Pain
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Randomized Controlled Trial Clinical Trial
Classical conditioning and the placebo effect.
Stimulus substitution models posit that placebo responses are due to pairings of conditional and unconditional stimuli. Expectancy theory maintains that conditioning trials produce placebo response expectancies, rather than placebo responses, and that the expectancies elicit the responses. ⋯ Verbal information reversed the effect of conditioning trials on both placebo expectancies and placebo responses, and the magnitude of the placebo effect increased significantly over 10 extinction trials. These data disconfirm a stimulus substitution explanation and provide strong support for an expectancy interpretation of the conditioned placebo enhancement produced by these methods.
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Randomized Controlled Trial Clinical Trial
The visual analogue pain intensity scale: what is moderate pain in millimetres?
One way to ensure adequate sensitivity for analgesic trials is to test the intervention on patients who have established pain of moderate to severe intensity. The usual criterion is at least moderate pain on a categorical pain intensity scale. When visual analogue scales (VAS) are the only pain measure in trials we need to know what point on a VAS represents moderate pain, so that these trials can be included in meta-analysis when baseline pain of at least moderate intensity is an inclusion criterion. ⋯ For those reporting severe pain 85% scored over 54 mm with a mean score of 75 mm. There was no difference between the corresponding VAS scores of men and women. Our results indicate that if a patient records a baseline VAS score in excess of 30 mm they would probably have recorded at least moderate pain on a 4-point categorical scale.
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Randomized Controlled Trial Clinical Trial
Ketamine, an NMDA receptor antagonist, suppresses spatial and temporal properties of burn-induced secondary hyperalgesia in man: a double-blind, cross-over comparison with morphine and placebo.
Effects of morphine and ketamine (NMDA receptor antagonist) on temporally summated pain ('wind-up-like pain') and spatial aspects of secondary hyperalgesia were investigated in 12 healthy volunteers. Hyperalgesia was produced by a local 1 degree burn injury covering 12.5 cm2 on the medial surface of the calf. Primary hyperalgesia was determined by measuring heat pain detection threshold (HPDT) within the site of injury. ⋯ Morphine did not significantly change the size of the area of secondary hyperalgesia and did not affect 'wind-up-like pain'. Ketamine or morphine did not change thermal detection thresholds. We conclude that spatial and temporal mechanisms, underlying secondary hyperalgesia, are mediated by glutamatergic transmission via NMDA receptors.
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Randomized Controlled Trial Clinical Trial
Effectiveness of oral sucrose and simulated rocking on pain response in preterm neonates.
Feeding and carrying have been interventions used by caregivers throughout history in relieving distress in infants. Recent studies on the food substance sucrose have elucidated the comforting effect of the taste component of feeding while studies of rocking have examined the comforting effect of the vestibular component of carrying. The purpose of this study was to determine the effectiveness of sucrose and simulated rocking alone and in combination on diminishing pain response in preterm neonates undergoing routine heelstick procedure in the neonatal intensive care unit (NICU). ⋯ Although the simulated rocking did promote quiet sleep, which has been reported in earlier studies to blunt pain response, there was no difference between simulated rocking and control groups in either facial expressions indicative of pain or heart rate. The implication of these results is that sucrose, but not simulated rocking may be a means of diminishing pain from minor procedures in preterm infants. Further research is needed on the use of sucrose for more than one procedure as well as examining the contact component of natural rocking, as opposed to simulated rocking.
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Despite its importance in clinical practice, little research has examined memory for pain in children. This prospective study tried to justify the use of children's pain recall in clinical practice. The purpose of this study was to (a) investigate the accuracy of children's recall of their worst and average pain intensity when controlling for the effects of repeated pain measurement and (b) examine the influence of children's anxiety, age, general memory ability and pain coping strategies on this accuracy. ⋯ The accuracy of children's recalled pain intensities was high and showed little decrement over 1 week. Older children had more accurate recall of their worst pain intensity. Anxiety, general memory ability and pain coping strategies were not related to accuracy of recalled pain intensities.