Plain English Summary
Background and study aims
Bispectral index (BIS) is a method used to monitor the depth of anesthesia. Administration of anesthetics in response to individual need as estimated BIS has been associated with reduced risk of awareness, reduced consumption of anesthetics, faster emergence from anesthesia and reduced incidence of postoperative nausea and vomiting. Although controversial, an impact on long-term mortality has been proposed. There are neuro-monitoring devices available but they are not used routinely, which shows that it is still not clear whether these technologies actually provide sufficient benefit to be cost effective. This aim of this study is to provide a carefully controlled global view on BIS monitoring during anesthesia that will be relevant to patients, anesthesia providers and the community.
Who can participate?
Patients 70 years or older undergoing major, elective, non-cardiac surgery.
What does the study involve?
BIS is recorded for all participants.
Then participants are randomly allocated to one of two groups: “open group” or “concealed group”,
BIS is available for guiding administration of anesthetics for participants in the “open group”. BIS data is recorded for subsequent analysis for participants in the "concealed" group.
A third group of age and gender matched people not undergoing surgery is recruited in order to correct cognitive testing results in the two study groups (for random variation over time and learning effect).
What are the possible benefits and risks of participating?
Participants allocated to the “open group” may benefit from more individualized administration of anaesthesics. Participants allocated to the “concealed” group will receive standard care.
Application of BIS electrodes is not associated with any risk. Risks with BIS monitoring have not been demonstrated.
Where is the study run from?
Länssjukhuset, Kalmar (Sweden)
When is the study starting and how long is it expected to run for?
From February 2004 to October 2010
Who is funding the study?
Medical Research Council of South East Sweden
Who is the main contact?
Dr Rolf Sandin
A prospective, randomized evaluation of utility of Bispectral index monitoring in elderly surgical patients
The hypothesis is that mean BIS values would be closer to a predefined target of 50 and significantly different from when no data from BIS monitoring is available, and that this anticipated difference in BIS between groups should be significantly related to improved outcome. Twenty-five outcome variables were allocated to one of three meaningful domains which constitute primary outcome. These domains are postoperative cognitive decline, perioperative cardiovascular compromise, and a socio-economic oriented domain.
We anticipate that potential benefits from individualized BIS guided anesthesia would be most obvious in the elderly population undergoing long procedures. Therefore we conduct this investigation in patients 70 years or older undergoing major, elective, non-cardiac surgery.
Regionala Etikprövningsnämnden i Linköping (IRB at Linköping University, Linköping, Sweden), 27/04/2005, reference number M25-5.
Single-center randomized controlled study
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use the contact details below to request a patient information sheet
Improved outcome after anesthesia by more precise administration of anesthetics in relation to individual need as assessed by bispectral index monitoring.
In study groups Bispectral index is recorded in all subjects but only available for guiding administration of anesthetics in the "open" group as opposed to the "concealed" group in which data is recorded for subsequent analysis.
Additional control patients not undergoing surgery were recruited to establish the learning effect and natural variation in performance over time in the cognitive testing for postoperative cognitive dysfunction.
Primary outcome measure
Postoperative cognitive dysfunction day 7 after surgery, global cardio-vascular outcome score (based on 10 subparameters), and global socio-economic outcome score ( based on 8 subparameters)
Secondary outcome measures
Intraoperative blood loss, net fluid and blood balance, urine production first 6 h postoperatively, postoperative hypoxemia (defined as SpO2 below 90%), increase in C-reactive protein postoperative day 3, weight gain postoperative day 3, awareness, 7 subparameters reflecting postoperative cognitive decline as described by Moller et al. (Lancet 1998; 351: 857-61), increase in Troponin-I 12-24 h after surgery, increase in Troponin-I 72 h after surgery, average intraoperative mean arterial blood pressure, duration of heart rate deviating >20% from baseline intraoperatively, duration of heart rate deviating >20% from baseline postoperatively, duration of systolic arterial blood pressure deviating >20% from baseline intraoperatively, duration of systolic arterial blood pressure deviating >20% from baseline postoperatively, duration of intraoperative inotropic support, number of patients given inotropic support postoperatively, duration of inotropic support postoperatively, age corrected average MAC-fraction of sevoflurane administered during anesthesia, duration of stay at the postoperative care unit, number of påatioents admitted to the ICU postoperatively, duration of sotal stay at the postoperative care unit and intensive care unit, length of hospital stay, number of patients being discharged to home, 30-day survival, 1-year survival.
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Aged over 70, both gender
2. Anticipated duration of surgery over 90 minutes
3. Being able to communicate in Swedish
4. No overt hearing or reading difficulties
Target number of participants
50 patients in each of the two study groups and 25 age matched control patients not undergoing surgery (control for cognitive testing).
Participant exclusion criteria
1. Unstable medical condition starting after inclusion but prior to surgery
2. Psychiatric disease
4. Lost to follow-up
5. Result from mini mental state examination <23
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Medical Research Council of South East Sweden - Forskningsrådet i Sydöstra Sverige (FORSS)
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
The results are intended to be published in a major scientific journal in the field of anesthesiology.
Intention to publish date
Participant level data
Available on request
Basic results (scientific)