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  • 1
    ISSN: 1432-1238
    Schlagwort(e): Adrenaline ; Glucose ; Amino acids ; Urea ; Stable isotopes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Objective To determine the magnitude and time course of adrenergic effects on metabolism in volunteers and possible implications for the use of sympathomimetics in the critically ill. Design Descriptive laboratory investigation. Subjects 7 volunteers. Intervention Primed continuous infusions of stable isotope tracers ([15N2]-urea, [6,6-D2]-glucose, [methyl-D3]-L-leucine, [15N]-L-alanine) were used. After isotopic steady state had been reached an infusion of adrenaline (0.1 μg/kg/min) was administered (4 h). Isotopic enrichment was measured using gas chromatography-mass spectrometry and the corresponding rates of appearance were calculated. Measurements and main results Glucose production increased from 14.1±1.2 to 21.5±2.0 μmol/kg/min (p〈0.05) after 80 min of adrenergic stimulation and then decreased again to 17.9±1.2 μmol/kg/min after 240 min. Leucine and ketoisocaproate (KIC) fluxes were 2.3±0.2 and 2.6±0.2 μmol/kg/min, respectively, at baseline and gradually decreased to 1.8±0.2 and 2.2±0.1 μmol/kg/min, respectively, after 240 min of adrenaline infusion (bothp〈0.05). Alanine flux increased from 3.7±0.5 to 6.9±0.9 μmol/kg/min (p〈0.05) after 80 min of adrenergic stimulation. Urea production slightly decreased from 4.8±0.9 to 4.3±0.8 μmol/kg/min during adrenaline (p〈0.05). Conclusions Adrenaline induced an increase in glucose production lasting for longer than 240 min. The decrease in leucine and KIC flux suggests a reduction in proteolysis, which was supported by the decrease in urea production. The increase in alanine flux is therefore most likely due to an increase in de-novo synthesis. The ammonia donor for alanine synthesis in peripheral tissues and the target for ammonia after alanine deamination in the liver remain to be investigated. These results indicate that adrenaline infusion most probably will not promote already enhanced proteolysis in critically ill patients. Gluconeogenesis is an energy consuming process and an increase may deteriorate hepatic oxygen balance in patients.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-1238
    Schlagwort(e): Noradrenaline ; Adrenaline ; Dopamine ; Oxygen consumption ; Blood pressure ; Heart rate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Objective To determine whether noradrenaline, adrenaline and dopamine have persistent on $$\dot VO_2 $$ and metabolism. Design Descriptive laboratory investigation. Setting Laboratory of the Department of Anaesthesiology at a University Hospital. Subjects 9 volunteers. Intervention $$\dot VO_2 $$ and the plasma concentration of glucose and free fatty acids were measured prior to and during a 4 h infusion of saline (control), noradrenaline (0.14 μg/kg min) adrenaline (0.08 μg/kg min) or dopamine (7 μg/kg min),n=9 each. $$\dot VO_2 $$ was measured using an open circuit gas exchange system. Measurements and main results $$\dot VO_2 $$ increased from 250±22 ml/min to 280±38 ml/min during noradrenaline, to 298±30 ml/min during adrenaline and to 292±39 ml/min during dopamine infusion. The plasma glucose concentration increased from 6.2±0.6 mmol/l to 8.8±0.8 mmol/l, 13.2±1.4 and 7.3±0.4 mmol/l during infusion of noradrenaline, adrenaline or dopamine, respectively. The plasma free fatty acid concentration increased from 0.28±0.10 mmol/l to 0.79±0.21 mmol/l during noradrenaline and to 0.52±0.09 mmol/l during dopamine. In contrast, free fatty acid values averaged baseline values at the end of the adrenaline infusion after an initial increase to 0.72±0.31 mmol/l. Conclusions Administration of noradrenaline, adrenaline or dopamine resulted in persistent increases in $$\dot VO_2 $$ in volunteers. With the exception of the transient adrenaline effect on fatty acids the metabolic actions were steady during 4 h of adrenergic stimulation. Since the adrenergic effect on $$\dot VO_2 $$ is persistent over time a similar action in patients (e.g. septic shock) during treatment with adrenoceptor agonists may be important. Thus, an increase in $$\dot VO_2 $$ during therapy may not only reflect an oxygen debt but also a pharmacodynamic action of adrenoceptor mediated calorigenic and metabolic induction.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-055X
    Schlagwort(e): Schlüsselwörter N-Acetylcystein ; Glutathion ; Lipidperoxidation ; mukoziliäre Klärfunktion ; Beatmung ; Key wordsN-Acetylcysteine ; Glutathione ; Ventilated patient ; Lipid peroxidation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract Oxygen radicals and oxygen radial mediators are thought to be important components in the development of acute lung injury, sepsis, and multiple organ failure. Injured patients, patients with pulmonary diseases, and multiple trauma patients also showed an elevated lipid peroxidation, indicating increased oxidant stress. N-Acetylcysteine (NAC) has been used as an antioxidant in a wide variety of experiments. NAC has been suggested to act by raising concentrations of cysteine, and hence glutathione, and by scavenging of oxidant species [1, 11, 17, 29]. The present study was designed to investigate whether the application of NAC in intubated patients has an effect on concentrations of reduced glutathione in plasma and bronchoalveolar lavage fluid (BAL) and on the lipid peroxidation products malondialdehyde and conjugated dienes. Because NAC has been widely used as a mucolytic drug for the treatment of lung diseases, the influence on tracheobronchial mucus was studied, too. Methods. In a randomized, double-blind, placebo-controlled study, a total of 38 long-term ventilated patients of a surgical intensive care unit were investigated. Patients were treated for 5 days with either 3 g NAC/day or placebo. The plasma concentration of reduced glutathione, malondialdehyde, and conjugated dienes were measured on admission and on the 3rd and 5th days of treatment [8, 34, 48]. Additionally, the numbers of tracheobronchial suctionings were registered and chest radiographs were evaluated. A fibre-bronchoscopy was performed on admission and on the 3rd day of treatment. The amount and viscidity of tracheobronchial secretions were examined semiquantitatively, and glutathione levels were measured in the unconcentrated BAL. The study was approved by the ethics committee of the University of Ulm. Results. The two groups were comparable with respect to age, sex, APACHE II score and diagnosis (Table 1). We found no significant differences in reduced glutathione levels in the plasma or in the BAL (Figs. 1, 2). Plasma concentrations of malondialdehyde were similar (Fig. 3). Only the levels of conjugated dienes were significantly higher on the 5th treatment day in the placebo group (Fig. 4). The organ function of the lung (FiO2, PEEP, PaO2), liver (SGOT, bilirubin), and kidney (creatinine) and coagulation parameters (PTT, prothrombin time, platelet count) were similar in the two groups during the time of investigation. We observed no clinically relevant differences in the tracheobronchial mucus (Table 2). Conclusion. The present data do not support routine use of NAC in ventilated patients, either as an antioxidant or as a mucolytic agent. Intravenous administration of 3 g NAC/day had no clinically relevant effect on glutathione levels, lipid peroxidation products, tracheobronchial mucus, and clinical condition.
    Notizen: Zusammenfassung In einer prospektiven, randomisierten, plazebokontrollierten Doppelblindstudie wurde an insgesamt 38 langzeitbeatmeten Patienten einer operativen Intensivstation überprüft, ob eine routinemäßige intravenöse Applikation von N-Acetylcystein (NAC) sinnvoll ist. Hierzu erhielten 20 Patienten 3 g NAC/Tag kontinuierlich über eine Spritzenpumpe für fünf Tage, 18 Patienten erhielten Plazebo. Bei allen Patienten wurde am 1. Beatmungstag (Ausgangswerte) und am 3. und 5. Behandlungstag die Konzentration von Glutathion, Malondialdehyd und konjugierten Dienen im Plasma bestimmt. An diesen Untersuchungspunkten wurde weiterhin die Zahl der durchgeführten tracheobronchialen Absaugungen registriert und das Röntgenbild des Thorax beurteilt. Alle Patienten wurden am 1. und 3. Beatmungstag bronchoskopiert, wobei die Menge und Zähigkeit des Tracheobronchialsekrets semiquantitativ beurteilt wurde. Zusätzlich wurde eine bronchoalveoläre Lavage (BAL) durchgeführt und die Glutathionkonzentration in der BAL-Flüssigkeit gemessen. Die beiden Gruppen unterschieden sich weder hinsichtlich der Glutathionkonzentration im Plasma noch in der BAL. Auch die Malondialdehydkonzentrationen waren in beiden Gruppen gleich. Die konjugierten Diene waren am 5. Tag in der Plazebogruppe signifikant höher. Hinsichtlich der Funktion von Lunge, Leber, Niere und Gerinnung gab es im zeitlichen Verlauf zwischen den beiden Gruppen keine signifikanten Unterschiede. Klinisch relevante Veränderungen im tracheobronchialen Sekret traten ebenfalls nicht auf. Aufgrund der vorliegenden Ergebnisse ist eine routinemäßige Applikation von N-Acetylcystein bei langzeitbeatmeten Patienten nicht indiziert.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1432-055X
    Schlagwort(e): Schlüsselwörter Mukoziliäre Klärfunktion ; Wärme- und Feuchtigkeitsaustauscher ; Befeuchtung ; Beatmungsfilter ; Filter ; Narkose ; Beatmung ; Key words Mucociliary clearance ; Heat and moisture exchanger ; HME ; Humidity ; Filter ; Semiclosed breathing system ; Artificial instrumentation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Abstract The administration of dry anaesthetic gases for ventilation leads to morphological changes of the tracheobronchial epithelium that may cause postoperative pulmonary complications. Therefore, additional humidification with a heat and moisture exchanger (HME) is suggested for ventilation during anaesthesia, particularly when using semi-open breathing systems. Recommendations concerning the use of a HME in the semi-closed system are controversial. There are no data in the literature as to whether a HME improves mucociliary transport under these conditions. We therefore studied bronchial mucus transport velocity (BTV) with and without the use of a HME in the semi-closed circle system in humans. Patients and methods. The study was approved by the ethics committee of our hospital. In a prospective, randomised trial a total of 22 patients undergoing major abdominal surgery were investigated. In all patients anaesthesia was induced and maintained with midazolam, fentanyl, and vecuronium. After intubation, a HME (BACT/VIRAL HME, Pharma Systems AB, Sweden) was inserted between the endotracheal tube and ventilation tubing in 11 patients; the other 11 were ventilated without a HME and served as controls. Ventilation was assisted with a fresh gas flow of 3 l in a semi-closed system (Dräger Sulla 808 V with an 8 ISO circle system and Ventilog 2 ventilator, Drägerwerk AG, Germany) and a 2:1 mixture of nitrous oxide and oxygen. The fresh gas passed through the soda lime canister. At the end of the operation BTV was measured with a small volume of albumin microspheres labeled with technetium Tc99m, which was deposited on the dorsal surface at the lower ends of the right and left main bronchi via a catheter placed in the inner channel of a fibre-optic bronchoscope [16]. Results. The two groups were comparable with regard to age, sex, preoperative lung function, duration of mechanical ventilation, and dose of anaesthetics (Table 1). There were no statistically significant differences in the BTVs (Fig. 1). Discussion. BTV does not improve with the use of a HME in the semi-closed circle system with a fresh gas flow of 3 l. With modern anaesthesia machines lower fresh gas flows should be administered, whereby the humidity and temperature of the inspired gases are further increased.
    Notizen: Zusammenfassung In einer prospektiven randomisierten Studie wurde der Einfluß eines Wärme- und Feuchtigkeitsaustauschers (HME) auf die bronchiale Schleimtransportgeschwindigkeit während einer Narkosebeatmung im halbgeschlossenen Kreissystem untersucht. Bei 11 Patienten wurde sofort nach erfolgter Intubation ein HME (BACT/VIRAL HME, Pharma Systems AB, Schweden) zwischen Tubus und Beatmungsschläuchen plaziert, bei anderen 11 Patienten wurden die Beatmungsschläuche direkt am Tubus angeschlossen. Nach einer mehrstündigen Narkosebeatmung wurde die bronchiale Schleimtransportgeschwindigkeit (BTG) bestimmt. Zur Bestimmung der BTG wurden zwei MBq Technetium-99 makroaggregiertes Albumin auf die Schleimhautoberfläche der distalen Hauptbronchien mittels Fiberbronchoskopie appliziert und die Wanderungsgeschwindigkeit mit einer Gammakamera erfaßt. Die BTG war in der Filtergruppe sowohl im linken als auch im rechten Hauptbronchus gegenüber der Kontrollgruppe tendenziell höher (Medianwerte links 6,8 versus 5,8 mm/min; rechts 7,5 versus 6,4 mm/min), ein statistisch signikanter Unterschied ließ sich jedoch nicht nachweisen. Die vorliegende Studie zeigt, daß bei einer Narkosebeatmung im halbgeschlossenen System mit einer Frischgaseinleitung vor dem Atemkalk und einem Frischgasfluß von 3 l/min die bronchiale Schleimtransportgeschwindigkeit durch einen HME nicht verbessert wird.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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