Anästhesiologischer Fortschritt durch Stereoisomere?

Ohne Zusammenfassung     

Increased brain natriuretic peptide and atrial natriuretic peptide plasma concentrations in dialysis-dependent chronic renal failure and in patients with elevated left ventricular filling pressure

Brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP) plasma concentrations were measured in patients with dialysis-dependent chronic renal failure and in patients with coronary artery disease exhibiting normal or elevated left ventricular end-diastolic pressure (LVEDP) (n = 30 each). Blood samples were obtained from the arterial line of the arteriovenous shunt before, 2 h after the beginning of, and at the end of hemodialysis in patients with chronic renal failure. In patients with coronary artery disease arterial blood samples were collected during cardiac catheterization. BNP and ANP concentrations were determined by radioimmunoassay after Sep Pak C₁₈ extraction. BNP and ANP concentrations decreased significantly (P < 0.001) during hemodialysis (BNP: 192.1 ± 24.9, 178.6 ± 23.0, 167.2 ± 21.8 pg/ml; ANP: 240.2 ± 28.7, 166.7 ± 21.3, 133.0 ± 15.5 pg/ml). The decrease in BNP plasma concentrations, however, was less marked than that in ANP plasma levels (BNP 13.5 ± 1.8%, ANP 40.2 ± 3.5%; P < 0.001). Plasma BNP and ANP concentrations were 10.7 ± 1.0 and 60.3 ± 4. 0 pg/ml in patients with normal LVEDP and 31.7 ± 3.6 and 118.3 ± 9.4 pg/ml in patients with elevated LVEDP. These data demonstrate that BNP and ANP levels are strongly elevated in patients with dialysis-dependent chronic renal failure compared to patients with normal LVEDP (BNP 15.6-fold, ANP 2.2-fold, after hemodialysis; P < 0.001 or elevated LVEDP (BNP 6.1-fold, ANP 2.0-fold, before hemodialysis; P < 0.001), and that the elevation in BNP concentrations was more pronounced than that in ANP plasma concentrations. The present results provide support that other factors than volume overload, for example, decreased renal clearance, are also involved in the elevationin BNP and ANP plasma levels in chronic renal failure. The stronger elevation in BNP concentrations in patients with chronic renal failure and in patients with elevated LVEDP and the less pronounced decrease during hemodialysis suggest a different regulation of BNP and ANP plasma concentrations.[/ p]Abbreviations ANP atrial natriuretic peptide - BNP brain natriuretic peptide - LVEDP left ventricular end-diastolic pressure Correspondence to: C. Haug     

Use of high frequency jet ventilation in extracorporeal shockwave lithotripsy

High frequency jet ventilation (HFJV) was used in 68 patients which were treated with extracorporal shock wave lithotripsy (ESWL) because of stone diseases in the upper urinary tract. The question was whether HFJV in combination with a semiclosed conventional circle system offered a practicable and safe technique to minimize the oscillations which are proportional to the applied tidal volume and to the diaphragmatic movements. With IPPV the mean distance of the stone movement was 32 mm, whereas with the application of HFJV the stones oscillated around their resting position within limits of 2 to 3 mm (ventilation frequency: 200-300/min, driving pressure: 0.6-1.1 bar, tidal volume: 3-8 1/min). The effectiveness of HFJV was monitored by the end-tidal carbon dioxide tension (PeCO2) during intermittently conventional ventilation with "adequate" tidal volumes (TV 15 ml/kg bw). The correlation between PeCO2 and simultaneous measured PaCO2 was r = 0,91. The application of HFJV enhances the efficiency of ESWL. So the treatment of stones of the upper urinary tract can be varied by more subtle dosage of the incoming shock wave energy and by stabilisation of the stones in the underlying ellipsoid of the energy focus.     

Angioplasty using high-frequency energy in coronary stenosis

The most notable limitations of balloon dilatation, acute vascular occlusion with a rate of 3 to 5% and restenosis rate of 20 to 40%, appear at least partially attributable to the mechanism of luminal widening--tearing of the intima and plastic restructuring of plaque material. Alternative angioplasty methods, with the exception of stent implantation, are based on the concept of rendering plaque material, by excision and ablation, with a smoother and less thrombogenic interior surface and to lower the risk of renewed proliferation. Plaque material is removed in three ways: mechanical, by excision; thermically, by laser with relatively low energy density or by high-frequency alternating current; non-thermically, by photoablation with laser of very high energy impulse density. High-frequency alternating current as an energy source for thermic angioplasty is used in four technically different forms of application (Table 1): as indirect or direct high-frequency angioplasty in the scope of the "spark erosion" technique and for heating a balloon during balloon dilatation to achieve thermofusion of the tissue for stabilization of the angioplasty results. With indirect hot-tip high-frequency angioplasty the high-frequency alternating current is employed to rapidly heat an olive-shaped fully isolated metal tip with an integrated resistor, plated with gold to avoid adhesion of thrombotic material. The heat emitted is directed radially. The currently-available system consists of a 20-Watt high-frequency generator with 5 MHz. On application of 10 Watts to tissue in water at 37 degrees C, the temperature achieved at the catheter tip is 130 to 140 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transcranial Doppler sonography as a supplement in the detection of cerebral circulatory arrest

The effects of compromised cerebral hemodynamics on intracranial blood flow velocity patterns (BFV) were studied by noninvasive transcranial Doppler sonography (TCD). Pulsatility index (PI) as an estimation of peripheral cerebral vascular resistance was additionally analyzed. TCD patterns were determined in 19 mechanically ventilated brain dead patients (group A) and 8 resuscitated or severely head injured patients (group B) with intermittent elevated intracranial pressure (ICP). Group A and B TCD data were compared to control measurements obtained in 20 healthy volunteers (group C). Normal TCD recordings (group C) were characterized by anterograde Doppler wave-forms with a predominantly high diastolic flow pattern and PI values of <1. In brain dead patients (group A), flow velocity profiles were significantly decreased. The flow curve consisted of low systolic anterograde spikes, while early diastolic flow components of low amplitudes revealed retrograde phases with a late diastolic zero flow. In some cases, total diastolic circulatory arrest was obtained. PI in brain dead patients was increased by a factor of 10 and was infinite in situations of zero net flow. The low systolic spikes and retrograde diastolic flow may be explained by the effects of reduced intracranial compliance due to increased intracranial pressure (ICP). The detection of bidirectional signals, indicating anterograde and retrograde movements of the blood column or low systolic spikes without diastolic signals, seems to be specific for the condition of brain death. Insonation of the basilar artery should be performed in order to exclude preserved perfusion of infratentorial brain regions during supratentorial circulatory arrest and vice versa. In group B patients, episodes of increased ICP predominantly affected the diastolic flow velocity component. In these patients, resistive Doppler signals with normal or reduced systolic peaks and decreased diastolic flow velocities were expressed as increases in PI. Noninvasive transcranial Doppler sonography appears to confirm cerebral circulatory arrest. Additionally, TCD may be of value for the early detection of impaired cerebral hemodynamics due to changes in intracranial compliance.     

Cerebral blood flow velocity and carbon dioxide vasoreactivity during gamma-hydroxybutyrate/fentanyl anaesthesia in non-neurosurgical patients

In this study the effects of gamma-hydroxybutyrate/fentanyl on cerebral blood flow velocity (CBFV) (as measured in the middle cerebral artery by transcranial Doppler ultrasonography) and on cerebrovascular carbon dioxide reactivity were investigated. Mean CBFV (Vmean) and haemodynamic responses were recorded in 12 non-neurosurgical patients before, during and after induction of general anaesthesia with gamma-hydroxybutyrate (GHB) (20 min constant rate infusion of 100 mg kg-1). Two patients were excluded, one because of bradycardia and the other because of severe myoclonia. During the infusion of GHB, normocapnia was maintained by manually assisting ventilation as necessary. The infusion of GHB did not affect Vmean [awake: 57 +/- 12 cm s-1 (mean +/- SD); 22.5 min: 62 +/- 15 cm s-1, NS difference] or mean arterial blood pressure (MAP) (awake: 97 +/- 12 mmHg; 22.5 min: 89 +/- 10 mmHg, NS). This suggests that cerebral blood flow velocity is unaltered by an anaesthetic dose of GHB. Twenty-five minutes after the start of GHB, fentanyl 3 micrograms kg-1 and vecuronium 0.1 mg kg-1 were given, the trachea was intubated and the lungs were mechanically ventilated to maintain end-tidal PCO2 of 4.6 +/- 0.4 kPa (30 min). At 30 min after the start of the GHB infusion, Vmean and MAP decreased to 38 +/- 10 cm s-1 and 76 +/- 12 mmHg (both P < 0.05 vs 22.5 min) respectively. After adjusting the ventilation to achieve hypocapnia (40 min: end-tidal PCO2 3.5 +/- 0.2 mmHg), Vmean decreased to 29 +/- 7 cm s-1, while MAP did not change. This allowed the relative vasoreactivity (percentage change in Vmean/0.133 kPa change in the end-tidal PCO2 from normocapnia to hypocapnia) to be estimated as 2.7 +/- 1.6% 0.133 kPa-1. This suggests that cerebrovascular response to CO2 during gamma-hydroxybutyrate/fentanyl anaesthesia is maintained.     

S(+)-ketamine up-regulates neuronal regeneration associated proteins following glutamate injury in cultured rat hippocampal neurons

In previous studies, racemic ketamine improved neurological outcome after experimental brain injury and S(+)-ketamine demonstrated neuroprotective effects in neurons after damage in vitro. We compared the expression of regeneration-associated proteins in rat hippocampal neurons after glutamate injury and treatment with S(+)-ketamine versus racemic ketamine. Following an 8 minute exposure to 100 microM glutamate, neurons were maintained untreated or in the presence of S(+)-ketamine or racemic ketamine (10(-4) M, 10(-5) M, 10(-6) M) for one week. Growth-associated protein-43 (GAP-43) and synaptosomal-associated protein-25 (SNAP-25) was analyzed by Western Blotting, the mitochondrial transmembrane potential (MTP) by fluorescence imaging, and [3H]2-deoxy-D-glucose ([3H]2-DG) uptake by scintillation spectrometry. Seven days after exposure, GAP-43 decreased to 15% and SNAP-25 to 30% in the glutamate-injured, untreated neurons. The MTP declined to 50% and [3H]2-DG to 30%. Both S(+)-ketamine and racemic ketamine at 10(-4) M and 10(-5) M minimized the decline in MTP, almost maintaining it at control value. Additionally, S(+)-ketamine and racemic ketamine decreased the reduction in [3H]2-DG. S(+)-ketamine at 10(-4) M and 10(-5) M and racemic ketamine at 10(-4) M reduced the decline in SNAP-25 to 60% of controls (P < .05). However, S(+)-ketamine at 10(-4) M and 10(-5) M only reversed the decrease in GAP-43 to 50% and 40% of controls, respectively (P < .05). We conclude that the synthesis of a growth-associated protein related to plasticity and repair in the adult nervous system is increased by S(+)-ketamine but is not increased by racemic ketamine.     

Cerebral histopathology following portal venous infusion of bacteria in a chronic porcine model

BACKGROUND: The aim of this study was to histologically investigate brain damage after prolonged periods of bacteremia in pigs. METHODS: Twenty-one pathogen-free G?ttingen minipigs were anesthetized and instrumented with a femoral arterial, a pulmonary arterial, and through midline abdominal incision with a portal venous catheter. After craniotomy the superior sagittal sinus was cannulated. A lumbosacral spinal catheter was inserted for sampling of cerebrospinal fluid. Twelve hours after instrumentation, the animals were randomized in two groups: septic and control animals. The septic group received an infusion of 107 colony-forming units per kilogram of living Escherichia coli over 0.5 h through portal venous catheter each day. The control group received saline. Postoperative intensive care treatment included 4 days of controlled mechanical ventilation, sedation, and intravenous nutrition. The brains then were removed, fixed, and processed for histology. Each pathologic alteration found in the samples was assessed and given a severity code (0-3). RESULTS: Sham-operated animals showed no alterations caused by the instrumentation and the intensive care treatment. The septic group showed typical clinical signs of sepsis. Vasopressor support and mechanical ventilation prevented systemic hypotension and hypoxemia. High serum and cerebrospinal fluid levels of interleukin-6 and tumor necrosis factor-alpha were detected. The septic group showed severe histologic abnormalities of the brain including perivascular edema, spongiform degeneration, hyperemia, and purpura. Damage of neurons was seen including eosinophilic cytoplasm, shrunken nuclei, and disintegration of the nuclear membrane. CONCLUSIONS: Abdominal sepsis induced severe brain damage that was not related to systemic hypoxia or ischemia. High cerebrospinal fluid levels of tumor necrosis factor-alpha and interleukin-6 were related to an inflammatory process in the brain resulting in cerebral edema and death of neurons.     

Beitrag zur Klinik der Hypocalcinosen

Zusammenfassung Es wird über einen Fall von Hypocalcinose der Haut bei einer 22jährigen Erstschwangeren berichtet. Klinisch handelte es sich um eine Ps. p., ohne daß bei der Kranken vor, neben oder nach der pustulösen Dermatose (über 1 Jahr nachbeobachtet) eine Psoriasis vulgaris nachzuweisen war. Eine Strumektomie war nicht in der Anamnese, eine Ursache des Absinkens des Bcs. war, von der Gravidität und einer substernalen, mäßige Druckerscheinungen verursachenden Struma abgesehen, nicht mit Sicherheit zu eruieren. Die Erscheinungen hatten in leichterer Form schon 2 Jahre vor der Gravidität bestanden, wobei ähnlich wie bei anderen Störungen des Calciumstoffwechsels (Tetanie, Spasmophilie) jeweils das Frühjahr die bevorzugte Jahreszeit für die rezidivierenden Eruptionen war. Ein sehr schwerer Ausbruch der Krankheit im 3. Schwangerschaftsmonat konnte mit AT 10 geheilt werden. Eine korrekte Einstellung des Bcs. konnte infolge der Indolenz der Kranken nicht durchgeführt werden, so daß es, zum Teil beinormalen Blutcalciumwerten, zu mehreren Rezidiven kam, wobei späterhin auch recht uncharakteristische Hauterscheinungen zur Beobachtung kamen. Wie die schwere Eruption zu Beginn der Schwangerschaft, so heilten auch die im weiteren Verlauf beobachteten Schübe auf AT 10 prompt ab. Im ganzen wurden 90 ccm AT 10, daneben keine Calciumpräparate verabreicht. Die Gravidität konnte ohne Gefahr ausgetragen werden. Die bisher gültige Ansicht, daß die während der Schwangerschaft auftretenden Hauthypocalcinosen (I. h. bzw. Ps. p.) eine Indikation zur Schwangerschaftsunterbrechung darstellen, ist daher zu revidieren bzw. in jedem Fall ein Versuch mit AT 10 abzuwarten.Mit 5 Textabbildungen.