NEUROSCIENCES AND NEUROANAESTHESIA Bispectral and spectral entropy indices at propofol-induced loss of consciousness in young and elderly patients

Results. We analysed 35 elderly [average age, 78 yr (range, 67‐96)] and 34 young [35 (19‐40)] patients. At LOC, all indices were significantly higher in elderly compared with young patients: BISLOC, median 70 (range, 58‐91) vs 58 (40‐70); SELOC, 71 (31‐88) vs 55.5 (23‐79); and RELOC, 79 (35‐96) vs 59 (25‐80) (P,0.001 for all comparisons). With all three monitors, only a minority of elderly patients lost consciousness within a 40‐60 index range: two (5.7%) with BIS and RE each, and seven (20%) with SE. In young patients, the respective numbers were 20 (58.8%) for BIS, 13 (38.2%) for SE, and nine (26.5%) for RE. Conclusions. In adults undergoing propofol induction, BIS, SE, and RE indices at LOC are significantly affected by age. Br J Anaesth 2009; 103: 387‐93