An exploratory study of the bilateral bispectral index for pain detection in traumatic-brain-injured patients with altered level of consciousness.

INTRODUCTION: Many patients with a traumatic brain injury (TBI) cannot communicate because of altered level of consciousness. Although observation of pain behaviors (e.g., frowning) is recommended for pain assessment in nonverbal populations, they are attenuated and sometimes even suppressed in patients with TBI receiving high doses of sedatives. This study explored the potential utility of the bilateral bispectral index system (BIS) for pain detection in critically ill adults with TBI and altered level of consciousness.

METHODS: Using a repeated measure within-subject design, participants (N = 25) were observed for 1 minute before (baseline), during, and 15 minutes after two procedures: (a) noninvasive blood pressure (nonnociceptive) and (b) turning (nociceptive). At each assessment, BIS indexes (0-100) of the right (R) and left (L) hemispheres and pain behaviors were documented.

RESULTS: Compared with baseline, significant median increases (p ≤ .05) in BIS-R (+4.93%) and BIS-L (+8.43%) and in the frequency of pain behaviors (+3.00) were observed during turning but not noninvasive blood pressure. Interestingly, increases in BIS-R were more pronounced in participants with left-sided TBI (+17.23%, p = .021) than those with right-sided TBI (+3.01%). BIS-R fluctuations in participants with left-sided TBI were also positively correlated (r(s) = .986, p ≤ .001) with the frequency of pain behaviors observed during turning.

CONCLUSIONS: Overall, only increases in BIS-R were correlated with participants' pain behaviors and in those with left-sided TBI exclusively. Although further research is needed, our findings support the potential use of the bilateral BIS for pain detection in nonverbal patients with TBI who cannot behaviorally respond to pain, but only when they have a left-sided injury.