Clinical Evaluation of Two Ke0 in the same Pharmacokinetic Propofol Model: Study on Loss and Recovery of Consciousness

SummaryBackground and objectiveThe constant equilibrium between the plasma and effect site (ke0) is used by pharmacokinetic models to calculate a drug concentration in its site of action (Ce). It would be interesting if Ce of propofol was similar at loss and recovery of consciousness. The objective of this study was to evaluate the clinical performance of two different ke0 (fast = 1.21 min-1, and slow = 0.26 min-1) in relation to Ce during loss and recovery of consciousness using Marsh pharmacokinetic model.MethodsTwenty healthy adult male volunteers participated in this study. In all volunteers propofol was administered as target-controlled infusion, Marsh pharmacokinetic model for fast ke0 and, at a different time, the same pharmacokinetic model with slow ke0 was used. Initially, propofol was infused with a serum target-controlled infusion of 3.0 μg.mL-1. Loss of consciousness and recovery of consciousness were based on response to verbal stimulus. Ce was recorded at the moment of loss and recovery of consciousness.ResultsOn loss and recovery of consciousness, the Ce for fast ke0 was different (3.64 ± 0.78 and 1.47 ± 0.29 μg.mL-1, respectively, p < 0.0001), while with slow ke0 the Ce was similar (2.20 ± 0.70 and 2.14 ± 0.43 μg.mL-1, respectively, p = 0.5425).ConclusionsClinically, the slow ke0 (0.26 min-1) incorporated in the Marsh pharmacokinetic model showed better performance than the fast ke0 (1.21 min-1), since the calculated concentration of propofol at the effect site on loss and recovery of consciousness was similar

Retrospective Analysis of Risk Factors and Predictors of Intraoperative Complications in Neuraxial Blocks at Faculdade de Medicina de Botucatu-UNESP

SummaryBackground and objectivesCardiovascular changes associated with neuraxial blocks are a cause of concern due to their frequency and because some of them can be considered physiological effects triggered by the sympathetic nervous system blockade. The objective of this study was to evaluate intraoperative cardiovascular complications and predictive factors associated with neuraxial blocks in patients ≥ 18 years of age undergoing non-obstetric procedures over an 18-year period in a tertiary university hospital – HCFMB-UNESP.MethodsA retrospective analysis of the following complications was undertaken: hypertension, hypotension, sinus bradycardia, and sinus tachycardia. These complications were correlated with anesthetic technique, physical status (ASA), age, gender, and preoperative co-morbidities. The Tukey test for comparisons among proportions and logistic regression was used for statistical analysis.Results32,554 patients underwent neuraxial blocks. Intraoperative complications mentioned included hypotension (n=4,109), sinus bradycardia (n=1,107), sinus tachycardia (n=601), and hypertension (n=466). Hypotension was seen more often in patients undergoing continuous subarachnoid anesthesia (29.4%, OR=2.39), ≥ 61 years of age, and female (OR=1.27).ConclusionsIntraoperative hypotension and bradycardia were the complications observed more often. Hypotension was related to anesthetic technique (CSA), increased age, and female. Tachycardia and hypertension may not have been directly related to neuraxial blocks

Monitor de profundidade da hipnose. A eletroencefalografia bispectral

JUSTIFICATIVA E OBJETIVOS: A monitorização da profundidade da hipnose e da anestesia é um ato complexo. A maioria das propostas para monitorizar os níveis adequados da hipnose, durante a anestesia, envolve o EEG usando as ondas do EEG, ou mais recentemente, usando a forma processada. A análise bispectral é o método que permite analisar o EEG nas diferentes fases de freqüências. CONTEÚDO: O EEG processado é iniciado com a conversão do sinal de EEG para a forma digital. O EEG digitalizado pode ser matematicamente transformado pelo processo conhecido como análise de Fourier, que separa o complexo sinal do EEG em vários componentes da onda, ou seja, em cada porção de diferente amplitude, mas cuja soma corresponde à forma original da onda. Com o emprego deste método surgem vários parâmetros. O Índice Bispectral, ou simplesmente BIS (100 - acordado até 0 - isoelétrico), é derivado dos melhores parâmetros (p.ex.: freqüência da borda spectral, freqüência mediana e o burst supression ou surto de supressão) que foram avaliados através de análise estatística. CONCLUSÕES: A experiência clínica tem mostrado que o BIS pode predizer uma resposta à incisão da pele durante a anestesia. Entretanto, o BIS não é independente da técnica anestésica usada. Há diferentes respostas, a depender do hipnótico e analgésico empregado.JUSTIFICATIVA Y OBJETIVOS: La supervisión de la profundidad de la hipnosis y de la anestesia es un acto complejo. La mayoría de las propuestas para supervisar los niveles adecuados de la hipnosis, durante la anestesia, envuelven el EEG usando las ondas del EEG, o más recientemente, usando la forma procesada. La análisis bispectral es el método que permite analizar el EEG en las diferentes fases de frecuencias. CONTENIDO: El EEG procesado es iniciado con la conversión del señal de EEG para la forma digital. El EEG digitalizado puede ser matemáticamente transformado por el proceso conocido como análisis de Fourier, que separa el complejo señal del EEG en varios componentes de la onda, o sea, en cada porción de diferentes amplitudes, mas, cuja suma, corresponde a la forma original de la onda. Con el empleo de este método surgen varios parámetros. El Índice Bispectral, o simplemente BIS (100-acordado hasta 0- isoeléctrico) es derivado de los mejores parámetros (p.ej.: frecuencia de la borda spectral, frecuencia mediana y el burst supression o surto de supresión) que fueron evaluados a través de análisis estadística. CONCLUSIONES: La experiencia clínica ha mostrado que el BIS puede predecir una respuesta a la incisión de la piel durante la anestesia. Entretanto, el BIS no es independiente de la técnica anestésica usada. Hay diferentes respuestas, a depender del hipnótico y analgésico utilizado.BACKGROUND and OBJECTIVES: Monitoring the depth of anesthesia is a complex process. Most approaches to monitoring anesthetic adequacy involve EEG waves or, more recently, some EEG processed form. Bispectral analysis is a method which allows for EEG analysis in different frequency phases. CONTENTS: Processed EEG starts with the digitalization of the EEG signal. The digitized EEG can then be mathematically transformed by a process known as Fourier analysis, which divides the complex EEG signal in a number of sine wave components, that is, in each portion of different amplitude, but whose sum corresponds to the original EEG waveform. Many parameters are derived from this method. Bispectral index, or simply BIS (100 = awaken to 0= EEG isoelectric) is derived from the best parameters (e.g. spectral edge frequency, median frequency and burst suppression) which are evaluated by statistical analysis. CONCLUSIONS: Clinical experience has shown that BIS may predict a response to skin incision during anesthesia. However, BIS is not independent of the anesthetic technique. There are different responses depending on which hypnotics or analgesics are used