BIS在小儿监测中的研究进展

目前，脑电双频谱指数（BIS）已被广泛应用于成人镇静状态与麻醉深度的监测，但小儿大脑发育成熟度与成人比有一定差异，因此BIS在小儿监测的应用特性备受关注。通过对这一领域研究现状进行综述以供参考。     

Bispectral EEG Index during Nitrous Oxide Administration

Background: Nitrous oxide (N2 O) is a commonly used sedative for painful diagnostic procedures and dental work. The authors sought to characterize the effects of N2 O on quantitative electroencephalographic (EEG) variables including the bispectral index (BIS), a quantitative parameter developed to correlate with the level of sedation induced by a variety of agents.

Methods: Healthy young adult volunteers (n = 13) were given a randomized sequence of N2 O/O2 combinations via face mask. Five concentrations of N2 O (10, 20, 30, 40, and 50% atm) were administered for 15 min (20 min for the first step). EEG was recorded from bilateral frontal poles continuously. At the end of each exposure, level of sedation was assessed using primarily the Observer Assessment of Alertness/Sedation (OAA/S) scale.

Results: One subject withdrew from the study because of emesis at 50% N (2) O. N2 O (50%) increased theta, beta, 40 - 50 Hz, and 70 - 110 Hz band powers. BIS and spectral edge frequency during 50% N2 O/O2 did not differ significantly from baseline values. Abrupt decreases from higher to lower concentrations frequently evoked a profound, transient slowing of activity. No significant change in OAA/S was detected during the study.     

The Bispectral Index in children: comparing isoflurane and halothane

Background. The Bispectral Index (BIS) has been calibrated forseveral general anaesthetic agents including isoflurane. Halothaneis still used in paediatric anaesthesia. Compared with othervolatile anaesthetics, halothane has a different receptor affinityand differing effects on the EEG. There are limited data evaluatingthe BIS with halothane. We set out to compare the BIS usinghalothane and isoflurane at a clinically relevant equipotentconcentration (1 MAC) and at a reproducible measure of anaestheticeffect (awakening). Methods. Forty children aged between 2 and 15 yr were enrolledin a masked randomized trial—20 in each group. Anaesthesiawas induced with sevoflurane or propofol. Either halothane orisoflurane were given to obtain an end-tidal concentration of1 MAC for 15 min. The BIS was then recorded. The BIS was alsorecorded at awakening. Values (mean (SD)) were compared witha t test. Results. At 1 MAC the BIS for halothane was significantly greaterthan isoflurane (56.5 (8.1) vs 35.9 (8.5), P<0.0001). Atawakening there was no significant difference (BIS halothane;81.1 (11.9), BIS isoflurane; 82.5 (16.4)). The difference inmeans at awakening was 1.4 (95% CI –8.2 to 11.1). Conclusions. At equipotent concentrations of halothane and isofluraneBIS valves were significantly greater with halothane. At awakeningthe BIS values were equivalent for each agent. This findingis consistent with the BIS being more affected by the agentused at higher concentrations of anaesthetic. The BIS must beinterpreted with caution when using halothane. Br J Anaesth 2004; 92: 14–17     

脑电双频指数监测在临床特殊情况中的应用

随着临床监测控术的发展，脑电监测有望成为临床麻醉，急诊及重症监护病房的常规监测手段，其中研究较多的脑电双频指数（BIS）已在麻醉诱导，维持，恢复等方面显示出优势。近年也有研究报道在特殊情况下应用BIS监测，包括在颅脑损伤，低温体外循环，心跳骤停等，为临床更深一步应用BIS提供了帮助。     

Comparative evaluation of Bispectral Index and Narcotrend Index in children below 5 years of age

BACKGROUND: The use of electroencephalogram (EEG) monitoring devices for assessing the depth of hypnosis is most difficult in children under 5 years of age. METHODS: Forty five children aged 0-60 months were included in a prospective observational study. A direct comparison of the processed EEG variables Bispectral Index (BIS, version 3.4) and Narcotrend Index (NI, version 2.0AF) was to be achieved by simultaneous recording. The ability of these parameters to differentiate between various clinical states was evaluated by using the prediction probability (P(k)). Age-related effects on the BIS and NI were analyzed by dividing the children into three age groups: 0-6, 7-18 and 19-60 months. RESULTS: The preanesthesia, conscious children were differentiated from anesthetized patients by the BIS and NI with no overlap (P(k) = 1.0). In the awake period the BIS was superior to the NI (P(k) to differentiate 'end of anesthesia' from 'awakening' was 0.97 vs 0.73 respectively; P = 0.002). Patients aged 7-18 months showed higher BIS and NI values in the course of anesthesia than the younger and older children (P = 0.001). On awakening, children aged 0-6 months showed the lowest mean BIS (n.s.) and NI (P = 0.006) values. CONCLUSIONS: The BIS currently seems to be superior to the NI, but age-related processing algorithms of the raw EEG must be implemented in both BIS and NI in order to be useful in children younger than 5 years of age.     

Bispectral Index asymmetry and COMFORT score in paediatric intensive care patients

BACKGROUND: The Bispectral Index (BIS) monitor has been suggested as a potential tool to measure depth of sedation in paediatric intensive care unit (PICU) patients. The primary aim of our observational study was to assess the difference in BIS values between the left and right sides of the brain. Secondary aims were to compare BIS and COMFORT score and to assess change in BIS with tracheal suctioning. METHODS: Nineteen ventilated and sedated PICU patients had paediatric BIS sensors applied to either side of their forehead. Each patient underwent physiotherapy involving tracheal suctioning. Their BIS data and corresponding COMFORT score, assessment as by their respective nurses, were recorded before, during, and after physiotherapy. RESULTS: Seven patients underwent more than one physiotherapy session; therefore, 28 sets of data were collected. The mean BIS difference values (and 95% CI) between left BIS and right BIS for pre-, during, and post-physiotherapy periods were 9.2 (5.9-12.5), 15.8 (11.9-19.7), and 7.5 (5.2-9.7), respectively. Correlation between mean BIS, left brain BIS, and right brain BIS to COMFORT score was highly significant (P<0.001 for all three) during the pre- and post-physiotherapy period, but less so during the stimulated physiotherapy period (P=0.044, P=0.014, and P=0.253, respectively). CONCLUSIONS: A discrepancy between left and right brain BIS exists, especially when the patient is stimulated. COMFORT score and BIS correlate well between light and moderate sedation.     

脑电双频指数用于小儿镇静及麻醉深度监测的研究进展

大量研究证实,脑电双频指数(BIS)与较大小儿的镇静及麻醉深度有较好的相 关性,与麻醉药物浓度呈负相关,能较好地评价意识水平。但对于婴儿,BIS监测的有效性尚 有待于进一步研究。     

Low baseline Bispectral Index of the electroencephalogram in patients with dementia

The baseline value of the Bispectral Index (BIS) is 96-99 in the awake state. Patients with Alzheimer's disease or vascular dementia may show an increase in slow wave and a decrease in fast wave activity of the electroencephalogram (EEG). BIS is presumed to decrease with EEG slowing. We hypothesized that the baseline "awake" BIS is lower in dementia than in normal elderly patients. We studied 36 patients with Alzheimer's disease or multiinfarct dementia and 36 control patients aged >75 yr. Both groups were assessed with a Mini-Mental State Test. BIS (version 3.4) was recorded from a frontal derivation using an Aspect A-2000 EEG monitor. Off-line data analysis was also performed with the newer version 4.0 of the BIS algorithm. Fourteen of 36 (38%) dementia patients and 4 of 36 (11%) controls had mean baseline BIS 3.4 <93 (P = 0.006). Eighteen of 36 (50%) dementia patients and 8 of 36 (22%) controls had mean BIS 4.0 <93 (P = 0.026). Mean (95% confidence interval) BIS 3.4 was 92.9 (91-95) in the dementia and 96.1 (95-97) in the control group (P = 0.02). Values with BIS 4.0 were, respectively, 89.1 (86-92) and 94.7 (93-96) (P = 0.002). No significant difference was found in age, sex, activity from the electromyogram, and signal quality index. As expected, the difference in Mini-Mental State Test scores was significant (P < 0.0001). A significant proportion of patients with dementia shows a low baseline BIS. The utility of the BIS monitor in detecting dementia warrants further investigation. IMPLICATIONS: This prospective, controlled, observational study demonstrates that electroencephalogram slowing associated with dementia affects the Bispectral Index of the electroencephalogram. A significant proportion of patients with dementia have a lower than normal "awake" Bispectral Index.     

IV ATP Potentiates Midazolam Sedation as Assessed by Bispectral Index

In this study, by measuring bispectral index (BIS), we tested the hypothesis that intravenous adenosine 5′-triphosphate (ATP) infusion would deepen the level of midazolam-induced sedation. Ten healthy volunteers underwent 2 experiments with at least 2 weeks'' interval: immediately after intravenous bolus administration of midazolam (0.04 mg/kg), they received continuous infusion of either ATP infusion (100 μg/kg/min) or placebo (saline) for 40 minutes in a double-blind, randomized, crossover manner. Changes in BIS values and responsiveness to verbal command as well as cardiorespiratory variables were observed throughout the study periods. Administration of midazolam alone reduced BIS value from control: 97 ± 1 to 68 ± 18 at 25 minutes, which was accompanied by significant cardiopulmonary depressant effects, while maintaining responsiveness to verbal command (consciousness) throughout the study period. Coadministration of ATP with midazolam further reduced BIS value to 51 ± 13, associated with complete loss of consciousness without adverse effect on the cardiorespiratory systems. We conclude that the addition of ATP infusion to midazolam significantly enhances midazolam sedation without disturbing cardiorespiratory functions.Key Words: Midazolam sedation, ATP, Central adenosine receptorsIntravenous (IV) adenosine 5′-triphosphate (ATP) infusion has been used for various clinical indications.¹ However, when ATP is infused intravenously, it is rapidly broken down into adenosine. Thus, we assumed that ATP would act in a similar fashion to adenosine. Adenosine is an endogenous neuromodulator that is capable of inducing sedation and sleep. There is good evidence that adenosine is an endogenous sleep-promoting molecule.^2,3 Further, a low dose of adenosine infusion (80–140 μg/kg/min) in humans has been shown to stimulate cardiorespiratory systems.^4–6 Meanwhile, the bispectral index (BIS) was reported to provide a reliable measure of the hypnotic effect of midazolam, and BIS analysis can indicate the depth of midazolam sedation.^7,8 Previously, we have shown that coadministration of ATP with midazolam significantly enhanced the hypnotic effect of midazolam in humans, as assessed by subjective and objective questionnaire.⁹ In this study, we examined the effect of ATP infusion on midazolam-induced sedation by continuous measurement of BIS and responsiveness to verbal command as well as cardiorespiratory responses. Furthermore, we sought to find the potential beneficial and/or adverse effects of ATP infusion when combined with midazolam in healthy human volunteers.