Pain
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There has been an explosion of interest in the utility of cannabinoids as potential analgesics. This systematic review critically synthesizes the evidence for cannabinoid analgesic effects on quantitative sensory testing outcomes in both healthy adults and patients with chronic noncancer pain. Our systematic review protocol is preregistered on PROSPERO (CRD42018117367). ⋯ Patterns of findings from studies with healthy subjects did not substantively differ from those with chronic noncancer pain. However, these observations are qualified by the high degree of inconsistency across studies and methodological heterogeneity. We offer recommendations for future studies to improve study rigor and reproducibility.
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What’s the relevance?
Remifentanil’s ultrashort-acting kinetics have driven its growth as a reliable technique for maintaining intraoperative analgesia. It is now one of the most widely used synthetic opioids in anesthesia.
However these unique pharmacological characteristics are associated with both Opioid Induced Hyperalgesia and Acute Opioid Tolerance, and possibly increase the risk of chronic pain after surgery.
Details:
Niedermayer and team performed a large, multicenter, propensity-matched observational study of remifentanil use during intra-abdominal surgery, and its association with postoperative pain in the PACU. Importantly the patients receiving epidural analgesia in addition to TIVA GA were also included. Volatile GA was excluded.
Among 16,420 patients meeting inclusion criteria, 3,652 GA/TIVA patients received remifentanil and were matched to 3,318 controls, and 829 GA/epi received remifentanil, being matched to 631 controls. Mean remifentanil infusions rates were 0.11 and 0.13 mcg/kg/min for non-EA and EA groups respectively.
They showed:
Among GA-only patients, remifentanil was associated with higher PACU pain scores (both on arrival and discharge), greater analgesic requirements and more PONV – however there was no decrease of either time-to-extubation or PACU discharge.
Interestingly, the epidural analgesia cohort also showed higher PACU pain scores when receiving remifentanil.
The rapid nociceptive changes due to remifentil are well known, however real clincial consequences remain unclear. This large observational study highlights the detrimental analgesic effects of remifentanil in the most immediate post-op period, reminding anesthetists and anesthesiologists that gold-standard intraoperative analgesia may come at a cost.
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Explore collected articles answering: Is remifentanil associated with Opioid Induced Hyperalgesia and Acute Opioid Tolerance?
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Observational Study
Vitamin D insufficiency increases risk of chronic pain among African Americans experiencing motor vehicle collision.
African Americans experience an increased burden of motor vehicle collision (MVC), post-MVC musculoskeletal pain, and vitamin D insufficiency. In this prospective multicenter study, we tested the hypothesis that African Americans (n = 133) presenting to the emergency department after MVC with low peritraumatic vitamin D levels would have worse chronic musculoskeletal pain outcomes compared to individuals with sufficient vitamin D. Vitamin D levels were assessed in the early aftermath of MVC through enzyme-linked immunosorbent assay, and pain severity was assessed using the 0 to 10 numeric rating scale at 6 weeks, 6 months, and 1 year. ⋯ Secondary analyses suggest that the effect of vitamin D on post-MVC pain outcomes may be influenced by genetic variation in IL-10 and NLRP3. Further studies are needed to assess the impact of vitamin D insufficiency on pain outcomes in African Americans experiencing MVC and other common trauma exposures, to assess factors affecting this relationship, and to assess the efficacy of administering vitamin D in the immediate aftermath of MVC to prevent chronic pain. Such low-cost, nonopioid interventions are urgently needed to address chronic pain development after MVC.
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Native Americans (NAs) have a higher prevalence of chronic pain than other U. S. racial/ethnic groups, but there have been few attempts to understand the mechanisms of this pain disparity. This study used a comprehensive battery of laboratory tasks to assess peripheral fiber function (cool/warm detection thresholds), pain sensitivity (eg, thresholds/tolerances), central sensitization (eg, temporal summation), and pain inhibition (conditioned pain modulation) in healthy, pain-free adults (N = 155 NAs, N = 150 non-Hispanic Whites [NHWs]). ⋯ There were no group differences on any measure, except that NAs had lower cold-pressor pain thresholds and tolerances, indicating greater pain sensitivity than NHWs. These findings suggest that there are no group differences between healthy NAs and NHWs on peripheral fiber function, central sensitization, or central pain inhibition, but NAs may have greater sensitivity to cold pain. Future studies are needed to examine potential within-group factors that might contribute to NA pain risk.