Der Anaesthesist
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Pre-emptive analgesia is based on the idea that analgesia initiated before a nociceptive event will be more effective than analgesia commenced afterwards, and that its effects will outlast the pharmacological duration of action of the analgesic used. The idea of pre-emptive analgesia is based upon experimental neurophysiological work demonstrating that afferent nociceptive impulses result in alterations of central nervous system function. These changes, most easily elicited by C-fibre afferents, particularly affect the spinal dorsal horn. ⋯ Clinical studies have so far only used short-term analgesia. To permit extrapolation from the experimental to the clinical situation, pre-emption in the surgical context must correspond adequately to the duration and extent of the nociception involved. Studies of pre-emptive analgesia in a clinically relevant form, i.e. where nociception and analgesia are correctly matched, are called for.
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AIMS AND PATHOPHYSIOLOGY: Intensive care patients are exposed to a number of noxious stimuli. They require individual analgesia and sedation to reduce and moderate the stress response to endogenous and exogenous stressors. In patients with SIRS (systemic inflammatory response syndrome), pathophysiological conditions with multiple organ dysfunction or failure demand special efforts and a specific regimen of analgosedation. The main goals are the absence of cardiocirculatory depression or, if at all possible, cardiocirculatory stabilization, absence of negative pulmonary, renal, hepatic and immunological side effects, preservation of a moderate stress response, and vertical and horizontal control appropriate to the clinical situation.
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Cerebral blood flow autoregulation, CO2 reactivity and the pressure-volume relationship may be impaired or abolished in patients with intracranial mass lesions, brain trauma, cerebral vasospasm or increased cerebral elastance. Sedatives, analgetics, and anesthetics may induce major changes in cerebral blood flow, cerebral metabolism and intracranial pressure (ICP). The inadequate use of these drugs may aggravate the preexisting intracranial pathology and may worsen outcome. ⋯ Ketamine may increase ICP specifically in subjects with spontaneous ventilation. With mechanical hyperventilation and constant systemic hemodynamics, ketamine fails to increase ICP in most of the patients. Alpha-2-adrenergic agonists produce no significant changes in ICP, although there may be a transient decrease in ICP with lower doses.
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Randomized Controlled Trial Comparative Study Clinical Trial
[Total intravenous anesthesia (TIVA) in geriatric surgery. S-(+)-ketamine versus alfentanil].
In this prospective, randomized study, two regimens of total intravenous anaesthesia (TIVA), with propofol and S(+)-ketamine (S-ketamine) and with propofol and alfentanil, were compared with reference to endocrine stress response, circulatory effects and recovery. METHODS. The investigation was conducted in two groups of 20 ASA I-III patients over 60 years of age who were scheduled for endoprothetic orthopaedic surgery. ⋯ On the other hand, TIVA with propofol and alfentanil showed sympatholytic properties, with negative circulatory effects and a remarkable reduction of endocrine stress response. This might be beneficial in patients with hypertension and states of endocrine hyperfunction. Both regimens were accompanied by such typical side effects as dreams, delayed recovery, reduced ventilation, and emesis, which should also be considered.