The journal of pain : official journal of the American Pain Society
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Randomized Controlled Trial Comparative Study
Placebo-controlled comparison of a morphine/dextromethorphan combination with morphine on experimental pain and hyperalgesia in healthy volunteers.
In this double-blind, placebo-controlled, crossover study we compared the analgesic effect of a single oral dose of 30-mg dextromethorphan and 30-mg morphine combination (MS/DM) to 30 mg morphine (MS) alone and either placebo or 30 mg dextromethorphan (DM) on cutaneous sensitization induced by heat/capsaicin (topical) sensitization on the forearm and the brief thermal sensitization model on the thigh in 22 healthy volunteers. Outcome measures were areas of secondary hyperalgesia to brush and von Frey hair stimulation in both sensitization models and the painfulness of acute thermal noxious stimulation on the upper arm. Compared with placebo, both MS/DM and morphine had some effect on the secondary hyperalgesia and reduced the painfulness of a noxious thermal stimulus. The analgesic effect of MS/DM was not superior to that of morphine on any outcome measure. These results differ from preclinical studies with animal experimental pain models in which DM markedly potentiated the analgesic effects of opioids, but they are in accordance with recent clinical trials for chronic pain. ⋯ Adding dextromethorphan to morphine (1:1 ratio) did not enhance analgesia on measures of experimental cutaneous sensitization and acute noxious thermal stimulation in healthy volunteers. The results differ from preclinical studies but agree with clinical trials. Human experimental models of pain and neuronal sensitization, which are responsive to oral opioids, allow efficient study of opioid combination analgesics and simplify the process for determining the optimal dose and/or dose ratio.
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The purpose of this study was to document analgesic use for limb and clavicle injuries in the pediatric emergency department (ED) and to determine whether a physician-oriented pain scale form on the patient's chart would enhance the administration of analgesia. Patients 3 to 18 years old were recruited prospectively in our tertiary pediatric ED in Toronto. The study included 4 crossover periods, 2 with the pain scale form on the patient's chart and 2 without. A total of 310 patients were recruited, mean age was 10 years, 64% were boys, and 62% had sustained fractures. The mean pain score was 4.4. Only 90 (29%) patients received an analgesic in the ED, and 65 (72%) of them were ordered by a physician. Only 24 (20%) in the study group and 22 (14%) in the control group received sufficient analgesia (P = .13). The median time to physician-initiated analgesia after arrival was 2.0 hours (1.0 to 3.3 hours), without a significant difference between groups. Pain control was 4-fold more appropriate in children receiving opioids versus nonopioids. Physician pain reminders did not enhance, and other measures should be taken to increase the dispensing of analgesia. ⋯ This is the first study to evaluate whether the addition of a physician-oriented pain-scale form on the chart of patients with injuries improves administration of analgesia in the ED. We found that physicians do not give sufficient analgesia even with this reminder form.
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Comparative Study
Sex and pain-related psychological variables are associated with thermal pain sensitivity for patients with chronic low back pain.
Biologic and psychological associations with evoked pain sensitivity have been extensively studied in healthy subjects but not among subjects with clinical pain syndromes. This study involved patients with chronic low back pain and investigated whether: 1) sex differences existed for thermal pain sensitivity; and 2) sex, fear-avoidance beliefs, and/or pain catastrophizing influenced thermal pain sensitivity. Thirty-three consecutive patients enrolled in a pain rehabilitation program completed self-report questionnaires and underwent quantitative sensory testing with an established protocol for thermal stimuli. Women had elevated pain sensitivity for measures of tolerance and temporal summation but not for first pulse response. In the multivariate models predicting thermal pain sensitivity, sex was associated with tolerance, and fear-avoidance beliefs were associated with first pulse response. Sex and pain catastrophizing were associated with temporal summation of thermal pain. Future studies involving clinical samples are necessary to replicate these findings and to explore the involvement of cortical structures. ⋯ This study suggests that sex, fear-avoidance beliefs, and pain catastrophizing were associated with thermal pain sensitivity for patients with chronic low back pain. These results corroborated sex differences in tolerance and temporal summation observed in the experimental pain literature for healthy subjects. These results also suggest the potential for these specific pain-related beliefs to be associated with a sensitized state because previous studies have demonstrated their association to clinical pain reports, and this study demonstrated associations with thermal pain sensitivity.
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The purpose of this study was to identify and describe subgroup profiles based on self-reported pain intensity, disability, self-efficacy, fear of movement/(re)injury, and catastrophizing in patients with musculoskeletal pain. Two primary health care samples (n = 215 and n = 161) were used. Self-report questionnaires were completed at the start of physical therapy treatment. Cluster analysis was used to generate subgroups. Three subgroups were identified in sample 1 and replicated in sample 2. These were labeled "High self-efficacy-Low fear-avoidance," "Low self-efficacy-Low fear-avoidance," and "Low self-efficacy-High fear-avoidance." The subgroups differed significantly in work-status in both samples (P < .001), but not in age, gender, or duration of pain. The results show the presence of subgroups based on pain intensity, disability, self-efficacy, fear of movement/(re)injury, and catastrophizing. The profile patterns suggest that different management strategies may be relevant in each subgroup. ⋯ This article presents subgroups of patients with musculoskeletal pain with different profiles in pain intensity, disability, and psychosocial variables possible to modify by physical therapy management. The results could potentially aid clinicians in tailoring assessment and treatment approaches to each subgroup.
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The purpose of this investigation was to clarify mixed findings reported in selective attention investigations. To accomplish this, recently published dot-probe data from 36 patients with chronic musculoskeletal pain and 29 healthy control participants were reanalyzed with consideration of fear of pain (FOP) as a categorical variable. FOP groups were identified by using a variety of strategies and represented differing conceptualizations of the FOP construct. Selective attention for sensory pain, affect pain, and health catastrophe words was assessed by using raw dot-probe detection latencies and the bias, congruency, and incongruency indices. Analysis of the raw detection latencies revealed no significant interactions that permit inferences regarding attentional shifts to or away from specific word types. Analyses of the attention indices revealed no evidence of pain-related selective attention as a function of FOP or the interaction between clinical status and FOP, regardless of the FOP categorization method used; however, for FOP groups derived by using the cluster method, participants with high FOP--all patients--exhibited hypervigilance for all word types on the dot-probe task when compared with those with low FOP. Implications for various categorical conceptualizations of FOP and future research directions are discussed. ⋯ Fear of pain can be used to categorize people into groups more or less vulnerable to disabling effects of pain. When fear of pain groups are derived by using measures of general and pain-specific fearfulness, people with high fear of pain are likely to selectively attend all potentially threatening stimuli in their environment.