Loss of spectral alpha power during spine surgery: what could be wrong?

The electroencephalographic signatures of anesthetic drugs relate to a specific set of action mechanisms within the neural circuits. During intraoperative care, the recognition and correct interpretation of the EEG spectrogram can be used as a tool to guide anesthetic administration. For example, loss of alpha power during propofol anesthesia may be a sign of lighter level of hypnosis and/or of an increase in nociceptive inputs. We describe a case report of inadvertent interruption of propofol delivery that was first detected by changes in the electroencephalogram spectrogram.

Multimodal General Anesthesia: Theory and Practice.

Balanced general anesthesia, the most common management strategy used in anesthesia care, entails the administration of different drugs together to create the anesthetic state. Anesthesiologists developed this approach to avoid sole reliance on ether for general anesthesia maintenance. Balanced general anesthesia uses less of each drug than if the drug were administered alone, thereby increasing the likelihood of its desired effects and reducing the likelihood of its side effects. To manage nociception intraoperatively and pain postoperatively, the current practice of balanced general anesthesia relies almost exclusively on opioids. While opioids are the most effective antinociceptive agents, they have undesirable side effects. Moreover, overreliance on opioids has contributed to the opioid epidemic in the United States. Spurred by concern of opioid overuse, balanced general anesthesia strategies are now using more agents to create the anesthetic state. Under these approaches, called "multimodal general anesthesia," the additional drugs may include agents with specific central nervous system targets such as dexmedetomidine and ones with less specific targets, such as magnesium. It is postulated that use of more agents at smaller doses further maximizes desired effects while minimizing side effects. Although this approach appears to maximize the benefit-to-side effect ratio, no rational strategy has been provided for choosing the drug combinations. Nociception induced by surgery is the primary reason for placing a patient in a state of general anesthesia. Hence, any rational strategy should focus on nociception control intraoperatively and pain control postoperatively. In this Special Article, we review the anatomy and physiology of the nociceptive and arousal circuits, and the mechanisms through which commonly used anesthetics and anesthetic adjuncts act in these systems. We propose a rational strategy for multimodal general anesthesia predicated on choosing a combination of agents that act at different targets in the nociceptive system to control nociception intraoperatively and pain postoperatively. Because these agents also decrease arousal, the doses of hypnotics and/or inhaled ethers needed to control unconsciousness are reduced. Effective use of this strategy requires simultaneous monitoring of antinociception and level of unconsciousness. We illustrate the application of this strategy by summarizing anesthetic management for 4 representative surgeries.

[Lidocaine in oncological surgery: the role of blocking in voltage-gated sodium channels. A narrative review]. / Lidocaína em cirurgia oncológica: o papel do bloqueio dos canais de sódio dependentes de voltagem. Revisão narrativa.

BACKGROUND: The current evidence suggests that oncological surgery, which is a therapy used in the treatment of solid tumors, increases the risk of metastasis. In this regard, a wide range of tumor cells express Voltage-Gated Sodium Channels (VGSC), whose biological roles are not related to the generation of action potentials. In epithelial tumor cells, VGSC are part of cellular structures named invadopodia, involved in cell proliferation, migration, and metastasis. Recent studies showed that lidocaine could decrease cancer recurrence through its direct effects on tumor cells and immunomodulatory properties on the stress response. OBJECTIVE: The aim of this narrative review is to highlight the role of VGSC in tumor cells, and to describe the potential antiproliferative effect of lidocaine during the pathogenesis of metastasis. CONTENTS: A critical review of literature from April 2017 to April 2019 was performed. Articles found on PubMed (2000-2019) were considered. A free text and MeSH-lidocaine; voltage-gated sodium channels; tumor cells; invadopodia; surgical stress; cell proliferation; metastasis; cancer recurrence-for articles in English, Spanish and Portuguese language-was used. A total of 62 were selected. CONCLUSION: In animal studies, lidocaine acts by blocking VGSC and other receptors, decreasing migration, invasion, and metastasis. These studies need to be replicated in humans in the context of oncological surgery.

Lidocaine in oncological surgery: the role of blocking in voltage-gated sodium channels. A narrative review / Lidocaína em cirurgia oncológica: o papel do bloqueio dos canais de sódio dependentes de voltagem. Revisão narrativa

Abstract Background: The current evidence suggests that oncological surgery, which is a therapy used in the treatment of solid tumors, increases the risk of metastasis. In this regard, a wide range of tumor cells express Voltage-Gated Sodium Channels (VGSC), whose biological roles are not related to the generation of action potentials. In epithelial tumor cells, VGSC are part of cellular structures named invadopodia, involved in cell proliferation, migration, and metastasis. Recent studies showed that lidocaine could decrease cancer recurrence through its direct effects on tumor cells and immunomodulatory properties on the stress response. Objective: The aim of this narrative review is to highlight the role of VGSC in tumor cells, and to describe the potential antiproliferative effect of lidocaine during the pathogenesis of metastasis. Contents: A critical review of literature from April 2017 to April 2019 was performed. Articles found on PubMed (2000-2019) were considered. A free text and MeSH-lidocaine; voltage-gated sodium channels; tumor cells; invadopodia; surgical stress; cell proliferation; metastasis; cancer recurrence - for articles in English, Spanish and Portuguese language - was used. A total of 62 were selected. Conclusion: In animal studies, lidocaine acts by blocking VGSC and other receptors, decreasing migration, invasion, and metastasis. These studies need to be replicated in humans in the context of oncological surgery.

Resumo Justificativa: As evidências atuais sugerem que a cirurgia oncológica, usada no tratamento de tumores sólidos, aumenta o risco de metástase. Nesse sentido, uma ampla gama de células tumorais expressa Canais de Sódio Dependentes de Voltagem (CSDV), cujos papéis biológicos não estão relacionados à produção de potencial de ação. Nas células epiteliais tumorais, o CSDV é parte integrante de estruturas celulares denominadas invadópodes, que participam da proliferação, migração e metástase celular. Estudos recentes mostraram que a lidocaína pode diminuir a recorrência do câncer através de efeitos diretos nas células tumorais e de propriedades imunomoduladoras na resposta ao estresse. Objetivo: O objetivo desta revisão narrativa é analisar o papel do CSDV nas células tumorais e descrever o possível efeito antiproliferativo da lidocaína na patogênese das metástases. Conteúdo: Foi realizada uma revisão crítica da literatura de Abril de 2017 a Abril de 2019. Os artigos encontrados no PubMed (2000 − 2019) foram analisados. Pesquisamos textos de linguagem livre e descritores MeSH-lidocaína; canais de sódio dependentes de voltagem; células tumorais; invadópodes; estresse cirúrgico; proliferação celular; metástase; recorrência do câncer − em artigos publicados em inglês, espanhol e português. Foram selecionadas 62 publicações. Conclusão: Em estudos empregando animais, a lidocaína atua bloqueando o CSDV e outros receptores, diminuindo a migração, invasão e metástase. Esses estudos precisam ser replicados em humanos submetidos a cirurgia oncológica.