Articles: cations.
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Curr Opin Anaesthesiol · Apr 1998
Fluid replacement for hypotensive injury victims: how, when and what risks?
Intravenous fluid administration is considered universally indicated for patients with post-traumatic hypotension of presumed hemorrhagic origin, regardless of the mechanism of injury, anatomic location, and whether hemostasis has been achieved. This premise is based primarily on animal studies in which blood loss results from a controlled catheter withdrawal. However, more recent hemorrhage models that incorporate a vascular injury, as well as recently completed clinical trials, have indicated that attempts to restore blood pressure before surgical hemostasis may have the undesirable effects of accentuating hemorrhage and mortality.
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Peripheral nerve injury may lead to neuropathic pain that has been considered unresponsive to opioids. In animal models of neuropathic pain, there are previous data of both increased and decreased effect of opioids, but only limited information of the long-term effects of opioid treatment on the development of the symptoms of neuropathy. The possibility of preventing the development of signs of neuropathy with either a single pre-injury injection or chronic postinjury administration of morphine was studied in rats with unilateral peripheral neuropathy due to tight ligation of the L5 and L6 spinal nerves. ⋯ No autotomy, signs of distress, altered social behaviour or morphine withdrawal was seen in any of the rats. The fact that neuropathic pain-like symptoms were not attenuated by any of the treatments studied could indicate that neither premedication nor postoperative pain management with systemic morphine is effective in preventing postoperative neuropathic pain. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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Chronic pain patients have complex problems. Due to this, much research effort has been expended on the classification of pain patients and the classification of pain problems. A mainstay of most pain classification systems is the use of the physical location of the pain. ⋯ Further, large demographic differences between patients with different painful sites, even when they have at least one pain site in common, suggests that grouping patients based on a single site descriptor may be inappropriate. These findings have important implications for chronic pain description and classification. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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Temporal summation of pain is suggested to be an important factor during various clinical conditions. Controversies exist as to whether temporal summation exists for Adeltafibre-mediated first pain. The aim of the present human experimental study was to investigate the importance of stimulus configuration (intensity, inter-pulse interval, location) for temporal summation of radiant (laser)- and contact-heat-induced pain. ⋯ Taking the latency from stimulation to perception into consideration, we were able to differentiate and find summation of first (Adeltafibre-mediated) and second pain (C fibre-mediated). Summation of first pain was more pronounced for high (38 degrees C) than for low (30-32 degrees C) baseline temperature. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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Positron emission tomography (PET) and accumulation of H(2)(15)O as a marker of neuronal activity were used to create maps of cerebral blood-flow changes evoked by painful heat stimulation in 10 subjects. Two levels of painful tonic and phasic heat stimuli were applied with use of a newly developed contact heat thermode on the volar surface of the dominant (right) arm. The subjects participated in two separate PET sessions. ⋯ Finally, the location of the activation site in the cingulate cortex was different from that observed during tonic heat pain. This study has provided more evidence for the existence of a common pain-processing network engaged during the perception of different levels of toxic and phasic heat pain. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.