Objectives
Does intraoperative optimization of both depth of anesthesia and regional cerebral tissue oxygenation (rScO2) in elderly patients reduce postoperative cognitive decline (primary outcome) or delirium (secondary outcome)?
Design
Prospective randomized controlled single blind trial.
Setting
A single major urban teaching and university hospital and tertiary referral center.
Participants
Patients, 65 years of age and older, undergoing elective coronary artery bypass graft surgery on cardiopulmonary bypass.
Interventions
Intraoperative depth of anesthesia bispectral index (BIS) values were targeted at 50 ± 10. Regional cerebral tissue desaturations of more than 15% of the pre-induction value, or below 50%, were avoided.
Measurements and Main Results
Eighty-two patients were included, and mean depth of anesthesia values using BIS were significantly higher during surgery in the intervention group with 40.6 (7.3) versus 35.4 (6.7) in the control group, mean (standard deviation), p = 0.004. The cognitive function was similar between the treatment and control groups at 6 weeks postoperatively with a Mini Mental State Examination (MMSE) of 27 (26,29) in the intervention group and an MMSE of 29 (27,29) in the control group, median (interquartile range), with p = 0.12. The authors observed a reduction in the incidence of delirium, occurring in 2.4% (n = 1) of patients in the intervention group and in 20% (n = 8) in the control group (p = 0.01).
Conclusions
This pilot trial demonstrates that noninvasive target-controlled depth of anesthesia monitoring is feasible. Cognitive function at 6 weeks showed no difference between the treatment and control groups; however, postoperative delirium was reduced in the intervention group.