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 double-blind randomised comparison of the effects of epidural clonidine, lignocaine and the combination of clonidine and lignocaine in patients with chronic pain.
Twenty patients with chronic pain who previously had obtained analgesia from epidural clonidine and lignocaine agreed to participate in a double-blind crossover study of lumbar epidural clonidine (150 micrograms), lignocaine (40 mg) and the combination of clonidine (150 microgram) and lignocaine (40 mg), all drugs were given in a volume of 3 ml. There were 11 women and 9 men with a mean age 53 years (range: 23-78 years); 9 patients had low back and leg pain, 9 had neuropathic pain, 1 had pelvic pain and 1 Wegner's granulomatosis. Pain intensity and pain relief, as well as sensory and motor blockade, were assessed for 3 h following each injection. ⋯ Overall there was no relationship between neurological blockade and analgesia. The reported side effects appeared to be related to clonidine. These data indicate that in these patients with chronic pain epidural clonidine had a supra-additive effect and behaved more like a co-analgesic than a pure analgesic.
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Comparative Study Clinical Trial
Age is the best predictor of postoperative morphine requirements.
The dose of opioid prescribed for postoperative pain relief has traditionally been based on the weight of the patient. Although a reduction in dose is often suggested for elderly patients over 70 years of age, age-related alterations to dose are generally not considered for younger patients. The records of 1010 patients, under 70 years old, prescribed morphine via patient-controlled analgesia (PCA) after major operations were examined to see what factors might best predict the amount of morphine used in the first 24 h after surgery. ⋯ Although previous studies have noted a correlation between patient age and the amount of opioid needed, this study quantifies this correlation and provides guidelines for opioid dosing. Prescriptions for conventional analgesic regimens should include a dose range centred on values obtained from the above formula to allow for the large interpatient variation in each age group. While initial morphine dose should be guided by patient age and not weight, subsequent doses must still be titrated according to effect.