Pain
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The characteristics and impact of pain were evaluated in a prospective cross-sectional survey of 438 ambulatory AIDS patients recruited from health care facilities in New York City. More than 60% of the patients reported 'frequent or persistent pain' during the 2 wks preceding the study. Patients with pain reported an average of 2.5 different pains. ⋯ Presence of pain and increasing pain intensity were significantly associated with greater impairment in functional ability (Karnofsky Performance Status, BPI functional interference index) and physical symptom distress (Memorial Symptom Assessment Scale). Results demonstrate high levels of pain and pain-related functional impairment among patients with AIDS. The presence and intensity of pain are associated with more advanced HIV disease and pain intensity is also associated with demographic factors (gender, race).
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Comparative Study Clinical Trial
Secondary hyperalgesia to mechanical but not heat stimuli following a capsaicin injection in hairy skin.
A psychophysical investigation was carried out to examine whether heat hyperalgesia exists within the secondary mechanical hyperalgesia zone surrounding a capsaicin injection site on hairy skin. A non-contact laser stimulator was used to deliver temperature controlled stimuli to sites within and outside the zone of mechanical hyperalgesia. Heat testing was carried out before and after the intradermal injection of 50 micrograms of capsaicin into the volar forearm. ⋯ Thus, there was no evidence for heat hyperalgesia within the zone of secondary hyperalgesia to punctate mechanical stimuli. Though the areas of punctate and stroking hyperalgesia were correlated, no correlation existed between the magnitude of capsaicin evoked pain and the areas mechanical hyperalgesia to punctuate and stroking stimuli or the area of flare. This suggests that independent mechanisms may mediate evoked pain, central sensitization that leads to mechanical hyperalgesia, and axon reflexive flare.
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Compounds related to capsaicin and its ultrapotent analog, resiniferatoxin (RTX), collectively referred to as vanilloids, interact at a specific membrane recognition site (vanilloid receptor), expressed almost exclusively by primary sensory neurons involved in nociception and neurogenic inflammation. Desensitization to vanilloids is a promising therapeutic approach to mitigate neuropathic pain and pathological conditions (e.g. vasomotor rhinitis) in which neuropeptides released from primary sensory neurons play a major role. Capsaicin-containing preparations are already commercially available for these purposes. ⋯ We further focus on ligand-induced messenger plasticity, a recently discovered mechanism underlying the analgesic actions of vanilloids. Lastly, we give a brief overview of the current clinical uses of vanilloids and their future therapeutic potential. The possibility is raised that vanilloid receptor subtype-specific drugs may be synthesized, devoid of the undesirable side-effects of capsaicin.
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Comparative Study Clinical Trial
Clinical analgesic equivalence for morphine and hydromorphone with prolonged PCA.
A morphine to hydromorphone equivalence ratio of 7:1 has become the accepted standard, but evidence supporting it comes from single dose studies performed before the advent of patient controlled analgesia (PCA). We compared morphine and hydromorphone use with PCA in bone marrow transplantation patients who required opioids for the control of severe oral mucositis over several days or weeks. An exploratory analysis of clinical records from 102 patients (981 patient days) who used PCA opioids for varying periods of up to 50 days suggested a morphine to hydromorphone use ratio of 3:1. ⋯ Thirty-six patients who used morphine and 21 who used hydromorphone contributed data on pain, satisfaction with pain control, and drug consumption. We observed an average morphine/hydromorphone ratio of 3:1. This differs markedly from historical single dose studies used in published dose equivalency recommendations implying that other equivalency ratios in clinical use may be inappropriate.
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Clinical Trial
Sequential daily relations of sleep, pain intensity, and attention to pain among women with fibromyalgia.
Fifty women with fibromyalgia syndrome (FS) recorded their sleep quality, pain intensity, and attention to pain for 30 days, using palm-top computers programmed as electronic interviewers. They described their previous night's sleep quality within one-half hour of awakening each day, and at randomly selected times in the morning, afternoon, and evening rated their present pain in 14 regions and attention to pain during the last 30 min. We analyzed the 30-day aggregates cross-sectionally at the across-persons level and the pooled data set of 1500 person-days at the within-persons level after adjusting for between-persons variation and autocorrelation. ⋯ A night of poorer sleep was followed by a significantly more painful day, and a more painful day was followed by a night of poorer sleep. Pain attention and sleep were unrelated at the across-persons level of analysis. But there was a significant bi-directional within-person association between pain attention and sleep quality that was not explained by changes in pain intensity.