Pain
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Clinical Trial
Sensory-motor interactions of human experimental unilateral jaw muscle pain: a quantitative analysis.
Experimental muscle pain was elicited by bolus injection of 0.15 ml of 5% hypertonic saline into the human masseter muscle. The sensory experience was described using 10-cm visual analogue scales (VAS) and the McGill Pain Questionnaires (MPQ) on 10 subjects. Effects of pain on deliberately unilateral mastication were quantitatively assessed in 13 other male subjects using kinematic recordings of the mandible and jaw muscle electromyography (EMG). ⋯ Moreover, agonist EMG activity during pain was significantly lower in the ipsilateral masseter muscle (20.3 +/- 25.4%, P < 0.05) as compared to pre-pain root-mean-square (RMS) values. The observed sensory-motor interactions can be explained by a facilitatory effect of activity in nociceptive muscle afferents on inhibitory brain-stem interneurons during agonist action. Thus, generated movements have smaller amplitudes and they are slower which most likely represents a functional adaptation to experimental jaw muscle pain.
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Clinical Trial
The effects of isoflurane on repeated nociceptive stimuli (central temporal summation).
Central temporal summation of afferent nociceptive stimuli is involved in central hyperexcitability. This is assumed to be an important mechanism in the nociceptive system which is probably activated during surgery and trauma. The purpose of the present study was to investigate if isoflurane has a specific effect on central temporal summation in humans. ⋯ In contrast, 2-4-fold higher isoflurane concentrations (1.00-1.50 vol% end-tidal) that normally produce surgical anaesthesia were required to depress the nociceptive reflex to repetitive stimuli. This indicates that central temporal summation in the nociceptive system is a potent mechanism, and that isoflurane has a weak potency for depressing temporal summation in humans. As such isoflurane alone is not adequate for inhibiting surgically evoked hyperexcitability.
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Randomized Controlled Trial Comparative Study Clinical Trial
A comparison of morphine, pethidine and fentanyl in the postsurgical patient-controlled analgesia environment.
This study was designed to evaluate whether there is any scientific basis for clinicians' preferences for selecting opioids for use in patient-controlled analgesia (PCA) and to determine whether there are any patients' preferences for being treated with any of these opioids. Results were obtained for 55 postoperative patients recruited to investigate putatively equivalent doses of 3 commonly used opioids--morphine, pethidine and fentanyl--when self-administered postoperatively. No significant differences in the incidence of side effects between groups were found with the exception of more pruritus reported in the group given morphine. ⋯ The majority of patients reported being very satisfied with their postoperative pain management and with PCA, with no differences in satisfaction between the 3 opioid-treated groups. A senior consultant anaesthetist, when asked to make a judgement, was not able to identify which agent each patient was receiving with a better than chance accuracy. These findings suggest that while there may be subtle differences in patient response to these 3 commonly used opioids, none was obviously superior when used for postoperative PCA.
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Randomized Controlled Trial Clinical Trial
Determinants of success and failure of EMLA.
Although EMLA is known to be an effective topical anesthetic, its rate of success is unknown. Indeed, researchers have suggested that EMLA may fail with young and apprehensive children. Therefore, the objectives of this study were to assess EMLA's rate of success as well as factors which predict success. ⋯ Those who had a poor outcome were more anxious than those with a good outcome. Age of child was not a factor. Strategies for improving efficient use of EMLA were recommended.
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Comparative Study Clinical Trial Controlled Clinical Trial
A comparison of the effects of noxious and innocuous counterstimuli on experimentally induced itch and pain.
We have studied experimentally induced itch (using histamine iontophoresis) and pain (using topical mustard oil) in healthy human volunteers, measured using visual analogue scale (VAS) ratings. The effects of the following counterstimuli were evaluated: innocuous vibration; innocuous transcutaneous electrical nerve stimulation (TENS); innocuous warming of skin; noxious heating of skin; noxious chemical skin stimulation (using mustard oil); mildly noxious constant current transdermal electrical stimulation. Innocuous stimuli applied 2 min after histamine or mustard oil challenge produced a modest reduction of itch and pain ratings (20-30%), which did not persist for more than 20 sec when the counterstimuli were removed. ⋯ The differential effects of noxious counterstimuli on itch and pain do not support the suggestion that itch is a subliminal form of pain. Noxious counterstimuli are likely to act via a central rather than peripheral mechanism. The novel finding that a persistent anti-pruritic state can be induced by transdermal constant current may be useful in conditions of clinical itch.