Bolus administration of intravenous anesthetic, recent changes in inhalation anesthesia or administration of adjuvant agents (beta blockers, alpha 2 agonists) can all result in acute decrease in BIS™ numbers.
Why does my BIS™ monitor number suddenly increase?
An abrupt change in the BIS™ may reflect a new cortical state relative to anesthetic dosing and changes in surgical conditions. High frequency artifacts (EMG, electrocautery or high frequency signals) my contaminate the EEG signal and bias the BIS™ toward a higher value. Additionally, the BIS™ may show a transient increase in response to noxious stimulation.
Why doesn’t my sensor stay in place for the entire case?
Prior to application of the sensor, make sure to wipe the skin with an alcohol pad and dry thoroughly. After applying the sensor, make sure to press the edges of the sensor to ensure adhesion. Circle all four elements/circles to seal in the gel. Press each element/circle for five seconds to ensure proper contact.
What should my suppression ratio reading be vs. burst suppression?
The percentage of epochs in the past 63 seconds in which the EEG signal is considered suppressed (0-100%). Burst count is the number of EEG bursts per minute, where a burst is defined as a short period of EEG activity preceded and followed by periods of inactivity – suppression (0-20).
What is the ideal setting for the smoothing rate?
The BIS™ system offers three choices of smoothing rates over which the BIS™ value is averaged. There are three default settings based on monitor mode. For Monitor Mode I and IV, the default setting is 15 seconds. For Monitor Mode II, it is 30 seconds and Monitor Mode III is 10 seconds.
When and why would you use BIS™ monitoring?
The BIS™ monitor is intended for use on adult and pediatric patients within a hospital or medical facility providing patient care to monitor the state of the brain by data acquisition of EED signals. It may be used to help guide anesthetic administration and may be associated with the reduction of the incidence of awareness with recall in adults during anesthesia and sedation.
Why is there so much EMG?
This frequency range contains power from muscle activity -- electromyography or EMG, as well as, power from other high-frequency artifacts. When the BIS™ indicator bar is low, it indicates that EMG activity is low. BIS™ monitoring conditions are optimal when the bar is empty. One bar represents power in the 30–38 range; two bars represent power in the 39–47 range; three bars represent power in the 48–55 range and 4 bars represent power greater than 55.
Why is my BIS™ monitor value high when I know my patient is asleep?
Observe for the presence of artifacts such as EMG, electrocautery or high frequency signals. High frequency artifacts including those listed, may contaminate the EEG signal and bias the BIS™ monitor towards a higher value. Ensure that anesthetic delivery systems are operating properly so that the intended dose of anesthetic agent is reaching the patient. Changes in vaporizer setting, fresh gas flow rates, intravenous infusion pump setting, and intravenous delivery routes may account for a sudden change in level of anesthetic effect and the resulting BIS™ value. Ensure that the anesthetic dose is sufficient. An abrupt change in the BIS™ value may reflect a new cortical state relative to anesthetic dosing and changes in surgical conditions. Assess the current level of surgical stimulation. The BIS™ monitor may show a transient increase in response to increases in noxious stimulation.
I push really hard on the sensor to get the gel pack to break, but it still doesn’t, why?
If you push too hard and the zip prep breaks, the sensor may not work. Prep the skin by wiping with an alcohol pad and allow to dry thoroughly. Apply the sensor to the forehead. Starting with circle # 1, center the sensor on the forehead, approximately 2 inches (5cm) above the nose or 1.5 inches (4cm) for a pediatric sensor. Place circle # 4 directly above and adjacent to the eyebrow. Place circle # 3 on either temple area between the corner of the eye and the hairline. Press the edges of the sensor to ensure adhesion. Circle all four elements/circles to seal the gel. Press each circle for five seconds to ensure proper contact. Use a fingertip to press each circle one at a time. Press firmly to adhere the sensor to skin.
What does the signal quality mean?
The Signal Quality Indicator (SQI) is a measure of the signal quality for the EEG channel source and is calculated based on impedance data, artifact, and other variables. It is displayed in the upper left corner of the screen, to the right of the “BIS” label. Signal quality is optimal when all five bars of the SQI icon are green. When signal quality is too low to accurately calculate a BIS™ value, the BIS™ value and other trend variables that are adversely affected by artifact, will not be displayed on the screen.