatively extensive experience with adult patients, which may be quite different from other medical centers with respect to distribution of patient age. The findings should lead to better utilization of ECMO for adult patients in the future. [source]

    Hemocompatibility of a Miniaturized Extracorporeal Membrane Oxygenation and a Pumpless Interventional Lung Assist in Experimental Lung Injury

    ARTIFICIAL ORGANS, Issue 1 2010
    Ruedger Kopp
    Abstract Extracorporeal membrane oxygenation (ECMO) is used for most severe acute respiratory distress syndrome cases in specialized centers. Hemocompatibility of devices depends on the size and modification of blood contacting surfaces as well as blood flow rates. An interventional lung assist using arteriovenous perfusion of a low-resistance oxygenator without a blood pump (Novalung, Hechingen, Germany) or a miniaturized ECMO with reduced filling volume and a diagonal blood pump (Deltastream, Medos AG, Stolberg, Germany) could optimize hemocompatibility. The aim of the study was to compare hemocompatibility with conventional ECMO. Female pigs were connected to extracorporeal circulation for 24 h after lavage induced lung injury (eight per group). Activation of coagulation and immune system as well as blood cell damage was measured. A P value <0.05 was considered significant. Plasmatic coagulation was slightly activated in all groups demonstrated by increased thrombin-anti-thrombin III-complex. No clinical signs of bleeding or thromboembolism occurred. Thrombelastography revealed decreased clotting capacities after miniaturized ECMO, probably due to significantly reduced platelet count. These resulted in reduced dosage of intravenous heparin. Scanning electron microscopy of oxygenator fibers showed significantly increased binding and shape change of platelets after interventional lung assist. In all groups, hemolysis remained negligible, indicated by low plasma hemoglobin concentration. Interleukin 8 and tumor necrosis factor-, concentration as well as leukocyte count remained unchanged. Both devices demonstrated adequate hemocompatibility for safe clinical application, although a missing blood pump did not increase hemocompatibility. Further studies seem necessary to analyze the influence of different blood pumps on platelet drop systematically. [source]

    Emergency Use of Extracorporeal Membrane Oxygenation in Cardiopulmonary Failure

    ARTIFICIAL ORGANS, Issue 9 2009
    Matthias Arlt
    Abstract Severe pulmonary and cardiopulmonary failure resistant to critical care treatment leads to hypoxemia and hypoxia-dependent organ failure. New treatment options for cardiopulmonary failure are necessary even for patients in outlying medical facilities. If these patients are in need of specialized center treatment, additional emergency medical service has to be carried out quick and safely. We describe our experiences with a pumpless extracorporeal lung assist (PECLA/iLA) for out-of-center emergency treatment of hypercapnic respiratory failure and the use of a newly developed hand-held extracorporeal membrane oxygenation (ECMO) system in cardiac, pulmonary, and cardiopulmonary failure (EMERGENCY-LIFE Support System, ELS System, MAQUET Cardiopulmonary AG, Hechingen, Germany). Between March 2000 and April 2009, we used the PECLA System (n = 20) and the ELS System (n = 33) in adult patients. Cannulation was employed using percutaneous vessel access. The new hand-held ELS System consists of a centrifugal pump and a membrane oxygenator, both mounted on a special holder system for storing on a standard patient gurney for air or ground ambulance transfer. Bedside cannulation processes were uneventful. The PECLA System resulted in sufficient CO2 removal. In all ECMO patients, oxygen delivery and systemic blood flow could be restored and vasopressor support was markedly down. Hospital survival rate in the PECLA group was 50%, and 61% in the ECMO group. Out-of-center emergency treatment of hypercapnic pulmonary failure with pumpless extracorporeal gas exchange and treatment of cardiac, pulmonary, and cardiopulmonary failure with this new hand-held ECMO device is safe and highlyeffective. Patient outcome in cardiopulmonary organ failure could be improved. [source]

    Oxygenation,Ozonation of Blood During Extracorporeal Circulation: In Vitro Efficiency of a New Gas Exchange Device

    ARTIFICIAL ORGANS, Issue 9 2007
    Velio Bocci
    Abstract:, We have investigated the performance of a new gas exchange device (GED), named L001, specifically devised for the ozonation of human blood during extracorporeal circulation. This procedure, defined with the acronym "EBOO," means "extracorporeal blood oxygenation,ozonation." The innovative GED is made of microporous, ozone-resistant, polipropylene hollow fibers with an external diameter of 200 µm, a thickness of 50 µm, and a membrane surface area of 0.22 m2. The material is coated with phosphorylcholine on the external side in contact with the circulating blood, while a gas mixture, necessarily composed of medical oxygen and ozone (about 99 and 1%, respectively), flows inside the fibers in opposite direction. The new GED has been tested by using a buffered saline solution containing KI and by varying several parameters, and it has shown to be very versatile and efficient. Its main characteristics are minimal foreign surface contact, high gas transfer, and negligible priming volume. This device appears to be a practical, nontoxic, and rather inexpensive tool for performing ozonation of blood for already defined human diseases. [source]

    Mechanical Bridge with Extracorporeal Membrane Oxygenation and Ventricular Assist Device to Heart Transplantation

    ARTIFICIAL ORGANS, Issue 8 2001
    Shoei-Shen Wang
    Abstract: The aim of this study was to evaluate the effect of double bridges with extracorporeal membrane oxygenation (ECMO) and ventricular assist devices (VADs) in clinical heart transplantation. Between May 1994 and October 2000, 134 patients underwent heart transplantation at the National Taiwan University Hospital. Ten patients received ECMO or VAD support as bridges to transplantation. The ages ranged from 3 to 63 years. The indications included cardiac arrest under cardiopulmonary resuscitation in 2 and profound cardiogenic shock refractory to conventional therapy in 8 patients. Usually ECMO was first set up as rescue therapy. If ECMO could not be weaned off after short-term (usually 1 week) support, suitable VADs (HeartMate or Thoratec VAD) were implanted for medium-term or long-term support. Five patients received ECMO support as emergency rescue for 2 to 9 days, and then moved to Thoratec VAD for 8, 49, and 55 days, respectively, or centrifugal VAD for 31 days, or HeartMate VAD for 224 days. They all survived. The survival rate of double bridges with ECMO and VAD was 100%. In postcardiotomy cardiogenic shock, circulatory collapse from acute myocardial infarction or myocarditis, ECMO is the device of choice for short-term support. If heart transplantation is indicated, VADs should replace ECMO for their superiority as a bridge to heart transplantation. Our preliminary data of double bridges with ECMO and VAD revealed good results and were reliable and effective bridges to transplantation. [source]

    Islamic Radicalisation among North Africans in Britain

    Jonathan Githens-Mazer
    This article examines how symbols of Islamic repression and massacre affect radicalisation among North Africans living in the UK. It suggests that these symbols are an insufficient but necessary cause in the larger process of ,radicalisation', because they provide a basis for perceptions of injustice. In this context, myths, memories and symbols of colonial repression, contemporary repression of free political expression in North African states and current perceptions of western ,oppression' of Islam may be perceived as rationales for ,oxygenation'. Oxygenation here denotes exchanges among different Muslim communities throughout Britain which potentially facilitate terrorist networks. Oxygenation in turn contributes to ,blowback', here in the guise of perceptions among British Muslims of global oppression of the Umma, especially understood in light of the Iraqi and Afghani insurgencies. This article also explores how these symbols may be cultivated and disseminated at popular and elite levels. [source]

    2224: Oxygenation of the human retina

    Purpose Partial pressure of oxygen in the optic nerve and retina is regulated by the intraocular pressure and systemic blood pressure, the resistance in the blood vessels and oxygen consumption of the tissue. The PO2 is autoregulated and moderate changes in intraocular pressure, blood pressure or tissue oxygen consumption do not affect the retinal and optic nerve oxygen tension. Methods If the intraocular pressure is increased above 40 mmHg or the ocular perfusion pressure decreased below 50 mmHg the autoregulation is overwhelmed and the optic nerve becomes hypoxic. The levels of perfusion pressure that lead to optic nerve hypoxia in the laboratory correspond remarkably well to the levels that increase the risk of glaucomatous optic nerve atrophy in human glaucoma patients. Medical intervention can affect optic nerve PO2. Lowering the intraocular pressure tends to increase the optic nerve PO2, even though this effect may be masked by the autoregulation when the optic nerve PO2 and perfusion pressure is in the normal range. Results Carbonic anhydrase inhibitors increase retinal PO2 through a mechanism of vasodilatation and lowering of the intraocular pressure. Carbonic anhydrase inhibition reduces the removal of CO2 from the tissue and the CO2 accumulation induces vasodilatation resulting in increased blood flow and improved oxygen supply. This effect is inhibited by indomethacin but not other cyclo-oxygenase inhibitors. Conclusion Carbonic anhydrase inhibitors increase retinal blood flow and increase oxygen delivery. Glaucoma drugs and glaucoma surgery lower intraocular pressure, increase ocular perfusion pressure and blood flow. Demand of oxygen by retinal cells may be reduced through apoptosis and tissue atrophy, as well as active destruction of tissue by laser photocoagulation. [source]

    Oxone as an Inexpensive, Safe, and Environmentally Benign Oxidant for C,H Bond Oxygenation.

    CHEMINFORM, Issue 30 2006
    Lopa V. Desai
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

    Photosensitized Oxygenation of Diaryl Tellurides to Telluroxides and Their Oxidizing Properties.

    CHEMINFORM, Issue 48 2004
    Makoto Oba
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    ChemInform Abstract: Efficient Oxygenation of Hydrocarbons with Tetrabutylammonium Monopersulfate Catalyzed by Manganese meso-Tetraphenylporphyrin in the Presence of Imidazole.

    CHEMINFORM, Issue 27 2002
    Daryoush Mohajer
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Amavadine as a Catalyst for the Peroxidative Halogenation, Hydroxylation and Oxygenation of Alkanes and Benzene.

    CHEMINFORM, Issue 1 2001
    Patricia M. Reis
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    Reactivity of Molecular Dioxygen towards a Series of Isostructural Dichloroiron(III) Complexes with Tripodal Tetraamine Ligands: General Access to ,-Oxodiiron(III) Complexes and Effect of ,-Fluorination on the Reaction Kinetics

    Abstract We have synthesized the mono, di-, and tri-,-fluoro ligands in the tris(2-pyridylmethyl)amine (TPA) series, namely, FTPA, F2TPA and F3TPA, respectively. Fluorination at the ,-position of these nitrogen-containing tripods shifts the oxidation potential of the ligand by 45,70,mV per added fluorine atom. The crystal structures of the dichloroiron(II) complexes with FTPA and F2TPA reveal that the iron center lies in a distorted octahedral geometry comparable to that already found in TPAFeCl2. All spectroscopic data indicate that the geometry is retained in solution. These three isostructural complexes all react with molecular dioxygen to yield stable ,-oxodiiron(III) complexes. Crystal structure analyses are reported for each of these three ,-oxo compounds. With TPA, a symmetrical structure is obtained for a dicationic compound with the tripod coordinated in the ,4N coordination mode. With FTPA, the compound is a neutral ,-oxodiiron(III) complex with a ,3N coordination mode of the ligand. Oxygenation of the F2TPA complex gave a neutral unsymmetrical compound, the structure of which is reminiscent of that already found with the trifluorinated ligand. On reduction, all ,-oxodiiron(III) complexes revert to the starting iron(II) species. The oxygenation reaction parallels the well-known formation of ,-oxo derivatives from dioxygen in the chemistry of porphyrins reported almost three decades ago. The striking feature of the series of iron(II) precursors is the effect of the ligand on the kinetics of oxygenation of the complexes. Whereas the parent complex undergoes 90,% conversion over 40,h, the monofluorinated ligand provides a complex that has fully reacted after 30,h, whereas the reaction time for the complex with the difluorinated ligand is only 10,h. Analysis of the spectroscopic data reveals that formation of the ,-oxo complexes proceeds in two distinct reversible kinetic steps with k1,10,k2. For TPAFeCl2 and FTPAFeCl2 only small variations in the k1 and k2 values are observed. By contrast, F2TPAFeCl2 exhibits k1 and k2 values that are ten times higher. These differences in kinetics are interpreted in the light of structural and electronic effects, especially the Lewis acidity at the metal center. Our results suggest coordination of dioxygen as an initial step in the process leading to formation of ,-oxodiiron(III) compounds, by contrast with an unlikely outer-sphere reduction of dioxygen, which generally occurs at negative potentials. [source]

    Fullerene-Promoted Singlet-Oxygen Photochemical Oxygenations in Glass-Polymer Microstructured Reactors

    Tommaso Carofiglio
    Abstract In this paper we report the fabrication of thiolene-based microstructured reactors (MRs) that have been specifically designed to include solid-supported reagents within the microchannels network. We propose a convenient solution to realize reversible press-fit, leak-proof interconnects that greatly simplify the MR coupling to the external environment such as capillary tubing, sample reservoirs and pumps. The MRs have been used to carry out the oxidation of ,-terpinene and methionine using [60]fullerene, covalently linked to Tentagel® and silica gel matrices, as a singlet oxygen sensitizer. High conversions have been observed for both substrates although, in the case of ,-terpinene, a partial photodegradation of the endo -peroxide product was detected. Interestingly, in the case of methionine, a quantitative conversion to the corresponding sulfoxides was achieved in about 40 seconds, using low-power, white LED illumination. The reaction time is considerably shorter when compared to the batch procedure that requires, for the same process, about one hour illumination and the use of a 300-W tungsten halogen lamp. [source]

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

    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]