Hyperoxia in extreme hemodilution

Intraoperative surgical blood loss is initially replaced by infusion of red cell-free, cristalloidal or colloidal solutions. When normovolemia is maintained the ensuing dilutional anemia is compensated by an increase of cardiac output and of arterial oxygen extraction. In the ideal case, a surgical blood loss can entirely be `bridged' without transfusion by intraciperative normovolemic hemodilution. However major blood loss results in extreme hemodilution and the transfusion of red blood cells may finally become necessary to increase arterial oxygen content and to preserve tissue oxygenation. When transfusion has to be started before surgical control of bleeding has been achieved, parts of the red blood cells transfused will get lost, thereby increasing intraoperative transfusion needs. Beside red blood cell transfusion, arterial oxygen content can be rapidly increased by ventilating the patient with 100% oxygen (hyperoxic ventilation), thus enhancing the amount of physically dissolved oxygen in plasma (hyperoxia). In experimental and clinical studies hyperoxic ventilation has emerged as a simple, safe and effective intervention to enlarge the margin of safety for hemodynamic compensation and tissue oxygenation in hemodiluted subjects experiencing major bleeding. The hyperoxia-associated microcirculatory dysregulation and impaired tissue oxygenation known to take place in the presence of a physiologic hemoglobin concentration are not encountered in hemodiluted subjects. Hyperoxic hemodilution i.e. the combination of intraoperative extreme hemodilution and hyperoxic ventilation may therefore be considered a cost-effective, safe and efficient supplement to reduce allogeneic transfusion during surgical interventions associated with high blood losses. The vast majority of the experimental and clinical investigations this new concept is based on was initiated and performed under the guidance of Prof. Konrad Messmer. Copyright (C) 2002 S. Karger AG, Basel

Diaspirin cross-linked hemoglobin fails to improve left ventricular diastolic function after fluid resuscitation from hemorrhagic shock

In severe hemorrhagic shock, left ventricular (LV) diastolic dysfunction is an early sign of cardiac failure due to compromised myocardial oxygenation. Immediate fluid replacement or, in particular, administration of a hemoglobin-based oxygen carrier (diaspirin cross-linked hemoglobin; DCLHb) improves myocardial oxygenation; therefore, positive effects on LV diastolic function could be expected. The effects of fluid resuscitation from severe hemorrhagic shock with DCLHb were investigated in 20 anesthetized domestic pigs. After generation of a critical left anterior descending coronary artery stenosis (narrowing of the artery until disappearance of reactive hyperemia after a 10-second complete vessel occlusion), hemorrhagic shock (mean arterial blood pressure 45 mm Hg) was induced within 15 min by controlled blood withdrawal and maintained for 60 min. Fluid resuscitation consisted of replacement of the plasma volume withdrawn during hemorrhage by infusion of either 10% DCLHb (DCLHb group, n = 10) or 8% human serum albumin (HSA) oncotically matched to DCLHb (HSA group, n = 10). After completion of resuscitation, an observation period of 60 min elapsed. Measurements of central hemodynamics, myocardial oxygenation, and LV Stolic function were performed at baseline, after induction of critical coronary artery stenosis, after 60 min hemorrhagic shock, immediately after resuscitation, and 60 min later. While 5 out of 10 animals treated with died within the first 20 min after fluid resuscitation from acute LV pump failure, all DCLHb-treated animals survived until the end of the protocol (p < 0.05). Despite superior myocardial oxygenation due to augmentation of the arterial O-2 content as well as of coronary perfusion pressure, no beneficial effects on LV diastolic function were observed after infusion of DCLHb. Peak velocity Of LV pressure decrease (dp/dt(min)) did not reveal significant differences between the two groups. Immediately after completion of fluid resuscitation with DCLHb, the time constant of LV diastolic relaxation (tau) was prolonged when compared with HSA-treated animals (p < 0.05), indicating retardation of early LV diastolic relaxation. Our data suggest that DCLHb fails to improve LV diastolic function after fluid resuscitation from severe hemorrhagic shock. However, positive effects on myocardial perfusion. and oxygenation result in a significant reduction of the mortality of severe hemorrhagic shock. Copyright (C) 2001 S.Karger AG, Basel

Chaos - No randomness in cardiac physiology

Struktur telinga manusia memiliki ciri yang stabil dan dapat diandalkan dibandingkan dengan wajah, karena struktur telinga tidak mengalami Perubahan secara proporsional pada peningkatan usia. Penelitian ini menggunakan ekstraksi ciri Zernike moment invariants (ZMI) untuk menentukan karakteristik daun telinga, sedangkan pengenalan telinga menggunakan Jaringan Syaraf Propagasi Balik (JSPB). Hasil eksperimen menunjukkan akurasi pengenalan telinga mencapai sebesar 96,66%

Quantifizierung postholsteinzeitlicher Subrosionen am Salzstock Gorleben durch statistische Auswertung von Bohrergebnissen

The Gorleben salt dome is actually investigated for its suitability as a repository for radioactive waste. It is crossed by a subglacial drainage channel, formed during the Elsterian glaciation (Gorleben channel). Some units of its filling vary strongly in niveau and thickness. Lowest positions and/or largest thickness are found above the salt dome. This is interpreted as a result of subrosion during the Saalean glaciation. The rate can be calculated from niveau differences of sediments formed during the Holsteinian interglacial. However, their position might have been influenced by other factors also (relief of the channel bottom, glacial tectonics, settlement of underlying clay-rich sediments). Their relevance was estimated applying statistical techniques to niveau and thickness data from 79 drillings in the Gorleben channel. Two classes of drillings with features caused by either Saalean subrosion or sedimentary processes during the filling of the Gorleben channel can be distinguished by means of factor and discriminant analysis. This interpretation is supported by the results of classwise correlation and regression analysis. Effects of glacial tectonics on the position of Holsteinian sediments cannot be misunderstood as subrosional. The influence of the settlement of underlying clay sediments can be estimated quantitatively. Saalean subrosion rates calculated from niveau differences of Holsteinian sediments between both classes differ with respect to the method applied: maximum values are 0,83 or 0,96 mm/a, average values are 0,31 or 0,41 mm/a.Der gegenwärtig auf seine Eignung als Endlager für radioaktive Abfälle erkundete Salzstock Gorleben wird von der elstereiszeitlichen subglaziären Geriebener Rinne gequert. Einige Einheiten der Rinnenfüllung weisen über dem Salzstock deutlich tieferes Niveau und teilweise höhere Mächtigkeit als daneben auf. Diese Unterschiede werden auf saaleeiszeitliche Subrosion zurückgeführt. Ihr Ausmaß kann aus den Niveauunterschieden der holsteinzeitlichen Ablagerungen abgeleitet werden. Zuvor muß allerdings der mögliche Einfluß anderer Faktoren (Relief des Rinnenbodens, Setzung von elstereiszeitlichen Tonserien, saaleeiszeitliche Eistektonik) auf deren heutiges Niveau geprüft werden. Dazu werden die Daten zu Tiefenniveau und Mächtigkeit der Einheiten der Rinnenfüllung für 79 Erkundungsbohrungen statistisch ausgewertet. Mit Hilfe von Faktoren- und Diskriminanzanalyse können die Bohrungen zwei Klassen zugeordnet werden, bei denen die heutigen Niveau- und Mächtigkeitsverhältnisse jeweils durch die Ablagerungsbedingungen in der Gorlebener Rinne bzw. saaleeiszeitliche Subrosion geprägt werden. Diese Deutung stützt sich auf klassendifferenzierte Korrelations- und Regressionsbetrachtungen. Andere Einflußfaktoren können danach ausgeschlossen (Eistektonik) bzw. bei der Berechnung von Subrosionsraten berücksichtigt werden (Setzung). Aus den Niveauunterschieden der Holstein-Serien zwischen beiden Klassen ergeben sich rechnerische saalezeitliche Subrosionsraten von je nach Berechnungsansatz maximal 0,83 bzw. 0,96 mm/a und im Mittel 0,31 bzw. 0,41 mm/a

Searching the ideal inhaled vasodilator: From nitric oxide to prostacyclin

Today, the technique to directly administer vasodilators via the airway to treat pulmonary hypertension and to improve pulmonary gas exchange is widely accepted among clinicians. The flood of scientific work focussing on this new therapeutic concept had been initiated by a fundamental new observation by Pepke-Zaba {[}1] and Frostell in 1991 {[}2]: Both scientists reported, that inhalation of exogenous nitric oxide (NO) gas selectively dilates pulmonary vessels without a concomittant systemic vasodilation. No more than another decade ago NO was identified as an important endogenous vasodilator {[}3] while having merely been regarded an environmental pollutant before that time. Although inhaled NO proved to be efficacious, alternatives were sought-after due to NO's potential side-effects. In search for the ideal inhaled vasodilator another group of endogenous mediators - the prostanoids - came into the focus of interest. The evidence for safety and efficacy of inhaled prostanoids is - among a lot of other valuable work - based on a series of experimental and clinical investigations that have been performed or designed at the Institute for Surgical Research under the guidance and mentorship of Prof. Dr. med. Dr. h.c. mult. K. Messmer {[}4-19]. In the following, the current and newly emerging clinical applications of inhaled prostanoids and the experimental data which they are based on, will be reviewed. Copyright (C) 2002 S. Karger AG, Basel

Estimation of inter-laboratory reference change values from external quality assessment data

It is common for patients to switch between several healthcare providers. In this context, the long-term follow-up of medical conditions based on laboratory test results obtained from different laboratories is a challenge. The measurement uncertainty in an inter-laboratory context should also be considered in data mining research based on routine results from randomly selected laboratories. As a proof-of-concept study, we aimed at estimating the inter-laboratory reference change value (IL-RCV) for exemplary analytes from publicly available data on external quality assessment (EQA) and biological variation. External quality assessment data of the Reference Institute for Bioanalytics (RfB, Bonn, Germany) for serum creatinine, calcium, aldosterone, PSA, and of whole blood HbA1c from campaigns sent out in 2019 were analysed. The median CVs of all EQA participants were calculated based on 8 samples from 4 EQA campaigns per analyte. Using intra-individual biological variation data from the EFLM database, positive and negative IL-RCV were estimated with a formula based on log transformation under the assumption that the analytes under examination have a skewed distribution. We estimated IL-RCVs for all exemplary analytes, ranging from 13.3% to 203% for the positive IL-RCV and - 11.8% to - 67.0% for the negative IL-RCV (serum calcium - serum aldosterone), respectively. External quality assessment data together with data on the biological variation – both freely available – allow the estimation of inter-laboratory RCVs. These differ substantially between different analytes and can help to assess the boundaries of interoperability in laboratory medicine

Comparison of regional blood flow values measured by radioactive and fluorescent microspheres

Fluorescent microspheres (FM) have become an attractive alternative to radioactive microspheres (RM) for the measurement of regional blood flow (RBF). The aim of the present study was to investigate the comparability of both methods by measuring RBF with FM and RM. Eight anaesthetised pigs received simultaneous, left atrial injections of FM and RM with a diameter of 15 mum at six different time points. Blood reference samples were collected from the descending aorta. RBF was determined in tissue samples of the myocardium, spleen and kidneys of all 8 animals. After radioactivity of the tissue samples was determined, the samples were processed automatically for measuring fluorescence using a recently developed filter device (SPU). RBF was calculated with both the isotope and spectrometric data of both methods for each sample resulting in a total of 10,512 blood flow values. The comparison of the RBF values yielded high linear correlation (mean r(2) = 0.95 +/- 0.03 to 0.97 +/- 0.02) and excellent agreement (bias 5.4-6.7%, precision 9.9-16.5%) of both methods. Our results indicate the validity of MS and of the automated tissue processing technique by means of the SPU. Copyright (C) 2002 S. Karger AG, Basel

The choice of the intravenous fluid influences the tolerance of acute normovolemic anemia in anesthetized domestic pigs

The correction of hypovolemia with acellular fluids results in acute normovolemic anemia. Whether the choice of the infusion fluid has an impact on the maintenance of oxygen (O2) supply during acute normovolemic anemia has not been investigated so far. Methods: Thirty-six anesthetized and mechanically ventilated pigs were hemodiluted to their physiological limit of anemia tolerance, reflected by the individual critical hemoglobin concentration (Hbcrit). Hbcrit was defined as the Hb-concentration corresponding with the onset of supply-dependency of total body O2-consumption (VO2). The hemodilution protocol was randomly performed with either Tetrastarch (6% HES 130/0.4, TS-group, n=9), Gelatin (3.5% urea-crosslinked polygeline, GEL-group, n=9), Hetastarch (6% HES 450/0.7, HS-group, n=9) or Ringer's solution (RS-group, n=9). The primary endpoint was the dimension of Hbcrit, secondary endpoints were parameters of central hemodynamics, O2-transport and tissue oxygenation. Results: In each animal, normovolemia was maintained throughout the protocol. Hbcrit was met at 3.7+/-0.6 g/dl (RS), 3.0+/-0.6 g/dl (HS P<0.05 vs. RS), 2.7+/-0.6 g/dl (GEL, P<0.05 vs. RS) and 2.1+/-0.4 g/dl (TS, P<0.05 vs. GEL, HS and RS). Hemodilution with RS resulted in a significant increase of extravascular lung water index (EVLWI) and a decrease of arterial oxygen partial pressure (paO2), O2-extraction ratio was increased, when animals of the TS-, GEL- and HS-groups met their individual Hbcrit. Conclusions: The choice of the intravenous (i.v) fluid has an impact on the tolerance of acute normovolemic anemia induced by acellular volume replacement. Third-generation Tetrastarch preparations (e.g., HES 130/0.4) appear most advantageous regarding maintenance of tissue oxygenation during progressive anemia. The underlying mechanism includes a lower degree of extravasation and favourable effects on microcirculatory function