The maximum value of bispectral index predicts outcome in hypoxic-ischemic encephalopathy after resuscitation, better than minimum or mean value

ABSTRACT

Objective: Although bispectral index (BIS) has been widely used for predicting neurological outcomes in clinical practice, its optimal value concerning maximum (BIS_max), minimum (BIS_min) and mean (BIS_mean) on accurately predicting the prognosis of patients with hypoxic-ischemic encephalopathy (HIE) after resuscitation has not been clearly determined.

Methods: For a total number of 45 cases, the duration of each BIS measurement was 12 h, with the data collected at a 30 min interval. Outcome was recorded as survival and non-survival count 60 days after the resuscitation. Receiver operator characteristic curve was used to assess the BIS_max, BIS_min and BIS_mean for predicting clinical outcome.

Results: By the end of observation, 20 cases (44.4%) survived with a significantly higher BIS_max. The area under the curve for BIS_max of predicting survival was the highest compared to BIS_min and BIS_mean. The optimal cut-off value of BIS_max was 71.5 with 100% sensitivity and 60% specificity. Ten patients presented BIS value down to zero at any time point did not survive the observation.

Conclusion: The BIS_max is a better outcome predictor than BIS_min or BIS_mean for patients with HIE after resuscitation. Lower BIS_max represents higher risk of mortality. Additionally, BIS value decreases to zero represents a poor outcome.

KEYWORDS:

• Bispectral index
• resuscitation
• hypoxic-ischemic encephalopathy
• brain injury

Acknowledgments

We would like to thank the staff of the Intensive Care Unit at No. 401 Hospital of the Chinese Peoples’ Liberation Army for their help and support in the conduct of this work, as well as their excellent care of patients resuscitated from cardiac arrest. We are grateful to Mengchun Gong, (Peking Union Medical College Hospital, Beijing, China) for critical review of this manuscript.

Declaration of interest

None of the author has received any kind of compensation or support from the manufacturers of BIS equipment. The authors alone are responsible for the content and writing of the paper.