Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942001000500008
Brazilian Journal of Anesthesiology
Miscellaneous

Monitor de profundidade da hipnose. A eletroencefalografia bispectral

Monitoring the adequacy of hipnosis by bispectral index

Pedro Thadeu Galvão Vianna

http://dx.doi.org/10.1590/S0034-70942001000500008 Braz J Anesthesiol, vol.51, n5, p.418-425, 2001
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Resumo

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.

Palavras-chave

MONITORIZAÇÃO, MONITORIZAÇÃO

Abstract

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.

Keywords

MONITORING, MONITORING

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