What is burst suppression in EEG?
Burst suppression is an electroencephalography (EEG) pattern that is characterized by periods of high-voltage electrical activity alternating with periods of no activity in the brain. The pattern is found in patients with inactivated brain states, such as from general anesthesia, coma, or hypothermia.
What is seizure burst suppression?
Burst suppression is defined as an electroencephalography finding consisting of a continuous alternation between of high-voltage slow waves (burst) and periods of depressed electrical activity [10].
How do you induce a burst suppression?
A BSP can be induced by anesthetics and hypothermia. Anesthetics can be used to induce burst-suppression in the treatment of super-refractory status epilepticus. When it occurs after cardiac arrest, the BSP predicts a poor prognosis.
Does propofol cause burst suppression?
In vitro studies of thiopental, propofol, and isoflurane show that these anesthetics potentiate GABAA receptors. The activation of these receptors leads to a burst suppression pattern, and further increasing the anesthetic concentration depresses glutamatergic transmission.
What is suppression ratio?
The Suppression Ratio trend displays a running average of the percentage of EEG activity that falls below a user-specified amplitude threshold, as a function of time. In the case of refractory status epilepticus, the patient is sometimes treated with medications aiming to induce suppression-burst activity in the EEG.
What is suppression ratio BIS?
BIS monitoring The Burst Suppression Ratio (BSR) is defined as the percentage of epochs in the previous 63 seconds in which the EEG signal is considered suppressed [18]. Suppression is recognized as those periods longer than 0.5 seconds, during which the EEG voltage does not exceed approximately ± 5 μV [18,19].
Does propofol cause burst suppression on EEG?
Burst suppression can be clearly observed in both the time and frequency domains. This is exemplified in Figure 1, which shows EEG recordings from a healthy volunteer under propofol-induced anesthesia with the propofol dose increased in a stepwise fashion (Purdon et al., 2013).
How does propofol affect EEG?
Moderate propofol sedation increases EEG oscillations in the spindle range (12–15 Hz) and beta range (13–25 Hz) in frontal areas, and deep sedation is associated with delta oscilla- tions across the cortex and alpha anteriorization[11].
How do you calculate suppression ratio?
If A is the response rate during CS and B is the response rate in the absence of the CS (usually measured immediately prior to CS presentation) then the suppression ratio is A/(A+B).
What does a suppression ratio of .5 mean?
• Normally between 0 and .5 (for suppression) – 0 means. (0 / 0+40) = 0. – .5 means. (40 / 40 + 40) = .5.
What is normal BIS?
BIS values range from 0 to 100. A value of 0 represents the absence of brain activity, and 100 represents the awake state. BIS values between 40 to 60 represent adequate general anesthesia for a surgery, values less than 40 represent a deep hypnotic state.
What does burst suppression really mean?
The term burst suppression describes an electroencephalographic (EEG) pattern consisting of a continuous alternation between high-voltage slow waves (occasionally sharp waves) and depressed (or suppressed) electrographic activity.
What is the significance of burst suppression?
Burst suppression helps to decrease metabolic demand so that the cerebral tissue can better tolerate induced ischemia, such as during temporary clipping.
What is background suppression on EEG?
Background suppression is a more severe attenuation , a progression from burst suppression patterns, which indicates complete or almost complete disappearance of EEG activity. It is defined by background activity consisting of amplitudes less than 10 microvolts (see image below).