Pain
-
Randomized Controlled Trial Clinical Trial
Effects of intravenous ketamine, alfentanil, or placebo on pain, pinprick hyperalgesia, and allodynia produced by intradermal capsaicin in human subjects.
The importance of N-methyl-D-aspartate (NMDA) receptor-mediated sensitization of central nervous system (CNS) neurons is well established in animal models of acute and chronic pain. A human model of central sensitization would be useful in screening new NMDA antagonists and establishing dose regimens for clinical trials in patients with pain related to sensitization of CNS neurons. We used this model to examine the effects of intravenous infusions of two centrally acting analgesics, the NMDA receptor antagonist ketamine and the morphine-like opioid agonist alfentanil. ⋯ Because the drugs were given systemically and produced side effects in all subjects, we cannot specify the site or sites of action nor conclusively rule out a non-specific 'active placebo' response as the cause for reduction of symptoms. Arguing against an 'active placebo' response, however, was the lack of analgesic effect of intravenous midazolam (mean dose; 3.4 mg, titrated to produce side effects of similar magnitude to ketamine and alfentanil) given at 145 min after capsaicin in 9 subjects who had received saline from 25 to 60 min. The results of this study suggest that neural systems sensitive to NMDA receptor antagonists and opioids participate in capsaicin-evoked pain phenomena, and support the feasibility of pharmacological studies using the intradermal capsaicin model.
-
Randomized Controlled Trial Clinical Trial
Relaxation and imagery and cognitive-behavioral training reduce pain during cancer treatment: a controlled clinical trial.
Few controlled clinical trials of psychological interventions for cancer pain relief exist in spite of frequent support for their importance as adjuncts to medical treatment. This study compared oral mucositis pain levels in 4 groups of cancer patients receiving bone marrow transplants (BMT): (1) treatment as usual control, (2) therapist support, (3) relaxation and imagery training, and (4) training in a package of cognitive-behavioral coping skills which included relaxation and imagery. A total of 94 patients completed the study which involved two training sessions prior to treatment and twice a week 'booster' sessions during the first 5 weeks of treatment. ⋯ Average visual analogue scale (VAS) report of pain within the therapist support group was not significantly lower than the control group (P = 0.103) nor significantly higher than the training groups. Patient reports of relative helpfulness of the interventions for managing pain and nausea matched the results of VAS reports. From these results, we conclude that relaxation and imagery training reduces cancer treatment-related pain; adding cognitive-behavioral skills to the relaxation with imagery does not, on average, further improve pain relief.