Bispectral Index monitoring in cancer patients undergoing palliative sedation: a preliminary report.

INTRODUCTION: Continuous palliative sedation (PS) is currently titrated based on clinical observation; however, it is often unclear if patients are still aware of their suffering. The aim of this prospective study is to characterize the level of consciousness in patients undergoing PS using Bispectral Index (BIS) monitoring. PATIENTS AND METHODS: We enrolled consecutive patients with refractory symptoms requiring PS. We documented the level of sedation using Ramsay Sedation Scale (RSS) and BIS at 0, 2, 4, 6, 12, and 24 h during the first day of PS and examined their degree of association. Intravenous midazolam or propofol was titrated according to the sedation level.
RESULTS: Twenty patients on PS were recruited and had BIS continuous monitoring. Delirium was the most frequent reason for PS (n = 15, 75%). The median time of sedation was 24.5 h (interquartile range 6-46). The average time to achieve the desired sedation level was 6 h, and dose titration was required in 80% of the cases. At baseline, 14 (70%) patients were considered to be awake according to RSS (i.e., 1-3) and 19 (95%) were awake according to BIS (i.e., >60%). This proportion decreased to 31 and 56% at 4 h, 27% and 53 at 6 h, and 22 and 33% at 24 h. RS and BIS had moderate correlation (rho = -0.58 to -0.65); however, a small proportion of patients were found to be awake by BIS (i.e., ≥60%) despite clinical observation (i.e., RSS 4-6) indicating otherwise.
CONCLUSIONS: The BIS is a noninvasive, bedside, real-time continuous monitoring method that may facilitate the objective assessment of level of consciousness and dose titration in patients undergoing PS.