Der Anaesthesist
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In 1977 a new anaesthesiology preoperative evaluation clinic was started for evaluation of all elective surgical patients for their fitness to undergo anaesthesia. Physical examination, medical history and anaesthetic risk assessment are assessed in a standardized manner with the aid of computer menus. Comprehensive laboratory tests included electrocardiography, lung function assessment (vital capacity and forced exspiratory volume within 1 s), chest X-ray, and arterial blood gas analysis and blood chemistry analysis with an SMA-22 (System Multi Analyzer). ⋯ We found that perioperative complications and adverse outcome correlated with preoperative data and physical examination. The main source of perioperative morbidity and mortality was the cardiovascular system, followed by nephrologic diseases, correlating exactly with preoperative BUN and plasma creatinine. These studies also underlined the value of the ASA physical status to predict perioperative outcome.(ABSTRACT TRUNCATED AT 250 WORDS)
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Despite a widespread approach to explain the molecular mechanisms of anaesthetic agents, the complex state of "general anaesthesia" is still not completely understood. Voltage-activated sodium channels from human brain cortex served as a model membrane protein to investigate anaesthetic drug-protein interactions using a novel electrophysiological voltage-clamp technique. Sodium channels are already well-characterized important integral membrane proteins responsible for the generation of the fast-propagated action potential and thus are vital components for neuronal signal integration and cell communication. In order to elucidate the molecular interactions of intravenous anaesthetics with single human brain sodium channels, representative compounds of four different clinical intravenous anaesthetic groups were used to correlate different types of clinical anaesthesia with differential anaesthetic effects on the molecular level. METHODS. Single sodium channels from human brain cortex were incorporated into artificial phospholipid bilayers and studied under our standard experimental conditions (Electrolyte solution: 500 mM NaCl, 10 mM HEPES, pH 7.4, Temp. 22-25 degrees C) with an electrophysiological voltage-clamp technique. In the presence of a channel activator (1 microM batrachotoxin) single-channel characteristics (fractional open time, single-channel conductance and amplitude, steady-state activation behaviour) were characterized for control conditions and in the presence of various doses of four different anaesthetic agents (pentobarbital, propofol, ketamine, midazolam). RESULTS. During control measurements the investigated human brain sodium channels showed stable and reproducible characteristics on the range expected for batrachotoxin-modified sodium channels in bilayers. After completion of the control measurement the effects of the four different general anaesthetics pentobarbital, propofol, ketamine and midazolam were investigated on the same control sodium channels. All four substances demonstrated a blocking effect of sodium channel conductance (pentobarbital: K50: concentration for 50% block of the maximal conductance block: 0.69 mM; blockmax: maximal conductance block (%): 100%; propofol: K50: 0.02 mM, blockmax: 28%; ketamine: K50: 1.1 mM, blockmax: 71%; midazolam: K50: 0.52 mM, blockmax: 100%). Furthermore, a destabilization of the steady-state activation process could be demonstrated. These effects were dose dependent, but only pentobarbital and propofol demonstrated these effects at or near clinically relevant serum concentrations. ⋯ At the clinical level, "general anaesthesia" is a highly complex phenomenon. Similarly, anaesthetics may demonstrate a multimechanistic mode of action also at the molecular level. In this study all four investigated anaesthetic compounds interacted with at least two primary sodium channel functions, leading to a voltage-independent reduction of the fractional channel open time and an interaction with the steady-state activation behaviour, respectively. The effects of pentobarbital and propofol were detectable at concentrations within the range of serum concentrations achieved during clinical anaesthesia, whereas ketamine and midazolam demonstrated qualitatively similar effects exceeding this range 10- to 50-fold. Thus, the human brain sodium channel might serve as a molecular target only for pentobarbital and propofol. This suggests that different types of clinical anaesthesia may correlate with differential actions of anaesthetics on the molecular level.
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Randomized Controlled Trial Clinical Trial
[The effect of thoracic epidural anesthesia on the pathophysiology of the eventration syndrome].
Abdominal mesenteric traction (MT) results in decreased mean arterial pressure (MAP), systemic vascular resistance (SVR) and increased cardiac output (CO). This response is induced by a considerable release of prostacyclin (PGI2). Precipitous falls in systemic arterial pressure related to central and/or autonomic nervous reflex arcs also have been described during operations on the upper abdominal viscera. ⋯ Our data clearly indicate that the mesenteric traction response consists in relevant haemodynamic alterations and a significant decrease of paO2. Stable haemodynamics and paO2 following cyclooxygenase inhibition signify an action mediated by prostacyclin. Deafferentation of the splanchnic nerves by supplementary thoracic epidural anaesthesia did not influence either prostacyclin release or the decrease in blood pressure and paO2 after traction on the mesentery root...
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The interaction of immunocompetent cells with the vascular endothelium is of prime importance for the development of septic multiple organ failure. There is evidence from in-vitro studies that the methylxanthine derivative pentoxifylline can attenuate the extent of inflammatory reactions by amplification of cell-derived endogenous regulators. ⋯ Consequently, pentoxifylline improves perfusion in the microcirculation as well as tissue oxygenation. Further studies will clarify whether the promising results obtained with pentoxifylline in experimental septic shock will be confirmed under clinical conditions.
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Various new muscle relaxants are available: atracurium, rocuronium and vecuronium all have an intermediate duration of action, whereas doxacurium and pipecuronium are long-acting and mivacurium is a short-acting nondepolarizing muscle relaxant. The duration of action of atracurium and mivacurium is determined by their degradation, which makes them unique among the nondepolarizing muscle relaxants in this respect. ⋯ Because recovery from them is slow, long-acting agents should preferentially be used only when postoperative mechanical ventilation is intended. The use of a peripheral nerve stimulator is the only reliable guide to appropriate administration of muscle relaxants.