Electroencephalographic density spectral array monitoring during propofol/sevoflurane coadministration in children, an exploratory observational study

INTRODUCTION

Propofol and sevoflurane have a long history in pediatric anesthesia. Combining both drugs at low dose levels offers new opportunities. However, monitoring the hypnotic effects of this drug combination in children is challenging, because the currently available processed EEG-based systems are insufficiently validated in young children and the co-administration of anesthetics. This study investigated electroencephalographic density spectral array monitoring during propofol/sevoflurane coadministration with fixed sevoflurane- and variable propofol dosages.

PATIENTS AND METHODS

We analyzed the density spectral array pattern recorded during propofol/sevoflurane anesthesia in pediatric patients from birth to 11 years of age. Data from 78 patients were suitable for analysis. The primary outcome parameter of this study was the correlation between variable propofol dosages and the expression of the four electroencephalogram frequency bands β, α, θ, and δ. The main secondary outcome parameters were the intra-operative total EEG power and the prevalence of burst suppression.

RESULTS

In patients above the age of 1 year, a dose-dependent correlation between the propofol dosage and the relative percentage of β (-12.2%, p < 0.001) and δ (5.1%, p < 0.001) was found. There was an age-dependent trend toward increasing mean EEG power, with the most significant increase in the first year of life. In 14.1% of our patients, at least one episode of burst suppression occurred.

CONCLUSION

DSA-guided augmentation of propofol anesthesia with sevoflurane provides sufficient depth of anesthesia at doses usually considered sub-anesthetic in children, leading to less anesthetic drug exposure for the individual child.

Usability of the SedLine® electroencephalographic monitor of depth of anaesthesia in pigs: a pilot study

To investigate the usability of the SedLine® monitor in anaesthetized pigs. Five juvenile healthy pigs underwent balanced isoflurane-based general anaesthesia for surgical placement of a subcutaneous jugular venous port. The SedLine® was applied to continuously monitor electroencephalographic (EEG) activity and its modulation during anaesthesia. Computer tomography and magnetic resonance were performed to investigate the relationship between electrodes' positioning and anatomical structures. The pediatric SedLine® EEG-sensor could be easily applied and SedLine®-generated variables collected. An EEG Density Spectral Array (DS) was displayed over the whole procedure. During surgery, the EEG signal was dominated by elevated power in the delta range (0.5-4 Hz), with an underlying broadband signal (where power decreased with increasing frequency). The emergence period was marked by a decrease in delta power, and a more evenly distributed power over the 4-40 Hz frequency range. From incision to end of surgery, mean SedLine®-generated values (± standard deviation) were overall stable [23.0 (± 2.8) Patient State Index (PSI), 1.0% (± 3.8%) Suppression Ratio (SR), 8.8 Hz (± 2.5 Hz) Spectral Edge Frequency 95% (SEF) left, 7.7 Hz (± 2.4 Hz) SEF right], quickly changing during emergence [75.3 (± 11.1) PSI, 0.0 (± 0.0) SR, 12.5 (± 6.6) SEF left 10.4 (± 6.6) SEF right]. Based on the imaging performed, the sensor does not record EEG signals from the same brain areas as in humans. SedLine®-DSA and -generated variables seemed to reflect variations in depth of anaesthesia in pigs. Further studies are needed to investigate this correlation, as well as to define the species-specific brain structures monitored by the EEG-sensor.

Evaluation of the density spectral array in the Wada test: report of six cases

Wada test is an invasive procedure used in the preoperative evaluation for epilepsy surgery to determine language lateralization, postoperative risk of amnesia syndrome, and to assess the risk of memory deficits. It involves injection of amobarbital into internal carotid artery of the affected hemisphere followed by the healthy hemisphere to shut down brain function. We performed an observational study evaluating the density spectral array (DSA) of the bilateral bispectral index VISTA™ Monitoring System (BVMS) in 6 patients with drug-resistant epilepsy undergoing Wada test. DSA revealed the presence of bifrontal alpha waves in absence of loss of consciousness in all patients.

Use of Processed Electroencephalography in the Clinical Setting

Purpose of Review

Processed electroencephalography (pEEG) is widely used in clinical practice. Few clinicians utilize the full potential of these devices. This brief review will address the improvements in patient management available from the utilization of all pEEG data.

Recent Findings

Anesthesiologists easily learn to recognize raw pEEG patterns that are consistent with an appropriate level of hypnotic effect. Power distribution within the waveform can be displayed in a visual format that identifies signatures of the principal anesthetic hypnotics. Opinion on the benefit of pEEG data in the mitigation of postoperative neurological impairment remains divided.

Summary

Looking beyond the index number can aid clinical decision making and improve confidence in the benefits of this monitoring modality.

Density spectral array of BIS VISTA™ monitoring system in a functional hemispherectomy

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) VISTA^TM 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.

Changes in bilateral bispectral index VISTA monitoring system during Wada test

The Wada test is a procedure used in the preoperative assessment before epilepsy surgery in order to determine language lateralization, to assess the post-operative risk of an amnesia syndrome, and to evaluate the risk of material-specific memory deficits, in particular verbal memory deficits. This test involves inserting a cannula into the internal carotid artery via the femoral artery, and then to inject amobarbital to shut down brain function, usually in one of the brain hemispheres. The bilateral bispectral index (BIS) VISTA™ monitoring system (BVMS) was used to detect changes in EEG, and in the power spectrum distribution using the density spectral array (DSA) of both hemispheres. We describe a patient with an agenesis of the A1 segment of the right anterior cerebral artery, scheduled for a Wada test, in whom the BVMS demonstrated its potential value.