jueves, 11 de enero de 2018

Neurotoxicidad y anestesia / Anesthesia neurotoxicity

Enero 11, 2018. No. 2960
Neurotoxicidad anestésica en pacientes pediátricos
Anesthetic Neurotoxicity in Pediatric Patients
Ayse B. Ozer and Sibel Ozcan
Current Topics in Anesthesiology
book edited by Riza Hakan Erbay, ISBN 978-953-51-2918-9, Print ISBN 978-953-51-2917-2, Published: February 8, 2017 under CC BY 3.0 license. © The Author(s).
Abstract In recent years, an increasing number of publications have shown the negative effects of anesthetics on the developing brain and have made inquiries about anesthesia for pediatric patients in practice. Anesthesia is applied to millions of children for surgery, imaging, and other invasive procedures; the issue is very serious and concerns. In this chapter, experimental and clinical studies about the issue have been summarized. As a result, anesthetic drugs except alpha-2 adrenergic agonist anesthetic (NMDA antagonist or a GABA agonist) used in pediatric patients (especially if there is no painful situation) have potential neurotoxicity. Particularly, if anesthesia exposure was applied in the fragile period (the first 4 years) and if used at higher concentrations or repeated anesthesia application, adverse effects of anesthesia exposure on the developing brain have been claimed. But, the issue is not fully clarified yet. Keywords: anesthesia, neurotoxicity, neonatal, developing brain
Un mecanismo celular reversible por presión de anestésicos generales capaz de alterar un posible mecanismo para la conciencia
A pressure-reversible cellular mechanism of general anesthetics capable of altering a possible mechanism for consciousness
Kunjumon I. Vadakkan
Springerplus. 2015; 4: 485. Published online 2015 Sep 7. doi: 10.1186/s40064-015-1283-1
ASbstract
Different anesthetics are known to modulate different types of membrane-bound receptors. Their common mechanism of action is expected to alter the mechanism for consciousness. Consciousness is hypothesized as the integral of all the units of internal sensations induced by reactivation of inter-postsynaptic membrane functional LINKs during mechanisms that lead to oscillating potentials. The thermodynamics of the spontaneous lateral curvature of lipid membranes induced by lipophilic anesthetics can lead to the formation of non-specific inter-postsynaptic membrane functional LINKs by different mechanisms. These include direct membrane contact by excluding the inter-membrane hydrophilic region and readily reversible partial membrane hemifusion. The constant reorganization of the lipid membranes at the lateral edges of the postsynaptic terminals (dendritic spines) resulting from AMPA receptor-subunit vesicle exocytosis and endocytosis can favor the effect of anesthetic molecules on lipid membranes at this location. Induction of a large number of non-specific LINKs can alter the conformation of the integral of the units of internal sensations that maintain consciousness. Anesthetic requirement is reduced in the presence of dopamine that causes enlargement of dendritic spines. Externally applied pressure can transduce from the middle ear through the perilymph, cerebrospinal fluid, and the recently discovered glymphatic pathway to the extracellular matrix space, and finally to the paravenular space. The pressure gradient reduce solubility and displace anesthetic molecules from the membranes into the paravenular space, explaining the pressure reversal of anesthesia. Changes in membrane composition and the conversion of membrane hemifusion to fusion due to defects in the checkpoint mechanisms can lead to cytoplasmic content mixing between neurons and cause neurodegenerative changes. The common mechanism of anesthetics presented here can operate along with the known specific actions of different anesthetics.
Keywords: Consciousness, General anesthetics, Pressure reversal, Semblance hypothesis, Inter-membrane contact, Membrane hemifusion, Partial hemifusion, Complete hemifusion, Membrane fusion, Neurodegeneration
Una espada de doble filo: efectos anestésicos volátiles en el cerebro neonatal
A Double-Edged Sword: Volatile Anesthetic Effects on the Neonatal Brain
Sunny Chiao, Zhiyi Zuo
Brain Sci. 2014 Jun; 4(2): 273-294. Published online 2014 Apr 16. doi: 10.3390/brainsci4020273
Abstract
The use of volatile anesthetics, a group of general anesthetics, is an exceedingly common practice. These anesthetics may have neuroprotective effects. Over the last decade, anesthetic induced neurotoxicity in pediatric populations has gained a certain notoriety based on pre-clinical cell and animal studies demonstrating that general anesthetics may induce neurotoxicity, including neuroapoptosis, neurodegeneration, and long-term neurocognitive and behavioral deficits. With hundreds of millions of people having surgery under general anesthesia worldwide, and roughly six million children annually in the U.S. alone, the importance of clearly defining toxic or protective effects of general anesthetics cannot be overstated. Yet, with our expanding body of knowledge, we have come to learn that perhaps not all volatile anesthetics have the same pharmacological profiles; certain ones may have a more favorable neurotoxic profile and may actually exhibit neuroprotection in specific populations and situations. Thus far, very few clinical studies exist, and have not yet been convincing enough to alter our practice. This review will provide an update on current data regarding volatile anesthetic induced neurotoxicity and neuroprotection in neonatal and infant populations. In addition, this paper will discuss ongoing studies and the trajectory of further research over the coming years.
Keywords: anesthesia, anesthetics, neuroprotection, neurotoxicity, pediatrics, volatile anesthetics, preconditioning, postconditioning, ischemic conditioning

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