Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942003000100001
Brazilian Journal of Anesthesiology
Scientific Article

Avaliação dos parâmetros derivados do eletroencefalograma durante administração de diferentes concentrações de óxido nitroso

Evaluation of electroencephalographic parameters during the administration of different nitrous oxide concentrations

Sara Lúcia Cavalcante; Rogean Rodrigues Nunes

http://dx.doi.org/10.1590/S0034-70942003000100001 Braz J Anesthesiol, vol.53, n1, p.1-8, 2003
PDF
Downloads: 0
Views: 1036

Resumo

JUSTIFICATIVA E OBJETIVOS: A análise espectral do eletroencefalograma vem sendo usada como medida da profundidade anestésica, nível de hipnose e sedação de diversos agentes anestésicos. O objetivo deste estudo foi avaliar os efeitos do N2O sobre os parâmetros derivados do eletroencefalograma, nível de sedação pela Escala Analógica de Alerta e Sedação (EAS), variáveis hemodinâmicas e ventilatórias. MÉTODO: Participaram do estudo 30 pacientes adultos, de ambos os sexos, estado físico ASA I, com idades entre 20 e 40 anos, que se submeteram ao seguinte protocolo: respirar espontaneamente e relaxar de olhos fechados durante dez minutos, sendo coletados dados em três momentos: M1 - antes da oferta de N2O; M2 - N2O a 30% em O2; M3 - N2O a 50% em O2. A coleta dos dados de M2 e M3 foi realizada após quinze minutos da estabilização das frações expiradas de N2O (FeN2O) em 30% e 50% respectivamente, com o tempo de 5 minutos entre as frações. Os parâmetros estudados foram os seguintes: eletroencefalográficos: BIS, SEF1, SEF2, potência total (PT) e taxa de supressão (TS); hemodinâmicos: freqüência cardíaca (FC), pressão arterial sistólica (PAS), pressão arterial diastólica (PAD); ventilatórios: SpO2, P ET CO2, ventilação minuto e freqüência respiratória; clínicos: os pacientes foram classificados numericamente em ordem decrescente (5, 4, 3, 2 e 1) quanto ao seu estado de alerta, pela EAS. RESULTADOS: O N2O a 30% e a 50% modificou estatisticamente o BIS, SEF1, SEF2, PT e o grau de sedação pela EAS, ao longo dos momentos estudados. Não foram observadas modificações clinicamente importantes, pois todos os pacientes mostraram-se cooperativos e levemente sedados, apesar das variações do SEF1 e SEF2 indicarem valores compatíveis com estágio de hipnose profunda. As variações estatísticas nos parâmetros hemodinâmicos e ventilatórios não foram clinicamente significativas. CONCLUSÕES: O N2O a 30% e a 50%, em pacientes sem medicação pré-anestésica, induzem a um leve estado de sedação avaliado pela EAS, havendo correspondência com o BIS, o mesmo não ocorrendo com SEF1 e SEF2.

Palavras-chave

ANESTÉSICOS, ANESTÉSICOS, MONITORIZAÇÃO, MONITORIZAÇÃO, MONITORIZAÇÃO, MONITORIZAÇÃO, MONITORIZAÇÃO

Abstract

BACKGROUND AND OBJECTIVES: Spectral electroencephalography has been used to measure anesthetic depth, hypnosis and sedation levels induced by different anesthetic agents. This study aimed at evaluating the effects of N2O on electroencephalographic (EEG) variables and sedation levels according to Observer Assessment of Alertness/Sedation (OAA/S) scale, as well as on hemodynamic and respiratory parameters. METHODS: Thirty adult patients from both genders, physical status ASA I, aged 20 and 40 years, were submitted to the following protocol: after 10 minutes of relaxation, spontaneously breathing with eyes close, patients were given 30% and 50% N2O concentrations under face mask. Data were collected in three moments: M1- before N2O administration; M2 - 30% N2O in O2; M3 - 50% N2O in O2. Data for M2 and M3 were collected 15 minutes after stabilization of 30% and 50% N2O expired fractions (FeN2O), respectively, with a 5-minute interval between fractions. The following parameters were evaluated: electroencephalographic: BIS, SEF1, SEF2, power energy (PE) and burst suppression (BS); hemodynamic: heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP); respiratory: oxygen hemoglobin saturation (SpO2), carbon dioxide expired pressure (P ET CO2), minute ventilation and respiratory rate; clinical: patients were rated in a descending order (5, 4, 3, 2 and 1) according to OAA/S scale. RESULTS: N2O administrated at 30% and 50% concentrations has statistically changed BIS, SEF1, SEF2, PE and OAA/S level of sedation in the studied moments. No clinically important changes were observed, as all patients were cooperative and slightly sedated, though SEF1 and SEF2 indications of deep hypnosis. Hemodynamic and respiratory parameters changes were not statistically significant. CONCLUSIONS: N2O at 30% and 50% concentrations in non-premedicated patients has induced mild sedation according to OAA/S scale. There has been correspondence with BIS, but not with SEF1 and SEF2.

Keywords

ANESTHETICS, ANESTHETICS, MONITORING, MONITORING, MONITORING, MONITORING, MONITORING

References

Cahalan MK, Prakash O, Rulf . Addition of nitrous oxide to fentanyl anesthesia does not induce myocardial ischemia in patients with ischemic heart disease. Anesthesiology. 1987;67:925-929.

Notini-Gudmarsson AK, Dolk A, Jakobsson J. Nitrous oxide: a valuable alternative for pain relief and sedation during routine colonoscopy. Endoscopy. 1996;28:283-287.

Wilson S. A survey of the American Academy of Pediatric Dentistry membership; nitrous oxide and sedation. Pediatr Dent. 1996;18:287-293.

Cheung AT, Longnecker DE. Pharmacology of Inhalational Anesthetics. - Principles and Practice of Anesthesiology. 1998:1123-1157.

Tomi K, Mashimo T, Tashiro C. Alterations in pain threshold and psychomotor response associated with subanaesthetic concentrations of inhalation anesthetics in humans. Anesthesiology. 1993;70:684-686.

Dwyer R, Bennett HL, Eger II EI. Effects of isoflurane and nitrous oxide in subanesthetic concentrations on memory and responsiveness in volunteers. Anesthesiology. 1992;77:888-898.

Rampil IJ, Kim JS, Lenhardt R. Bispectral EEG Index during nitrous oxide administration. Anesthesiology. 1998;89:671-677.

Ebert TJ. Differential effects of nitrous oxide on baroreflex control of heart rate and peripheral sympathetic nerve activity in humans. Anesthesiology. 1990;72:16-22.

Ebert TJ, Kampine JP. Nitrous oxide augments sympathetic outflow: direct evidence from human peroneal nerve recordings. Anesth Analg. 1989;69:444-449.

Hornbein TF, Eger II El, Winter PM. The minimum alveolar concentration of nitrous oxide in man. Anesth Analg. 1982;61:553-556.

Yamamura T, Fukuda M, Takeya H. Fast oscillatory EEG activity induced by analgesic concentrations of nitrous oxide in man. Anesth Analg. 1981;60:283-288.

Nunes RR, Cavalcante SL, Ibiapina RC. Effects of sevoflurane plus fentanyl in hemodynamic, endocrine and electroencephalographic responses to tracheal intubation. Br J Anesthesiol Int Issue. 2001;12:1-6.

Kearse LAJ, Rosow C, Zaslavsky A. Bispectral analysis of the electroencephalogram predicts conscious processing of information during propofol sedation and hypnosis. Anesthesiology. 1998;88:25-34.

Glass PSA, Bloom M, Kearse I. Bispectral analysis measures sedation and memory effects of propofol, midazolam, isoflurane and alfentanil in healthy volunteers. Anesthesiology. 1997;86:846-847.

Nunes RR, Cavalcante Sl, Zeferino T. Influência da clonidina na anestesia inalatória com sevoflurano em adultos: Avaliação pelo índice bispectral. Rev Bras Anestesiol. 1999;49:89-93.

Chernik DA, Gillings D, Laine H. Validity and reliability of the observer's assessment of alertness/sedation scale: study with intravenous midazolam. J Clin Psychopharmacol. 1990;10:244-251.

Schwender D, Daunderer M, Klasing S. Power spectral analysis of the electroencephalogram during increasing end-expiratory concentrations of isoflurane, desflurane and sevoflurane. Anaesthesia. 1998;53:335-342.

Rampil IJ. A primer for EEG signal processing in anesthesia. Anesthesiology. 1998;89:980-1002.

Parbrook GD. Therapeutic use of nitrous oxide: a review. Br J Anaesth. 1968:366-372.

Galinkin JL, Janiszewski D, Young CJ. Subjective, psychomotor, cognitive and analgesic effects of subanesthetic concentrations of sevoflurane and nitrous oxide. Anesthesiology. 1997;87:1082-1088.

Henrie JR, Parkhouse J, Bickford RG. Alterations of human consciousness by nitrous oxide as assessed by eletroencepha- lography and psychological test. Anesthesiology. 1961;22:247-259.

Cook TL, Smith M, Starkweather JA. Behavioral effects of trace and subanesthetic halothane and nitrous oxide en man. Anesthesiology. 1978;49:419-424.

Dwyer R, Bennett HL, Eger II El. Effects of isoflurane and nitrous oxide in subanesthetic concentrations on memory and responsiveness in volunteers. Anesthesiology. 1992;77:888-898.

Hans P, Bonhomme V, Benmansour H. Effect of nitrous oxide on the bispectral index and the 95% spectral edge frequency of the electroencephalogram during surgery. Anaesthesia. 2001;56:999-1002.

5ddd3a170e882536151da3e9 rba Articles
Links & Downloads
2352-2291 (Electronic) 0104-0014 (Printed)
Braz J Anesthesiol ©2024 All rights reserved.

Braz J Anesthesiol

Share this page
Page Sections