Der Anaesthesist
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The efferent sympathetic nervous system is organized into subsystems that innervate and regulate via separate peripheral sympathic pathways the different autonomic target organs. This review discusses mechanisms through which this efferent system may be causally involved in the generation of pain. Clinical pain syndromes in which this may be the case are "complex regional pain syndromes" (CRPS) type I (previously reflex sympathetic dystrophy) and type II (recently causalgia). ⋯ From this follows that the pathophysiologal processes operating in CRPS may occur at four levels of integration that interact with each other: effector organ, peripheral afferent and sympathetic neurone, spinal cord, supraspinal centres. Recent experimental investigations on rats show that the sympathetic nervous system is possibly also causally involved in the generation of inflammation and inflammatory pain. The mechanisms by which this occurs are different from those operating in SMP during CRPS.
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General cardiovascular properties of ketamine: "In vitro", ketamine has moderate negative inotropic effects. "In vivo", a significant central sympathomimetic action with consecutive hemodynamic effects is dominant. The sympathomimetic potency of ketamine is one of the most significant pharmacological features of the substance with direct clinical implications. Monoanaesthesia with S-(+)-ketamine: After application of racemic ketamine or S(+)-ketamine as well, identic and significant increases in plasma catecholamines, arterial pressure and heart rate are observed. This outstanding sympathomimetic action is beneficial in induction of patients with shock or asthmatic state. TIVA and analgosedation with S-(+)-ketamine and midazolam: The sympathomimetic effect of S(+)-ketamine, and racemic ketamine as well, is mitigated by midazolam. Nevertheless, significant increases in heart rate and arteriel pressure might be observed. Clinical use of the combination is common in short procedures like reposition maneuvers. Of greater importance is the use for analgosedation in patients with cardiovascular instability, particularly in patients with exogenous catecholamine demand. TIVA and analgosedation with S-(+)-ketamine and propofol: When S(+)-ketamine is combined with propofol, the sympatholytic effects of propofol are counteracted by S(+)-ketamine, and stable hemodynamic conditions are presented. This combination seems useful for TIVA in patients with hypotonic dysregulation or endocrine deficits like hypothyreosis and adrenal insufficiency. Furthermore, analgosedation with S(+)-ketamine and propofol is advantageous, when rapid recovery is necessary and negative circulatory effects should be avoided. ⋯ Sympathoadrenergic and hemodynamic effects of S(+)-ketamine and racemic ketamine are generally identical. The distinctest action is observed, when S(+)-ketamine is used as a monoanaesthetic. In combination with midazolam, a significant reduction is achieved. In combination with propofol, the sympatholytic effects of this hypnotic agent are compensated by S(+)-ketamine. With respect to sympathoadrenergic and hemodynamic reactions, the clinical position of S(+)-ketamine is unchanged. Nevertheless, a significant clinical progress can be expected due to improved recovery and reduced substance load, when racemic ketamine is replaced by S(+)-ketamine.
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The pharmacological profile of ketamine: Until recently, clinically available ketamine was a racemic mixture containing equal amounts of two enantiomers, (S)- and (R)-ketamine. The pharmacological profile of racemic ketamine is characterized by the so called dissociative anesthetic state and profound sympathomimetic properties. Among the different sites of action, N-methyl-D-aspartate (NMDA)-receptor antagonism is considered to be the most important neuropharmacological mechanism of ketamine. ⋯ In combination with midazolam and propofol, excellent control of analgosedation was found, making both combinations suitable for situations in which repeated neurological assessment of patients is necessary. In emergency and disaster medicine, (S)-ketamine is of outstanding importance because of its minimal logistic requirements, the chance for intramuscular administration and the broad range of use for analgesia, anaesthesia and analgosedation as well. Further perspectives of (S)-ketamine may be the treatment of chronic pain and the assumed neuroprotective action of the substance.
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Due to the recent development in operative medicine medical and organizational demands on perioperative patient care have changed significantly. Corresponding to the responsibility of the operative colleagues for therapy of the primary disease, anesthesiologists have to account for monitoring and treatment of vital functions throughout the perioperative period, starting from preoperative evaluation until postoperative care. The postanesthesia recovery unit has a key role in perioperative management. ⋯ The terminology should be changed in the future in order to better characterize the new task spectrum, e.g. in perioperative anaesthetic care unit (PACU) for medical and medicolegal reasons patient security must have absolute priority above economic aspects. Effective postoperative pain control using epidural or patient-controlled intravenous analgesia may increase patient comfort and reduce postoperative complications caused by sympathoadrenergic activation. Both method can be safely used on normal wards provided that close cooperation and training of ward personnel is guaranteed as well as continuous supervision by a specialized acute pain service.
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The shift of age distribution within the population of industrialized societies has led to an increased need of treating diseases in elderly patients and at the same time bearing an increased operative risk. Today, the development of surgical techniques and intensive care treatment enables us to carry out numerous procedures in geriatric patients. Innovative surgical techniques like minimal invasive surgery with minor trauma due to the surgical approach changed patient's categories, also. ⋯ Contrasting experiences made in most other countries and especially in the third world, in Germany economic restrictions have not been encountered as of yet. Economical conditions, an increase in surgical procedures in elderly patients and advances in medical science will continue to change the surgical patient's characteristics profoundly. From the physicians viewpoint we have actively participate in this development by personal interaction with the patient, by interdisciplinary cooperation and prompt social and political action.