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  • 1
    ISSN: 0304-8853
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1238
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 3
    ISSN: 1432-1238
    Keywords: Work of breathing ; Positive pressure respiration methods ; Lung disease ; Obstructive therapy ; Ventilator weaning ; Mechanical ventilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective Evaluation of low-level PEEP (5 cm H2O) and the two different CPAP trigger modes in the Bennett 7200a ventilator (demand-valve and flow-by trigger modes) on inspiratory work of breathing (Wi) during the weaning phase. Design Prospective controlled study. Setting The intensive care unit of a university hospital. Patients Six intubated patients with normal lung function (NL), ventilated because of non-pulmonary trauma or post-operative stay in the ICU, and six patients recovering from acute respiratory failure due to exacerbation of chronic obstructive pulmonary disease (COPD), breathing either FB-CPAP or DV-CPAP with the Bennett 7200a ventilator. Interventions The patients studied were breathing with zero end-expiratory pressure (ZEEP), as well as CPAP of 5 cm H2O (PEEP), with the following respiratory modes: the demand-valve trigger mode, pressure support of 5 cm H2O, and the flow-by trigger mode (base flow of 20 l/min and flow trigger of 2 l/min). Furthermore, Wi during T-piece breathing was evaluated. Measurements and results Wi was determined using a modified Campbell's diagram. Total inspiratory work (Wi), work against flow-resistive resistance (Wires), work against elastic resistance (Wiel), work imposed by the ventilator system (Wimp), dynamic intrinsic positive end-expiratory pressure (PEEPidyn), airway pressure decrease during beginning inspiration (Paw) and spirometric parameters were measured. In the NL group, only minor, clinically irrelevant changes in the measured variables were detected. In the COPD group, in contrast, PEEP reduced Wi and its components Wires and Wiel significantly compared to the corresponding ZEEP settings. This was due mainly to a significant decrease in PEEPidyn when external PEEP was applied. Flow-by imposed less Wi on the COPD patients during PEEP than did demand-valve CPAP. Differences in Wimp between the flow-by and demand-valve trigger models were significant for both groups. However, in relation to Wi these differences were small. Conclusion We conclude that the application of low-level external PEEP benefits COPD patients because it reduces inspiratory work, mainly by lowering the inspiratory threshold represented by PEEPidyn. Differences between the trigger modes of the ventilator used in this study were small and can be compensated for by the application of a small amount of pressure support.
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  • 4
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have used a bovine papilloma virus (BPV) based mammalian cell expression vector consisting of the complete BPV genome and a human cytomegalovirus transcription unit for the production of soluble CD4. Mouse C-127 cells were transfected with vector DNA together with a selectable G418 resistance plasmid. Surviving clones were selected for high production using a solid phase ELISA based on the immobilization of supernatant-derived CD4 onto nitrocellulose paper and subsequent detection with anti-CD4 antibodies. The expressed protein was shown to bind HIV-gp120 and efficiently block HIV-1 infection in vitro. The possibility to use the above system for rapid production of defined glycoprotein fragments harboring defined functional regions, for the further elucidation of the functional role of CD4 in antigen presentation and cell to cell contact, and for possible intervention during HIV infection is discussed.
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  • 5
    ISSN: 1432-055X
    Keywords: Schlüsselwörter: Messung der Sauerstoffaufnahme – Methodenvergleichsstudie – Inverses Ficksches Prinzip – Indirekte Kalorimetrie – Intrapulmonaler Sauerstoffverbrauch ; Key words: Measurement of oxygen uptake – Method comparison study – Reversed Fick principle – Indirect calorimetry – Intrapulmonary oxygen consumption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract. Automated measurements of respiratory gas exchange recently became available for the determination of oxygen uptake (V˙O2) in critically ill patients. Whereas these metabolic gas monitoring systems (MBM) are assumed to measure total body V˙O2, the reversed Fick method in principle excludes intrapulmonary V˙O2. Previous clinical reports comparing V˙O2 measured by the reversed Fick principle (V˙O2  Fick) with V˙O2 measured by MBM (V˙O2  MBM) found that V˙O2  MBM was significantly greater than V˙O2  Fick. It was suggested that these differences between methods represent V˙O2 of pulmonary and bronchial tissue, as intrapulmonary V˙O2 had been estimated to account for 15% of total body V˙O2 in dogs with experimental pneumonia. The objective of this study was to compare V˙O2  Fick with V˙O2  MBM in patients with and without pneumonia and to assess the reproducibility of both methods in critically ill patients. Method. With institutional approval nine critically ill patients with acute pneumonia were studied under controlled mechanical ventilation. The diagnosis of pneumonia was based on respective changes of chest X-rays, body temperature 〉38 °C, and WBC counts 〉12,000/mm3. Inspiratory oxygen fractions (FIO2) ranged from 0.3 to 0.6; all patients routinely received opioids and hypnotics. Complete muscle relaxation was achieved during the periods of measurement to avoid sudden changes in V˙O2 due to shivering or involuntary movements. Arterial and pulmonary-arterial blood samples were drawn simultaneously after aspiration of the sevenfold catheter dead space. Measurements of haemoglobin concentration (Hb), fractional oxygen saturation (SO2), and O2 partial pressure (PO2) were performed by use of a calibrated haemoximeter and blood gas analyser, respectively; 2×5 thermodilution measurements of cardiac output (CO) were spread randomly over the respiratory cycle for each determination of V˙O2  Fick. To minimise systematic errors of CO measurements, the CO computer was calibrated in an extracorporeal model using an electromagnetic flowmeter. Calculations of V˙O2  Fick were based on an oxygen binding capacity of 1.39 ml/g Hb. Simultaneous measurements of V˙O2  MBM were obtained by use of a Datex Deltatrac MBM that had been validated in vitro with a gas dilution model of respiratory gas exchange. Calibration of the MBM was performed prior to each measurement. Gas supply of the respirator was provided by an external high-precision mixing device to reduce errors in V˙O2 measurements that may arise from short-term oscillations in FIO2. All patients with pneumonia were studied on three consecutive days; thus, measurements from 27 days could be analysed. On each day two sets of measurements were performed at an interval of 60 min to assess the reproducibility of differences between methods. During each set of measurements duplicate blood samples were drawn twice, before and after thermodilution measurements of CO, to evaluate the short-term repeatability of V˙O2  Fick. The beginning and the end of each set of measurements were marked in the computer record of the MBM to assess the respective repeatability of V˙O2  MBM. Fifty control measurements were performed in ten patients undergoing major neurosurgical procedures. None of these patients exhibited signs of pulmonary infection. Except for the number of repeated measures, all V˙O2 measurements were obtained in the same way as in the study group. Descriptive statistical analysis was performed according to Bland and Altman; comparisons between methods were done by multivariate analysis of variance for repeated measures. Results. Neither in the study group nor in the control group could a significant difference between methods be demonstrated. In patients with pneumonia the mean difference between methods (V˙O2  Fick−V˙O2  MBM) was 15.2 ml/min (4.2%); the double standard deviation of differences (2 SD) was 59.2 ml/min (19.2%). Control patients exhibited a mean difference of 7.2 ml/min (3.1%); 2 SD was 41.1 ml/min (20.4%). Duplicate determinations of V˙O2  Fick and V˙O2  MBM within one set of measurements showed a repeatability coefficient (2 SD of differences between repeated measures) of 43.8 ml/min (13.2%) and 15.3 ml/min (5.1%), respectively. The large variation of duplicate measurements of V˙O2  Fick was caused rather by the variability of arteriovenous O2 content determinations than by the variability of CO measurements. Discussion. These results are in contrast to previous method comparison studies, which suggested that in infected lungs V˙O2 of pulmonary and bronchial tissue represents up to 15% of total body V˙O2. Since the mean differences between V˙O2  Fick and V˙O2  MBM did not differ between the two groups of patients, pulmonary infection did not seem to cause a considerable increase in intrapulmonary V˙O2. A minor effect of intrapulmonary V˙O2 on differences between methods cannot be excluded because of the variability of data. The poor repeatability of V˙O2  Fick measurements, however, seems to limit the use of method comparison studies for estimation of intrapulmonary V˙O2.
    Notes: Zusammenfassung. Automatisierte metabolische Monitorsysteme (MBM) ermöglichen nahezu kontinuierliche Messungen der Sauerstoffaufnahme (V˙O2) aus respiratorischen Gasen. Das inverse Ficksche Prinzip unterscheidet sich bei der Bestimmung der Gesamt-V˙O2 von diesen Verfahren insofern, als die intrapulmonale V˙O2 durch Lungen- und Bronchialgewebe nicht mit erfaßt wird. In der vorliegenden Untersuchung wurde daher unter besonderer Berücksichtigung der Methodenreproduzierbarkeit das inverse Ficksche Prinzip (V˙O2 Fick) mit V˙O2-Messungen aus respiratorischen Gasen (V˙O2  MBM) verglichen. Unter der Annahme, daß akute entzündliche Lungenerkrankungen zur Steigerung des intrapulmonalen Anteils der V˙O2 führen, wurden Vergleichsmessungen sowohl bei kritisch kranken Patienten mit akuter Pneumonie (n=9) als auch bei lungengesunden Kontrollpatienten (n=10) durchgeführt. Weder in der Studien- noch in der Kontrollgruppe fand sich eine signifikante Differenz zwischen den untersuchten Meßverfahren. Die mittlere relative Methodendifferenz V˙O2  Fick−V˙O2  MBM betrug +4,2% (2 SD=19,2%) in der Studiengruppe und +3,1% (2 SD=20,4%) in der Kontrollgruppe. V˙O2  Fick-Bestimmungen wiesen in Abhängigkeit von der Anzahl der gemittelten Blutanalysen eine zwei- bis dreifach schlechtere Reproduzierbarkeit auf als simultane V˙O2  MBM-Messungen. Die vorliegenden Befunde widersprechen der Hypothese, daß die intrapulmonale O2-Aufnahme bei Patienten mit pulmonalen Infektionen bis zu 15% der Gesamtkörper-V˙O2 repräsentiert. Ferner ist aufgrund der engen Übereinstimmung der systematischen Methodendifferenzen von Studien- und Kontrollpatienten nicht von einer klinisch bedeutsamen Steigerung der intrapulmonalen V˙O2 infolge von Pneumonien auszugehen.
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  • 6
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Gesamteiweiß ; Albumin ; Hypoalbuminämie ; Intensivpatienten ; Key words Total protein ; Hypoalbuminaemia ; Critically ill patients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract In clinical practice, the administration of supplementary albumin often depends on the measured plasma concentration of total protein (TPC). A TPC of less than 5 g/dl is generally accepted as an indication for albumin therapy, assuming an albumin concentration of less than 2.5 g/dl. However, a physiological relation between TPC and albumin cannot be expected in critically ill patients, and thus, measurement of TPC may be misleading as an indicator for the use of albumin. Therefore, we investigated the sensitivity and specificity of TPC testing for diagnosing hypoalbuminaemia requiring treatment. Methods. In this prospective study, 210 consecutive patients were included. Protein electrophoresis was performed three times a week; the second electrophoresis was selected for evaluation. Applied statistical analysis revealed the number of positive total protein tests indicating hypalbuminaemia requiring treatment (sensitivity) and the number of negative with tolerably reduced albumin concentrations (specificity). Results. Of the investigated patients, 27.6% had normal TPCs between 6.2 and 8.0 g/dl. In 81.9% of cases an albumin concentration below 3.5 g/dl was found, while 43 patients had a concentration below 2.5 g/dl. The sensitivity and specificity of TPC measurement for the diagnosis of clinically relevant hypoalbuminaemia (albumin concentration 〈2.5 g/dl) was calculated at different cutoff points for total protein. With a TPC of 6.0 g/dl, the sensitivity was 0.96 and the specificity 0.44. With a cutoff point of 5.0 g/dl, the sensitivity was reduced to 0.65 and specificity increased to 0.86. Finally, with a TPC of 4.0 g/dl sensitivity was 0.25 and specificity almost 1. Conclusions. Depending on the cutoff point for TPC, a relevant albumin requirement would frequently not be detected. In other cases, a need for albumin would be assumed from a reduced TPC even though the albumin concentration still exceeded 2.5 g/dl. Therefore, determination of TPC is not a suitable indicator of the need for albumin replacement. As a result, we suggest routine determination of albumin concentrations instead of TPC.
    Notes: Zusammenfassung In der klinischen Routine wird die Substitution von Humanalbumin häufig von der Gesamteiweißkonzentration abhängig gemacht, obwohl ein konstantes Verhältnis beider Variablen nicht immer zu erwarten ist. In der vorliegenden Untersuchung wurde die Sensitivität und Spezifität der Gesamteiweißbestimmung im Hinblick auf einen therapiebedürftigen Albuminmangel bei Intensivpatienten untersucht. Als Ergebnis zeigte sich, daß die Bestimmung der Gesamteiweißkonzentration mit erheblichen Fehleinschätzungen der Albuminkonzentration verbunden ist. Bei einer Interventionsschwelle von 5,00 g/dl Gesamteiweiß betrug die Sensitivität 0,64 und die Spezifität 0,86. Dagegen betrug bei einer Gesamteiweißkonzentration von 4,00 g/dl die Sensitivität nur noch 0,25, die Spezifität jedoch annähernd 1. Abhängig von der variablen Interventionsschwelle bezüglich der Gesamteiweißkonzentration wird einerseits ein relevanter Albuminbedarf häufig nicht erkannt. Andererseits kann in einigen Fällen eine unnötige Substitution erfolgen. Daher ist der Gesmteiweißtest zur Indikationsstellung der Albuminsubstitution nicht geeignet. Die direkte Bestimmung der Albuminkonzentration ist kostengünstig und routinemäßig durchführbar und sollte im Sinne einer rationalen Diagnostik und Therapie den Gesamteiweißtest ersetzen.
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  • 7
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Atemarbeit ; Beatmung ; Pressure Support Ventilation ; COPD ; Key words Pressure support ventilation ; Work of breathing ; Chronic obstructive pulmonary disease ; Mechanical ventilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract During pressure support ventilation (PSV), the timing of the breathing cycle is mainly controlled by the patient. Therefore, the delivered flow pattern during PSV might be better synchronised with the patient's demands than during volume-assisted ventilation. In several modern ventilators, inspiration is terminated when the inspiratory flow decreases to 25% of the initial peak value. However, this timing algorithm might cause premature inspiration termination if the initial peak flow is high. This could result not only in an increased risk of dyssynchronization between the patient and the ventilator, but also in reduced ventilatory support. On the other hand, a decreased peak flow might inappropriately increase the patient's inspiratory effort. The aim of our study was to evaluate the influence of the variation of the initial peak-flow rate during PSV on respiratory pattern and mechanical work of breathing. Patients. Six patients with chronic obstructive pulmonary disease (COPD) and six patients with no or minor nonobstructive lung pathology (control) were studied during PSV with different inspiratory flow rates by variations of the pressurisation time (Evita I, Drägerwerke, Lübeck, Germany). During the study period all patients were in stable circulatory conditions and in the weaning phase. Method. Patients were studied in a 45° semirecumbent position. Using the medium pressurization time (1 s) during PSV the inspiratory pressure was individually adjusted to obtain a tidal volume of about 8 ml/kg body weight. Thereafter, measurements were performed during five pressurization times (〈0.1, 0.5, 1, 1.5, 2 s defined as T 0.1, T 0.5, T 1, T 1.5 and T 2) in random order, while maintaining the pressure support setting at the ventilator. Between each measurement steady-state was attained. Positive end-exspiratory pressure (PEEP) and FIO2 were maintained at prestudy levels and remained constant during the study period. Informed consent was obtained from each patient or his next of kin. The study protocol was approved by the ethics committee of our medical faculty. Gas flow was measured at the proximal end of the endotracheal tube with a pneumotachometer (Fleisch no. 2, Fleisch, Lausanne, Switzerland) and a differential pressure transducer. Tracheal pressure (Paw) was determined in the same position with a second differential pressure transducer (Dr. Fenyves & Gut, Basel, Switzerland). Esophageal pressure (Pes) was obtained by a nasogastric balloon-catheter (Mallinckrodt, Argyle, NY, USA) connected to a further differential pressure transducer of the same type as described above. The balloon was positioned 2–3 cm above the dome of the diaphragm. The correct balloon position was verified by an occlusion test as described elsewhere. The data were sampled after A/D conversion with a frequency of 20 Hz and processed on an IBM-compatible PC. Software for data collection and processing was self-programmed using a commercially available software program (Asyst 4.0, Asyst Software Technologies, Rochester, NY, USA). Patient's inspiratory work of breathing Wpi (mJ/l) was calculated from Pes/volume plots according to the modified Campbell's diagram. Dynamic intrinsic PEEP (PEEPidyn) was obtained from esophageal pressure tracings relative to airway pressure as the deflection in Pes before the initiation of inspiratory flow Patient's additive work of breathing (Wadd) against ventilator system resistance was calculated directly from Paw/V tracings when Paw was lower than the pressure on the compliance curve. Two-way analysis of variance (ANOVA) was used for statistical analysis, followed by post hoc testing of the least significant difference between means for multiple comparisons. Probability values less than 0.05 were considered as significant. Results. COPD patients had significantly higher pressure support than control patients. With decreasing inspiratory flow, Wpi increased significantly in COPD patients. Additionally, the duct cycle (Ti/Ttot) significantly increased with decreased flow rates which resulted in a higher PEEPidyn compared to the baseline. At T 1.5 and T 2 with lower flow rates, the pre-set pressure support level was not achieved within inspiration in the COPD patients. Wadd increased significantly at T 1, T 1.5 and T 2 in COPD patients and at T 1.5 and T 2 in the control group. In one patient, premature termination of inspiration owing to high initial peak flow was corrected by adjustment of the inspiratory flow. Conclusion. Our results demonstrate that a decreased peak flow during PSV resulted in increased patient's work of breathing in COPD patients. During lower flow, the pre-set pressure support level was not attained and additional work had to be done on the ventilator system. Furthermore, the higher PEEPidyn during lower flow rates indicates a higher risk of dynamic pulmonary hyperinflation in patients with COPD. We conclude that the use of pressurization times ≥1 s to decrease inspiratory peak flow during PSV is of no benefit and should be avoided, particularly in COPD patients. However, in selected cases, slight decrease of inappropriately high peak flows might be useful for optimization of PSV setting to avoid premature termination of inspiration.
    Notes: Zusammenfassung Bei einigen Respiratoren kann unter Pressure Support Ventilation (PSV) der Inspirationsfluß (V˙ i ) durch Veränderung der Druckanstiegszeit variiert werden. Über den Einfluß des Inspirationsflußprofils unter PSV auf die Atemarbeit ist besonders bei Patienten mit chronischer Atemwegsobstruktion (COPD) kaum etwas bekannt. Wir untersuchten an 6 COPD-Patienten und 6 Patienten ohne Lungenerkrankung (Kontrollgruppe) die Effekte einer Variation von V˙ i unter PSV auf atemmechanische Variablen und die mechanische Atemarbeit. Unter individuell eingestellter Druckunterstützung wurde die Druckanstiegszeit in 5 Stufen verändert. Die Verlängerung der Druckanstiegszeit verminderte den initialen V˙ i in beiden Patientengruppen. Gleichzeitig stieg die Atemarbeit in der COPD-Gruppe bei verringertem V˙ i signifikant an. Eine Ursache hierfür war, daß bei den COPD-Patienten bei langsamen Druckanstiegszeiten die eingestellte Druckunterstützung nicht mehr erreicht wurde. Der langsamere V˙ i führte zu einer Verlängerung der Inspiration auf Kosten der Exspirationszeit. Dies verursachte bei COPD-Patienten eine unerwünschte Erhöhung des intrinsischen PEEP. Die Auswirkungen eines niedrigeren V˙ i unter PSV in der Kontrollgruppe waren klinisch nur wenig relevant. Unsere Ergebnisse zeigen, daß besonders bei Patienten mit COPD unter PSV hohe initiale Inspirationsflüsse zu bevorzugen sind, da ein niedriger Fluß die Patientenatemarbeit erhöht und eine dynamische Lungenüberblähung verstärkt. Allerdings konnte bei einem Patienten ein vorzeitiger Inspirationsabbruch aufgrund eines hohen Initialflusses durch Anpassung des Flußprofils korrigiert werden. In Einzelfällen kann daher eine Verlängerung der Druckanstiegszeit bis auf maximal 1 s sinnvoll sein.
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  • 8
    ISSN: 0930-9225
    Keywords: Schlüsselwörter Koronarchirurgie – Echokardiographie – Diastolische Ventrikelfunktion – Zeitkonstante der myokardialen Relaxation ; Key words Coronary bypass surgery – diastolic function –¶echocardiography – time constant of relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary There is evidence that diastolic function is a major determinant of overall cardiac performance. Intraoperative use of transesophageal echocardiography (TEE) enables Doppler measurement of mitral inflow pattern (E/A ratio). The E/A ratio is suggested to be a reliable index of changes in myocardial relaxation. In the present study we compared the time course of the E/A ratio and the time constant of myocardial relaxation (τ) assessed by direct left ventricular pressure recordings in patients before and after cardiopulmonary bypass (CPB). After ethical approval, 12 patients undergoing CABG surgery were studied. Measurements of the E/A ratio and τ were performed after induction of anesthesia (I), immediately prior to CPB with the pericardium open (II), 5 min after CPB (III), and after sternal closure (IV). Time constant of myocardial relaxation was calculated as the reciprocal value of the slope of the left ventricular dP/dt and left ventricular pressure plot. The E/A ratio was significantly decreased at the end of surgery (IV). In contrast, τ was increased immediately after CPB, but decreased after sternal closure (IV). Cardiac index and heart rate both increased after CPB.¶ The results of the present study demonstrate that diastolic dysfunction occurred immediately after CPB, as indicated by an increase in the time constant of myocardial relaxation. However, τ improved rapidly to pre-CPB values. The E/A ratio alone failed to detect the initial post-CPB alteration in left ventricular relaxation.
    Notes: Zusammenfassung Die Entwöhnung von der extrakorporalen Zirkulation (EKZ) stellt weiterhin eine kritische Phase während kardiochirurgischer Operationen dar. Es werden regelhaft myokardiale Funktionsstörungen beobachtet, wobei die diastolische Funktion nur eingeschränkt zu beurteilen ist. Die Einführung der transösophagealen Echokardiographie (TEE) ermöglicht dopplersonographisch die Differenzierung zwischen maximalem früh- (E) und spätdiastolischem (A) Blutfluß vom linken Atrium in den Ventrikel. Das Verhältnis von E zu A (E/A-Ratio) wird als ein Maß für die frühe diastolische Relaxation des Myokards angesehen. Wir untersuchten ob Änderungen der E/A-Ratio vor und nach Herz-Lungen-Maschine (HLM) mit Änderungen der durch direkte linksventrikuläre Druckmessung bestimmten Zeitkonstanten (τ) der frühen myokardialen Relaxation korrespondieren. Es wurden 12 koronarchirurgische Patienten mit eingeschränkter linksventrikulärer Funktion untersucht. Linksventrikulärer Druck und Druckabfallsgeschwindigkeit wurden mit einem Mikromanometerkatheter registriert. Zur Berechnung von τ wurde LVP gegen –dP/dt aufgetragen und mittels linearer Regressionsanalyse die Steigung der resultierenden Geraden bestimmt. Aus dem reziproken Wert der Steigung ergibt sich τ. Zur Bestimmung der E/A-Ratio wurde die Meßkammer des gepulsten Dopplers zwischen den Spitzen der Segel der Mitralklappe plaziert und der Bluteinstrom kontinuierlich bestimmt. Der mittlere arterielle, zentralvenöse Blutdruck und der pulmonalkapilläre Verschlußdruck sowie Herzfrequenz (HF) und Herzindex (HI) wurden nach Narkoseeinleitung (I), Eröffnung des Perikards (II), Entwöhnung von der HLM (III) und nach Sternalverschluß (IV) bestimmt. Die E/A-Ratio war am Ende der Operation (IV) signifikant erniedrigt. Im Gegensatz dazu war die Zeitkonstante der myokardialen Relaxation (τ) unmittelbar nach Abgang von der HLM signifikant (III) erhöht. HI und HF waren post-EKZ erhöht. Der nach Entwöhnung von der HLM gefundene Anstieg von τ ist hinweisend für eine diastolische Funktionsstörung, welche allerdings bereits am Punkt IV nicht mehr signifikant unterschiedlich zum Ausgangswert war. Die E/A-Ratio war hingegen unmittelbar post-HLM nicht signifikant erniedrigt.
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  • 9
    ISSN: 1432-055X
    Keywords: Schlüsselwörter: Fourniersche Gangrän – Sepsis – Schock ; Key words: Fournier's gangrene – Septic shock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract. Fournier's gangrene is a necrotising soft-tissue infection of the scrotum and perineal region caused by gram-negative and gram-positive Enterobacteriaceae. The disease is characterised by its unique appearance, its speed of onset, and its high mortality. Case report. A 26-year-old male presented to the emergency room complaining of a painful, tremendously swollen scrotum and penis (Fig. 1) that had developed within the past 24 h. Later, slurred speech, pallor, and hypotension were recognised, leading to the patient's admission to the intensive care unit. Suspecting a severe internal haemorrhage, vigorous volume therapy was started using crystalloids and colloids until blood and fresh frozen plasma were available. One hour later, septic shock was presumed and therapy augmented by IV antibiotics, tracheal intubation, and mechanical ventilation. Despite all efforts, the patients condition deteriorated rapidly and he died a few hours later due to multiple organ failure in septic shock. Postmortem, a perforated external hemorrhoidal node was found to be the primary focus of sepsis. Microbiologic cultures revealed Escherichia coli in blood and tissue samples. Discussion. Fournier's gangrene is a rare disease; nevertheless, its clinical picture has to be recognised immediately in order to provide appropriate treatment in time. It occurs predominantly in males after minor trauma, colorectal or urological disease, and perineal or abdominal surgery. Fournier's gangrene usually begins with itching and pain in the scrotal region followed by swelling and dark-blueish discolouration of the scrotum and penis, occasionally including the lower abdominal wall. Fever and chills are usually present. The illness progresses to severe prostration and septic shock with a mortality of 20% – 50%. Tissue cultures mostly reveal E. coli, gram-positive enterococci, Pseudomonas, Proteus, and various anaerobes. The treatment should include immediate radical surgical debridement, IV administration of broad-spectrum antibiotics, and cardiopulmonary support. Conclusion. The dramatic course of Fournier's gangrene requires early recognition, extensive surgical debridement, as well as intensive care treatment in order to prevent irreversible septic shock.
    Notes: Zusammenfassung. Die Fourniersche Gangrän manifestiert sich meist bei Männern mittleren bis höheren Lebensalters als nekrotisierende Fasciitis des äußeren Genitales. Kennzeichnend sind eine typische Anamnese mit progredienter, schmerzhafter Hodenschwellung und Fieber, ein oft explosionsartiger Beginn, der kaum verwechselbare makroskopische Aspekt und die hohe Mortalität infolge septischer Komplikationen. Der unter Umständen dramatische Verlauf der Erkrankung erfordert ein invasives chirurgisches und intensivmedizinisches Vorgehen. Die Entscheidung hierzu setzt die rasche Diagnose des seltenen Krankheitsbilds voraus. Wir berichten über einen jungen Patienten mit Fournierscher Gangrän, der wenige Stunden nach Aufnahme ins Krankenhaus an einem foudroyant verlaufenden septischen Schock verstarb.
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  • 10
    ISSN: 1432-055X
    Keywords: Schlüsselwörter: Intrinsischer PEEP – Externer PEEP – Beatmung ; Key words: Intrinsic PEEP – External PEEP – Mechanical ventilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract. Intrinsic positive end-expiratory pressure (PEEPi) occurring during mechanical ventilation depends on expiratory time constants, expiratory volume and expiration time as well as on external flow resistance (tubes, valves, etc.). It is not routinely determined in mechanically ventilated patients, but it is necessary to optimize respirator settings. The aim of the present study was the validation of an automated PEEPi determination method implemented in the respirator EVITA (Drägerwerke, Lübeck) in mechanically ventilated patients with acute lung failure. Patients. The method was validated in ten sedated, myorelaxed patients with respiratory insufficiency of different etiologies (five with restrictive, and five with obstructive pulmonary disease). PEEPi was determined using the volume constant ventilatory mode at ZEEP or at an external PEEP of 5 as well as 10 cm H2O. Method. PEEPi was first determined with the automated method implemented in the EVITA (five measurements at each end-expiratory pressure level; PEEPEvita). Steady-state was attained between each measurement. These values were compared to the results obtained with end-expiratory occlusion (external, computer-controlled valve in the inspiratory limb of the circuit) at the respective pressure levels (PEEPEEO). The average of five measurements at each PEEP level with each method was defined as PEEPi for the particular ventilatory situation. Gas flow was measured at the proximal end of the endotracheal tube with a heated pneumotachometer (Fleisch no. 2, Fleisch, Lausanne, Switzerland) and a differential pressure transducer. Tracheal pressure was determined in the same position with a further differential pressure transducer (Dr. Fenyves & Gut, Basel, Switzerland). After A/D conversion, data were sampled with a frequency of 20 Hz and processed on an IBM compatible PC. Software for data collection and processing as well as for control of the occlusion valve was self-programmed. For the statistical analysis we used the Mann-Whitney U-test or Wilcoxon signed-ranks test; a P value less than 0.05 was considered significant. Results. At the given respiratory setting and without PEEP patients with obstructive lung disease had a higher PEEPi (median: 6.4 cm H2O; range: 5.0 – 9.6 cm H2O) than those with restrictive pulmonary disease (median: 2.3 cm H2O; range: 0.8 – 3.0 cm H2O) (P〈0.05). Increasing external PEEP to 5 or 10 cm H2O significantly decreased the pressure difference between PEEPi and external PEEP (P〈0.05), but was unable to eliminate it completely. There was no statistically significant difference between PEEPEEO and PEEPEvita (P=0.43; Wilcoxon signed-ranks tests). Regression analysis showed a highly significant correlation between PEEPEEO and PEEPEvita values (r=0.985, P〈0.001; y=1.03x−0.18). Discussion. PEEPi occurs during ventilation in patients with obstructive and restrictive lung disease. The difference between external end-expiratory pressure and PEEPi decreases with increasing external PEEP. However, PEEPi may increase with increasing external PEEP in some instances. The reason for this may be that the PEEPi determined at the proximal end of the endotracheal tube represents only a mean value of different PEEPi values of various lung regions. Increasing external PEEP only partially alters this mean value due to an effect on PEEPi values lower than external PEEP. The PEEPi values measured by the EVITA respirator compared with classical end-expiratory occlusion with an external valve were nearly identical. Unfortunately, PEEPi measurement of the EVITA can only be performed during controlled and not during assisting (PSV, BIPAP etc.) ventilation. Optimal respirator settings require a knowledge of PEEPi (i.e., adaption of external PEEP for lowering the work of breathing in COPD patients or prolongation of the expiratory phase to avoid unwanted side effects of an occult PEEPi on the circulation). Since modern microprocessor-controlled respirators can easily be updated with the necessary equipment, measurement of PEEPi should be a part of routine ventilatory monitoring today.
    Notes: Zusammenfassung. Der intrinsische PEEP (PEEPi) wurde mit einer neuen automatisierten Meßmethode des Beatmungsgeräts EVITA (EVITA mit Software 13, Drägerwerke, Lübeck) bei 10 Patienten (5 restriktive, 5 obstruktive Lungenerkrankungen) unter maschineller Beatmung bestimmt. Diese Meßmethode wurde validiert gegen eine computergesteuerte end-exspiratorische Okklusion mit externem Ventil. Der PEEPi wurde mit beiden Methoden unter dem klinisch eingestellten volumenkonstanten Beatmungsmodus bei ZEEP (Umgebungsdruck) sowie externem PEEP von 5 und 10 cm H2O gemessen. Der Gasfluß wurde pneumotachographisch (Fleisch No. 2), der Trachealdruck mit einem Differenzdruckaufnehmer gemessen. Die Daten wurden digital aufgenommen und über einen Personalcomputer weiterverarbeitet. Bei ZEEP betrug der PEEPi bei obstruktiver Lungenfunktionsstörung 6,4 (5,0 – 9,6) cm H2O gegenüber 2,3 (0,8 – 3,0) cm H2O bei Restriktion (Median und Bereich; p〈0,05). Ein externer PEEP von 5 bzw. 10 cm H2O verringerte mit steigendem externen PEEP jeweils die Druckdifferenz zwischen PEEPi und externem PEEP signifikant, konnte diese aber nicht völlig eliminieren. Der Vergleich zwischen dem PEEPi-Meßmanöver der EVITA und einer "klassischen" end-exspiratorischen Okklusion mit einem externen Ventil ergab eine recht genaue Übereinstimmung mit hochsignifikanter Korrelation (r=0,985; y=1,03x−0,18). Leider ist das in der EVITA inkorporierte PEEPi-Meßmanöver nur unter kontrollierter Beatmung, nicht aber bei assistierenden Beatmungsformen (PSV, BIPAP etc.) durchführbar. Da moderne Ventilatoren leicht mit dem notwendigen Equipment auszurüsten wären, sollte die Messung des PEEPi zum klinischen Routinemonitoring unter der Beatmung gehören.
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