Documento de consenso para la monitorización neurofisiológica intraoperatoria multimodal en procedimientos neuroquirúrgicos. Fundamentos básicos / Consensus document for multimodal intraoperatory neurophisiological monitoring in neurosurgical procedures. Basic fundamentals

El presente trabajo pretende establecer una guía de actuación consensuada entre anestesiólogos y neurofisiólogos para realizar una monitorización neurofisiológica intraoperatoria efectiva en procedimientos tanto neuroquirúrgicos, como en aquellos en los que existe un riesgo de lesión neurológica funcional. En la primera parte, se describen las principales técnicas utilizadas en la actualidad para la monitorización neurofisiológica intraoperatoria. En segundo lugar, se describen los factores anestésicos y no anestésicos que pueden afectar al registro eléctrico de las estructuras del sistema nervioso. Posteriormente, se analizan los efectos adversos de las técnicas más comunes derivados de su utilización. Y, por último, se describen las diferentes pautas a seguir tras la aparición de los diferentes eventos clínicos intraoperatorios.(AU)

The present work aims to establish a guide to action, agreed by anaesthesiologists and neurophysiologists alike, to perform effective intraoperative neurophysiological monitoring for procedures presenting a risk of functional neurological injury, and neurosurgical procedures. The first section discusses the main techniques currently used for intraoperative neurophysiological monitoring. The second exposes the anaesthetic and non-anaesthetic factors that are likely to affect the electrical records of the nervous system structures. This section is followed by an analysis detailing the adverse effects associated with the most common techniques and their use. Finally, the last section describes a series of guidelines to be followed upon the various intraoperative clinical events.(AU)

Consensus document for multimodal intraoperatory neurophisiological monitoring in neurosurgical procedures. Basic fundamentals. / Documento de consenso para la monitorización neurofisiológica intraoperatoria multimodal en procedimientos neuroquirúrgicos. Fundamentos básicos.

The present work aims to establish a guide to action, agreed by anaesthesiologists and neurophysiologists alike, to perform effective intraoperative neurophysiological monitoring for procedures presenting a risk of functional neurological injury, and neurosurgical procedures. The first section discusses the main techniques currently used for intraoperative neurophysiological monitoring. The second exposes the anaesthetic and non-anaesthetic factors that are likely to affect the electrical records of the nervous system structures. This section is followed by an analysis detailing the adverse effects associated with the most common techniques and their use. Finally, the last section describes a series of guidelines to be followed upon the various intraoperative clinical events.

Manejo de la presión arterial en pacientes neuroquirúrgicos y neurocríticos / Management of blood pressure in neurosurgical and neurocritical patients

Las diferencias etiológicas y fisiopatológicas entre las entidades que pueden requerir una intervención neuroquirúrgica o el establecimiento de cuidados neurocríticos hace imposible hablar del control de la presión arterial en el paciente neurocrítico o neuroquirúrgico de un modo genérico. Con este razonamiento en mente, decidimos revisar por separado el control de la presión arterial en algunas de las entidades patológicas a las que más frecuentemente nos enfrentamos en la práctica clínica. Los temas revisados son: traumatismo craneoencefálico, ictus isquémico agudo, cirugía de los aneurismas intracraneales, cirugía de las malformaciones arteriovenosas cerebrales, cirugía tumoral encefálica, cirugía medular y cuidados de la lesión medular aguda

The etiological and pathophysiological differences between diseases that may require a neurosurgical intervention or the establishment of neurocritical care make it impossible to talk about the control of blood pressure in the neurocritical or neurosurgical patient in a generic manner. With this reasoning in mind, we decided to review separately the control of blood pressure in some of the pathologies we most frequently faced in clinical practice. The topics reviewed are: cranial brain trauma, acute ischemic stroke, intracranial aneurysm surgery, cerebral arteriovenous malformation surgery, brain tumor surgery, spinal cord surgery and acute spinal cord injury

Dexmedetomidina en el manejo de la vía aérea difícil con fibrobroncoscopio en paciente despierto afecto de síndrome de Klippel-Feil / Dexmedetomidine in difficult airway management with a fibre-optic bronchoscope in the awake patient with Klippel-Feil Syndrome

El síndrome de Klippel-Feil es una enfermedad que se caracteriza por la fusión congénita de vértebras cervicales, que condiciona una limitación e inestabilidad cervical. En estos casos la mejor opción es la intubación orotraqueal con fibrobroncoscopio con el paciente despierto. La ventaja es que se minimizan los movimientos cervicales que podrían conllevar un daño neurológico. En estos pacientes una sedación adecuada, junto con la instilación de anestésico local en la faringe y la hipofaringe es clave para reducir las molestias del paciente y conseguir la intubación orotraqueal con éxito. La dexmedetomidina es un agonista selectivo de los receptores α-2 adrenérgicos que produce sedación y ansiolisis al nivel del locus coeruleus, sin provocar depresión respiratoria, y preservando la colaboración del paciente. Presentamos el caso de un paciente con síndrome de Klipple-Feil y vía aérea difícil en el que utilizamos una perfusión de dexmedetomidina a dosis de 0,6μg/kg/h como sedación para la intubación orotraqueal con fibrobroncoscopio con el paciente despierto

Klippel-Feil Syndrome is a disease characterised by congenital fusion of cervical vertebra, which leads to cervical limitation and instability. In these cases, the best option is the orotracheal intubation with the fibre-optic bronchoscope with the patient awake. The advantage is that cervical movements that could lead to neurological damage are minimised. In these patients, adequate sedation, together with instillation of local anaesthetic in the pharynx and hypopharynx, is the key to reducing patient discomfort and achieving successful orotracheal intubation. Dexmedetomidine is a selective α2- adrenergic receptor agonist that produces sedation and analgesia at the locus coeruleus without producing respiratory depression, as well as maintaining patient collaboration. The case is presented of a patient with Klippel-Feil Syndrome and difficult airway management, who was given a dexmedetomidine infusion at 0.6μg/kg/h as sedation for an awake fibre-optic endotracheal intubation

Dexmedetomidine in difficult airway management with a fibre-optic bronchoscope in the awake patient with Klippel-Feil Syndrome. / Dexmedetomidina en el manejo de la vía aérea difícil con fibrobroncoscopio en paciente despierto afecto de síndrome de Klippel-Feil.

Klippel-Feil Syndrome is a disease characterised by congenital fusion of cervical vertebra, which leads to cervical limitation and instability. In these cases, the best option is the orotracheal intubation with the fibre-optic bronchoscope with the patient awake. The advantage is that cervical movements that could lead to neurological damage are minimised. In these patients, adequate sedation, together with instillation of local anaesthetic in the pharynx and hypopharynx, is the key to reducing patient discomfort and achieving successful orotracheal intubation. Dexmedetomidine is a selective α2- adrenergic receptor agonist that produces sedation and analgesia at the locus coeruleus without producing respiratory depression, as well as maintaining patient collaboration. The case is presented of a patient with Klippel-Feil Syndrome and difficult airway management, who was given a dexmedetomidine infusion at 0.6µg/kg/h as sedation for an awake fibre-optic endotracheal intubation.

Density spectral array of BIS VISTA™ monitoring system in a functional hemispherectomy. / Monitorización con espectrograma del sistema de monitorización BIS VISTA™ en una hemisferectomía funcional.

We present the case of an adult patient with drug-resistant epilepsy caused by extensive inflammation in the right cerebral hemisphere. She was scheduled to undergo right functional hemispherectomy, which is common in pediatric surgery, but about which few studies have been published with respect to adult patients. During the intraoperative period, the density spectral array of the bilateral bispectral index (BIS) VISTATM monitoring system was used. We observed a power increase in low frequency (0.1-4Hz) and alpha bands (8-12Hz) in the right hemisphere, where the epileptogenic focus was. During disconnection from the frontal lobe, there was a marked decrease of power in low frequency and alpha bands on the right side, with no changes during disconnection from other areas of the brain. We think that further studies are needed to determine whether the density spectral array can be a useful tool for monitoring the effectiveness of functional hemispherectomy.

Anaesthesia management in epilepsy surgery with intraoperative electrocorticography. / Manejo anestésico en la cirugía de epilepsia con electrocorticografía intraoperatoria.

Epilepsy surgery is a well-established treatment for patients with drug-resistant epilepsy. The success of surgery depends on precise presurgical localisation of the epileptogenic zone. There are different techniques to determine its location and extension. Despite the improvements in non-invasive diagnostic tests, in patients for whom these tests are inconclusive, invasive techniques such intraoperative electrocorticography will be needed. Intraoperative electrocorticography is used to guide surgical resection of the epileptogenic lesion and to verify that the resection has been completed. However, it can be affected by some of the anaesthetic drugs used by the anaesthesiologist. Our objective with this case is to review which drugs can be used in epilepsy surgery with intraoperative electrocorticography.

Influencia de la anestesia general sobre el tronco encefálico / Influence of general anaesthesia on the brainstem

El papel que desempeña el tronco encefálico en el control del funcionamiento basal del organismo y los detalles sobre cómo la anestesia general puede influir sobre este aún no está completamente definido. Sin embargo, en cada anestesia general el anestesiólogo debe ser consciente de la interacción de los fármacos anestésicos y la función del tronco encefálico en relación con la homeostasis del organismo. Como resultado de esta interacción habrá cambios en el nivel de consciencia, los reflejos protectores del organismo, el ritmo respiratorio, la frecuencia cardíaca, la temperatura o la presión arterial entre otros. La función del tronco encefálico puede ser explorada usando 3 enfoques diferentes: a través de la exploración clínica, analizando los cambios en la actividad eléctrica del cerebro o mediante el uso de técnicas de neuroimagen. El presente artículo de formación continuada trata de la influencia de los efectos de los fármacos anestésicos sobre la función del tronco encefálico. Para ello se estudia la exploración clínica de los nervios craneales y de diversos arcos reflejos afectados, el análisis de las señales eléctricas, tales como los cambios electroencefalográficos, y lo que se sabe acerca del tronco encefálico a través del uso de técnicas de imagen, más concretamente a través de imágenes obtenidas por resonancia magnética funcional. El objetivo es proporcionar al anestesiólogo clínico una visión global de la interacción entre los cambios inducidos por los anestésicos relacionados con la función del tronco encefálico (AU)

The exact role of the brainstem in the control of body functions is not yet well known and the same applies to the influence of general anaesthesia on brainstem functions. Nevertheless in all general anaesthesia the anaesthesiologist should be aware of the interaction of anaesthetic drugs and brainstem function in relation to whole body homeostasis. As a result of this interaction there will be changes in consciousness, protective reflexes, breathing pattern, heart rate, temperature or arterial blood pressure to name a few. Brainstem function can be explored using three different approaches: clinically, analyzing changes in brain electric activity or using neuroimaging techniques. With the aim of providing the clinician anaesthesiologist with a global view of the interaction between the anaesthetic state and homeostatic changes related to brainstem function, the present review article addresses the influence of anaesthetic drug effects on brainstem function through clinical exploration of cranial nerves and reflexes, analysis of electric signals such as electroencephalographic changes and what it is known about brainstem through the use of imaging techniques, more specifically functional magnetic resonance imaging (AU)

Influence of general anaesthesia on the brainstem. / Influencia de la anestesia general sobre el tronco encefálico.

The exact role of the brainstem in the control of body functions is not yet well known and the same applies to the influence of general anaesthesia on brainstem functions. Nevertheless in all general anaesthesia the anaesthesiologist should be aware of the interaction of anaesthetic drugs and brainstem function in relation to whole body homeostasis. As a result of this interaction there will be changes in consciousness, protective reflexes, breathing pattern, heart rate, temperature or arterial blood pressure to name a few. Brainstem function can be explored using three different approaches: clinically, analyzing changes in brain electric activity or using neuroimaging techniques. With the aim of providing the clinician anaesthesiologist with a global view of the interaction between the anaesthetic state and homeostatic changes related to brainstem function, the present review article addresses the influence of anaesthetic drug effects on brainstem function through clinical exploration of cranial nerves and reflexes, analysis of electric signals such as electroencephalographic changes and what it is known about brainstem through the use of imaging techniques, more specifically functional magnetic resonance imaging.

Ammonia encephalopathy and awake craniotomy for brain language mapping: cause of failed awake craniotomy.

We report the case of an aborted awake craniotomy for a left frontotemporoinsular glioma due to ammonia encephalopathy on a patient taking Levetiracetam, valproic acid and clobazam. This awake mapping surgery was scheduled as a second-stage procedure following partial resection eight days earlier under general anesthesia. We planned to perform the surgery with local anesthesia and sedation with remifentanil and propofol. After removal of the bone flap all sedation was stopped and we noticed slow mentation and excessive drowsiness prompting us to stop and control the airway and proceed with general anesthesia. There were no post-operative complications but the patient continued to exhibit bradypsychia and hand tremor. His ammonia level was found to be elevated and was treated with an infusion of l-carnitine after discontinuation of the valproic acid with vast improvement. Ammonia encephalopathy should be considered in patients treated with valproic acid and mental status changes who require an awake craniotomy with patient collaboration.

Vía aérea difícil no prevista en un paciente intervenido de artroscopia de hombro con anestesia general y bloqueo interescalénico del plexo braquial / Unexpected difficult airway in a patient during shoulder arthroscopy with general anaesthesia and interscalene brachial plexus block

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The perioperative combination of methadone and ketamine reduces post-operative opioid usage compared with methadone alone.

BACKGROUND: A synergy between ketamine and methadone (ME) to produce antinociception has been demonstrated in experimental neuropathy. We wanted to compare post-operative opioid requirements in patients undergoing multilevel lumbar arthrodesis after the administration combined ME-ketamine (MK) or ME alone. METHODS: This was a randomised double-blind study. During sevoflurane-remifentanil anaesthesia, 11 patients in each group received the following: ketamine bolus (0.5 mg/kg) after tracheal intubation, followed by an infusion of 2.5 µg/kg/min in the MK or saline bolus plus infusion in the ME group. Post-operative analgesia - during 48 h - was provided by patient-controlled analgesia (PCA), delivering bolus containing the following: ME 0.25 mg plus ketamine 0.5 mg in the MK group or ME 0.5 mg in the ME group. Lockout was 10 min, maximum of 3 boluses/h in both groups. Before closing the wound, all the patients received intravenous (i.v.) ME 0.1 mg/kg, dexketoprophen and paracetamol. Pain intensity was evaluated by a numerical rating scale (NRS), on arrival at recovery room (RR) and 24 and 48 h after surgery. In the RR, i.v. ME was administered until NRS was 3 when PCA was started. Dexketoprophen and paracetamol were administered 48 h. RESULTS: Remifentanil requirements were higher in the MK group (P = 0.004). Patients in the MK group received 70% less ME by PCA at 24 h (MK vs. ME group, median and interquartile range) - 3.43 mg (1.9-6.5) vs. 15 mg (9.65-17.38) (P < 0.001) - and at 48 h - 2 mg (0.5-3.63) vs. 9.5 mg (3.5-13.75) (P = 0.001). Patients in the MK group also attempted less doses, at 24 h: 19.5 (12.75-79.5) vs. 98 (41.5-137) (P = 0.043). Both groups had similar NRS values and comparable side effects. CONCLUSIONS: Perioperative ketamine-ME combination significantly decreased opioid consumption by PCA.

Modeling the effect of propofol and remifentanil combinations for sedation-analgesia in endoscopic procedures using an Adaptive Neuro Fuzzy Inference System (ANFIS).

BACKGROUND: The increasing demand for anesthetic procedures in the gastrointestinal endoscopy area has not been followed by a similar increase in the methods to provide and control sedation and analgesia for these patients. In this study, we evaluated different combinations of propofol and remifentanil, administered through a target-controlled infusion system, to estimate the optimal concentrations as well as the best way to control the sedative effects induced by the combinations of drugs in patients undergoing ultrasonographic endoscopy. METHODS: One hundred twenty patients undergoing ultrasonographic endoscopy were randomized to receive, by means of a target-controlled infusion system, a fixed effect-site concentration of either propofol or remifentanil of 8 different possible concentrations, allowing adjustment of the concentrations of the other drug. Predicted effect-site propofol (C(e)pro) and remifentanil (C(e)remi) concentrations, parameters derived from auditory evoked potential, autoregressive auditory evoked potential index (AAI/2) and electroencephalogram (bispectral index [BIS] and index of consciousness [IoC]) signals, as well as categorical scores of sedation (Ramsay Sedation Scale [RSS] score) in the presence or absence of nociceptive stimulation, were collected, recorded, and analyzed using an Adaptive Neuro Fuzzy Inference System. The models described for the relationship between C(e)pro and C(e)remi versus AAI/2, BIS, and IoC were diagnosed for inaccuracy using median absolute performance error (MDAPE) and median root mean squared error (MDRMSE), and for bias using median performance error (MDPE). The models were validated in a prospective group of 68 new patients receiving different combinations of propofol and remifentanil. The predictive ability (P(k)) of AAI/2, BIS, and IoC with respect to the sedation level, RSS score, was also explored. RESULTS: Data from 110 patients were analyzed in the training group. The resulting estimated models had an MDAPE of 32.87, 12.89, and 8.77; an MDRMSE of 17.01, 12.81, and 9.40; and an MDPE of -1.86, 3.97, and 2.21 for AAI/2, BIS, and IoC, respectively, in the absence of stimulation and similar values under stimulation. P(k) values were 0.82, 0.81, and 0.85 for AAI/2, BIS, and IoC, respectively. The model predicted the prospective validation data with an MDAPE of 34.81, 14.78, and 10.25; an MDRMSE of 16.81, 15.91, and 11.81; an MDPE of -8.37, 5.65, and -1.43; and P(k) values of 0.81, 0.8, and 0.8 for AAI/2, BIS, and IoC, respectively. CONCLUSION: A model relating C(e)pro and C(e)remi to AAI/2, BIS, and IoC has been developed and prospectively validated. Based on these models, the (C(e)pro, C(e)remi) concentration pairs that provide an RSS score of 4 range from (1.8 µg·mL(-1), 1.5 ng·mL(-1)) to (2.7 µg·mL(-1), 0 ng·mL(-1)). These concentrations are associated with AAI/2 values of 25 to 30, BIS of 71 to 75, and IoC of 72 to 76. The presence of noxious stimulation increases the requirements of C(e)pro and C(e)remi to achieve the same degree of sedative effects.