Comparison between clinical tests and the Cerebral State Index or brain death determination

Introduction

Diagnosis of brain death is very important. Confirmatory tests have been used to corroborate brain death, but they are expensive, nonattainable in all ICUs and in some instances have no correlation with clinical tests [1]. The Cerebral State Index (CSI) (Danmeter, Odense, Denmark) is a portable apparatus that has been made for determination of the depth of anesthesia based on brain waves determination and analysis [2].

Methods

This is a study on 65 head-injured patients and 72 alert head-injured patients. Eighteen to 24 hours after confirmation of brain death by clinical tests applied by a neurologist, the CSI was recorded according to the company's instruction. The CSI was recorded if the electromyography was zero on the screen and the quality index was above 70%.

Results

If the CSI score was ≤ 3 for detection of brain death and the CSI score was ≥ 3 for detection of nonbrain-dead patients, the CSI can detect 100% of cases with brain death from nonbrain-dead patients. Furthermore, if burst suppression (BS%) >75% is for detection of brain death and BS% between 0% and 75% is for detection of nonbrain-dead patients, the CSI could detect 100% brain-dead patients from nonbrain-dead patients.

Conclusion

MRI, CT and electroencephalography are time consuming and expensive, and require specialized people. In a previous study the Bispectral index scale (BIS) had been used for confirmation of brain death [3], but was not successful because the range of EEG filtration of BIS is wider than that of CSI and the calculation methods are different; moreover they did not consider BS% in addition to BIS. In the present study all of the clinically diagnosed brain-dead patients had CSI = 3 and BS% = 75%, and all of the clinically no-brain-death patients had CSI ≥ 3 and BS% ≤ 75. So the sensitivity and specificity of CSI for detection of brain death is 100%.