Application of Tsallis Entropy to EEG: Quantifying the Presence of Burst Suppression After Asphyxial Cardiac Arrest in Rats

• Published in: IEEE transactions on biomedical engineering 2010-04, Vol.57 (4), p.867-874
• Main Authors: Zhang, Dandan, Jia, Xiaofeng, Ding, Haiyan, Ye, Datian, Thakor, Nitish V.
• Format: Article
• Language: English
• Subjects: Algorithms; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Area measurement; Asphyxia; Biological and medical sciences; Brain damage; Brain injuries; Brain modeling; Burst suppression (BS); Cardiac arrest; cardiac arrest (CA); EEG; Electrodiagnosis. Electric activity recording; Electroencephalography; Electroencephalography - methods; Emergency and intensive cardiocirculatory care. Cardiogenic shock. Coronary intensive care; Entropy; Heart Arrest - complications; Heart Arrest - physiopathology; Hypoxia, Brain - complications; Hypoxia, Brain - physiopathology; Intensive care medicine; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Nervous system; quantitative; Rats; Rats, Wistar; Reproducibility of Results; Rodents; Signal Processing, Computer-Assisted; Studies; Testing; Tsallis entropy (TsEn)
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2009.2029082

Burst suppression (BS) activity in EEG is clinically accepted as a marker of brain dysfunction or injury. Experimental studies in a rodent model of brain injury following asphyxial cardiac arrest (CA) show evidence of BS soon after resuscitation, appearing as a transitional recovery pattern between isoelectricity and continuous EEG. The EEG trends in such experiments suggest varying levels of uncertainty or randomness in the signals. To quantify the EEG data, Shannon entropy and Tsallis entropy (TsEn) are examined. More specifically, an entropy-based measure named TsEn area (TsEnA) is proposed to reveal the presence and the extent of development of BS following brain injury. The methodology of TsEnA and the selection of its parameter are elucidated in detail. To test the validity of this measure, 15 rats were subjected to 7 or 9 min of asphyxial CA. EEG recordings immediately after resuscitation from CA were investigated and characterized by TsEnA. The results show that TsEnA correlates well with the outcome assessed by evaluating the rodents after the experiments using a well-established neurological deficit score (Pearson correlation = 0.86, p ¿ 0.01 ). This research shows that TsEnA reliably quantifies the complex dynamics in BS EEG, and may be useful as an experimental or clinical tool for objective estimation of the gravity of brain damage after CA.