Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Opioid usage for pain therapy is limited by its undesirable clinical effects, including paradoxical hyperalgesia, also known as opioid-induced hyperalgesia (OIH). However, the mechanisms associated with the development and maintenance of OIH remain unclear. Here, we investigated the effect of serotonin inhibition by the 5-HT3 receptor antagonist, ondansetron (OND), as well as serotonin deprivation via its synthesis inhibitor para-chlorophenylalanine, on mouse OIH models, with particular focus on astrocyte activation. Co-administering of OND and morphine, in combination with serotonin depletion, inhibited mechanical hyperalgesia and astrocyte activation in the spinal dorsal horn of mouse OIH models. Although previous studies have suggested that activation of astrocytes in the spinal dorsal horn is essential for the development and maintenance of OIH, herein, treatment with carbenoxolone (CBX), a gap junction inhibitor that suppresses astrocyte activation, did not ameliorate mechanical hyperalgesia in mouse OIH models. These results indicate that serotonin in the spinal dorsal horn, and activation of the 5-HT3 receptor play essential roles in OIH induced by chronic morphine, while astrocyte activation in the spinal dorsal horn serves as a secondary effect of OIH. Our findings further suggest that serotonergic regulation in the spinal dorsal horn may be a therapeutic target of OIH. PERSPECTIVE: The current study revealed that the descending serotonergic pain-facilitatory system in the spinal dorsal horn is crucial in OIH, and that activation of astrocytes is a secondary phenotype of OIH. Our study offers new therapeutic targets for OIH and may help reduce inappropriate opioid use.

DOI： 10.1016/j.jpain.2020.12.008

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Systemic intravenous administration of opioids is the main treatment strategy for intraoperative and postoperative pain management in patients undergoing cardiac surgery with sternotomy. However, using lower doses of opioids may achieve the well-established benefits of the fast-track approach, with minimal opioid-related side effects. Postoperative pain is coupled with a long stay in the intensive care unit. Although neuraxial anesthesia has some benefits, its use remains controversial due to the potential development of epidural hematoma after anticoagulation for cardiopulmonary bypass and coagulopathy after cardiac surgery. Therefore, there is a need for other effective postoperative analgesic strategies, such as peripheral nerve blocks other than neuraxial anesthesia, for cardiac surgery with sternotomy. The effects of real-time ultrasound-guided transverse thoracic muscle plane (TTP) block on postoperative pain after sternotomy have been reported; however, the pain and discomfort in the epigastric area caused by chest drainage tubes placed through the rectus abdominis muscle also are major postoperative problems after cardiac surgery. Herein, the authors report on a preoperative combination of TTP block and rectus sheath block (RSB) for postoperative pain management after cardiac surgery with sternotomy that addresses pain in both the chest and epigastric areas. Considering previous studies, it is presumed that preemptive analgesic effects can be expected via a combination of the TTP block and RSB, and indeed, the preemptive effect was observed in the present study's patients. In this article, the procedure and tips for combining the TTP block and RSB are introduced.

DOI： 10.1053/j.jvca.2020.07.041

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

OBJECTIVES: The main goal of palliative procedures for congenital heart defects is adequate pulmonary blood flow (PBF), but precise intraoperative PBF evaluation is sometimes difficult. The purpose of this preliminary study was to investigate the usefulness of velocity time integral of the pulmonary vein (PV-VTI) measured by transoesophageal echocardiography (TOE) at the time of palliative procedure as a parameter for PBF. METHODS: Case histories of 63 patients who underwent palliative procedures (bilateral pulmonary artery banding in 18 patients, main pulmonary artery banding in 22 patients and systemic-to-pulmonary artery shunt in 23 patients) and whose intraoperative PV-VTI was measured by TOE from 2011 to 2017 at our centre were retrospectively reviewed. Low-body-weight infants, cases in which cardiopulmonary bypass was used and cases that were anatomically difficult to measure were excluded. RESULTS: PV-VTIs measured at 4 orifices of the pulmonary veins were all significantly decreased in both the bilateral pulmonary artery banding and main pulmonary artery banding groups and increased in the systemic-to-pulmonary artery shunt group immediately after the procedure. There were significant correlations between the velocity time integrals of both right and left pulmonary veins and arterial oxygen saturation (r = 0.564 and 0.703). Nine patients (6 bilateral pulmonary artery banding and 3 systemic-to-pulmonary artery shunt) required unplanned early reoperation due to inadequate PBF; their PV-VTIs were significantly different from those of patients not requiring reoperation. No major complications related to TOE occurred postoperatively. CONCLUSIONS: The PV-VTI measured by TOE during palliative procedures reflected the change of PBF and could help identify patients at higher risk of early reoperation due to inadequate PBF. This parameter may be a useful additional tool for evaluating intraoperative PBF.

DOI： 10.1093/ejcts/ezy465

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Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1186/2193-1801-2-487

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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Language：English   Presentation type：Poster presentation  

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Language：Japanese   Presentation type：Poster presentation  

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