Condition category
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

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

Trial website

Contact information



Primary contact

MD, PhD Rolf Sandin


Contact details

Hospital administration

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

A prospective, randomized evaluation of utility of Bispectral index monitoring in elderly surgical patients


Study hypothesis

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.

Ethics approval

Regionala Etikprövningsnämnden i Linköping (IRB at Linköping University, Linköping, Sweden), 27/04/2005, reference number M25-5.

Study design

Single-center randomized controlled study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


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.

Intervention type



Drug names

Primary outcome measures

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


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

Participant type


Age group




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
3. Reoperation
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


Sponsor information


Medical Research Council of South East Sweden - Forskningsrådet i Sydöstra Sverige (FORSS)

Sponsor details

Forskningsrådet i Sydöstra Sverige

Sponsor type

Research council



Funder type

Research council

Funder name

Medical Research Council of South East Sweden - Forskningsrådet i Sydöstra Sverige (FORSS)

Alternative name(s)

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

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes