Bispectral index as a predictor of unsalvageable traumatic brain injury

Abstract

Introduction The aim was to evaluate the accuracy of bispectral index (BIS) monitoring for the diagnosis of brain death in severely comatose patients. We aimed to determine the utility of the BIS as a tool for clinical evaluation of the moment of brain death. Methods A prospective observational study with waiver of consent was conducted in the trauma ICU for 2 years from October 2012 to September 2014. Monitoring of BIS occurred during patient stay in the ICU. Population: 62 severely comatose patients (Glasgow Coma Score less than 6) admitted to the ICU mainly because of intracerebral hemorrhage, head injury, or postanoxic coma. BIS was recorded continuously during the hospitalization in the ICU. Where necessary, clinical brain death was confirmed by EEG or brain stem test. Results Twenty-nine patients were already clinically brain dead at the time of admission, and their individual BIS values were 0. Twenty-four patients were not clinically brain dead at the time of admission, and their individual BIS values were between 20 and 30. These patients became brain dead, and their individual BIS values dropped to 0 in a few hours to a few days. Seventeen patients who did not become brain dead during their hospitalization in the ICU had persistent electrocerebral activity on EEG, and their average BIS values remained above 31. Conclusion The BIS is a noninvasive, simple, and easy to interpret method, showing a perfect correlation with the other diagnostic methods. BIS can be used in severely comatose patients as an assessment of brain death.