BIS in Critically Ill Patients in ICU

The Bispectral Index (BIS) is a monitor that converts brain electrical activity from EEG into a simple number from 0 to 100. A higher number means the patient is more awake, while a lower number means deeper sedation or reduced brain activity.

In general, 100 means fully awake, 80 suggests light to moderate sedation, 60 is commonly used as a target for general anesthesia with a low chance of awareness, 40 indicates deep anesthesia, 20 suggests marked brain suppression with burst suppression on EEG, and 0 indicates no detectable cortical electrical activity.

Although BIS was originally developed for use in the operating room, it has also been applied in the ICU to help guide sedation, avoid over- or under-sedation, and assess consciousness in patients who cannot be evaluated reliably using standard clinical scores. BIS has also been studied as a possible tool for predicting outcomes in comatose ICU patients, such as those after cardiac arrest, stroke, encephalitis, or traumatic brain injury. However, evidence is still limited for its use in predicting outcomes among ICU patients with any form of decreased consciousness. Therefore, this study was conducted to explore that role.