Dexmedetomidine as Part of a Multimodal Analgesic Treatment Regimen for Opioid Induced Hyperalgesia in a Patient with Significant Opioid Tolerance

Suspected opioid-induced hyperalgesia in an infant following surgery: A case report

WHAT IS KNOWN AND OBJECTIVE

Opioids are commonly administered to infants having surgery. Opioid induced hyperalgesia (OIH) is a known adverse effect of opioids in adults but can be difficult to identify in infants.

CASE SUMMARY

A 3-month-old received high-dose fentanyl during anorectoplasty for imperforate anus. He had signs and symptoms of OIH immediately after surgery. His pain and agitation were difficult to manage but improved after he received ketamine.

WHAT IS NEW AND CONCLUSION

OIH should be considered in infants postoperatively when pain worsens despite administration of escalating doses of opioids. Ketamine can be an effective therapeutic for OIH.

Enhanced Understanding of Molecular Interactions and Function Underlying Pain Processes Through Networks of Transcript Isoforms, Genes, and Gene Families

Introduction

Molecular networks based on the abundance of mRNA at the gene level and pathway networks that relate families or groups of paralog genes have supported the understanding of interactions between molecules. However, multiple molecular mechanisms underlying health and behavior, such as pain signal processing, are modulated by the abundances of the transcript isoforms that originate from alternative splicing, in addition to gene abundances. Alternative splice variants of growth factors, ion channels, and G-protein-coupled receptors can code for proteoforms that can have different effects on pain and nociception. Therefore, networks inferred using abundance from more agglomerative molecular units (eg, gene family, or gene) have limitations in capturing interactions at a more granular level (eg, gene, or transcript isoform, respectively) do not account for changes in the abundance at the transcript isoform level.

Objective

The objective of this study was to evaluate the relative benefits of network inference using abundance patterns at various aggregate levels.

Methods

Sparse networks were inferred using Gaussian Markov random fields and a novel aggregation criterion was used to aggregate network edges. The relative advantages of network aggregation were evaluated on two molecular systems that have different dimensions and connectivity, circadian rhythm and Toll-like receptor pathways, using RNA-sequencing data from mice representing two pain level groups, opioid-induced hyperalgesia and control, and two central nervous system regions, the nucleus accumbens and the trigeminal ganglia.

Results

The inferred networks were benchmarked against the Kyoto Encyclopedia of Genes and Genomes reference pathways using multiple criteria. Networks inferred using more granular information performed better than networks inferred using more aggregate information. The advantage of granular inference varied with the pathway and data set used.

Discussion

The differences in inferred network structure between data sets highlight the differences in OIH effect between central nervous system regions. Our findings suggest that inference of networks using alternative splicing variants can offer complementary insights into the relationship between genes and gene paralog groups.

Opioid-Induced Hyperalgesia Is Associated with Dysregulation of Circadian Rhythm and Adaptive Immune Pathways in the Mouse Trigeminal Ganglia and Nucleus Accumbens

The benefits of opioid-based treatments to mitigate chronic pain can be hindered by the side effects of opioid-induced hyperalgesia (OIH) that can lead to higher consumption and risk of addiction. The present study advances the understanding of the molecular mechanisms associated with OIH by comparing mice presenting OIH symptoms in response to chronic morphine exposure (OIH treatment) relative to control mice (CON treatment). Using RNA-Seq profiles, gene networks were inferred in the trigeminal ganglia (TG), a central nervous system region associated with pain signaling, and in the nucleus accumbens (NAc), a region associated with reward dependency. The biological process of nucleic acid processing was over-represented among the 122 genes that exhibited a region-dependent treatment effect. Within the 187 genes that exhibited a region-independent treatment effect, circadian rhythm processes were enriched among the genes over-expressed in OIH relative to CON mice. This enrichment was supported by the differential expression of the period circadian clock 2 and 3 genes (Per2 and Per3). Transcriptional regulators in the PAR bZip family that are influenced by the circadian clock and that modulate neurotransmission associated with pain and drug addiction were also over-expressed in OIH relative to CON mice. Also notable was the under-expression in OIH relative to CON mice of the Toll-like receptor, nuclear factor-kappa beta, and interferon gamma genes and enrichment of the adaptive immune processes. The results from the present study offer insights to advance the effective use of opioids for pain management while minimizing hyperalgesia.

Comparison of Epidural Bupivacaine and Dexmedetomidine with Bupivacaine and Fentanyl for Postoperative Pain Relief in Lower Limb Orthopedic Surgery

Context

Different trials have shown that multimodal analgesia through different techniques is associated with superior pain relief. Opioids as epidural adjunct to local anesthetics have been in use for long and α₂ agonists are being increasingly used for same. The present study aims at comparing the hemodynamic, sedative, and analgesic effects of epidurally administered fentanyl and dexmedetomidine when combined with bupivacaine.

Aims

The aim of this study was to compare the efficacy of epidural dexmedetomidine with bupivacaine versus epidural fentanyl with bupivacaine for postoperative pain relief.

Subjects and Methods

In this ongoing randomized double-blind study, 70 patients with ASA physical status classes I and II of either sex between 20 and 60 years scheduled for lower limb orthopedic surgeries under epidural block were randomly divided into two Groups (n = 35). After epidural block with 15 ml of 0.5% bupivacaine, Group I received 1 μg/kg of fentanyl and Group II received 1 μg/kg of dexmedetomidine. Onset and duration of sensory block, motor block, and time to request for the first postoperative analgesia were recorded.

Statistical Analysis Used

The statistical analysis was performed using SPSS (Statistical Package for the Social Sciences) Version 15.0 Statistical Analysis Software, Mann-Whitney U-test and Chi-square test.

Results

The time to achieve T₁₀ sensory block was early in Group I (dexmedetomidine) (8.10 + 1.03 min) as compared to Group II (15.03 + 1.67 min). Onset of motor was earlier in Group I (15.10 + 1.49 min) as compared to Group II (22.77 + 1.41 min). In Group I (dexmedetomidine), the majority of patients required 2-3 rescue doses, while in Group II (fentanyl), the majority of patients required 3-4 rescue doses.

Conclusions

Dexmedetomidine seems to be a better alternative to fentanyl as an epidural adjuvant due to early onset of sensory anesthesia, prolonged postoperative analgesia, and lower consumption of rescue analgesia.