Regional anesthesia and pain medicine
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Reg Anesth Pain Med · May 2008
Comparative StudyThe effect of opioid dose and treatment duration on the perception of a painful standardized clinical stimulus.
The concept of opioid-induced hyperalgesia has recently gained prominence as a contributing factor for opioid tolerance and long-term treatment failure. But whereas the preclinical data for this phenomenon are strong, the mixed clinical data derive primarily from experimental pain models conducted in volunteers and heroin addicts, and nonstandardized clinical stimuli, e.g., surgery. The primary objective of this study is to delineate the effect of opioid dose and treatment duration on pain intensity and unpleasantness ratings following a standardized clinical pain stimulus. ⋯ The results of this study bolster preclinical and experimental pain models demonstrating enhanced pain perception in subjects receiving opioid therapy. This simple clinical model may provide a useful tool in examining opioid-induced hyperalgesia.
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Shivering, which usually occurs as a thermoregulatory response to cold, may also occur following general or neuraxial anesthesia. Some of the causative factors of this type of shivering may be common to both, but some are particular to neuraxial anesthesia. ⋯ Both pharmacological and nonpharmacological mechanisms have been found to be effective in reducing this shivering. This review aims to elucidate the mechanisms of the shivering that occurs during neuraxial anesthesia, and to examine strategies for prevention and treatment of this shivering.
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Reg Anesth Pain Med · May 2008
Intensity of the stimulating current may not be a reliable indicator of intraneural needle placement.
The current intensity at which a motor response is elicited with an intraneural needle placement has been inadequately studied. We hypothesized that electrical current delivered through an intraneurally placed needle does not always result in an evoked motor response. Our secondary objective was to determine the relationship between electrical current intensity and needle-to-nerve distance. ⋯ Specific response to nerve stimulation with currents <0.2 mA occurred only when the needle tip was positioned intraneurally. However, motor response could be absent with intraneural needle placement at a current intensity of up to 1.7 mA.
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Reg Anesth Pain Med · May 2008
Contralateral neuropathic pain following a surgical model of unilateral nerve injury in rats.
Damage to peripheral nerves provokes chronic neuropathic pain that lasts beyond the duration of the nerve injury. The presence of pain signs have been reported in areas other than those attributed to the injured nerve, i.e., in contralateral regions. We evaluated the presence, magnitude, and chronology of mechanical and cold allodynia in the contralateral paw of rats undergoing unilateral ligation of the L5 and L6 spinal nerves. ⋯ After L5 and L6 spinal nerve ligation, rats developed mechanical and cold allodynia in the contralateral paw, suggesting extraterritorial development of neuropathic signs. This finding has implications for future study design and therapeutic approaches.