Out of funding, no differences between groups

A correlation between the bispectral index values and electroencephalographic patterns at the loss of consciousness (LOC) when using propofol in elderly patients, has not been determined.

Our aim is to describe the BIS values and the power of the alpha band in the electroencephalography in elderly patients, at the LOC moment.

Propofol is an anesthetic drug regularly used in elderly patients requiring anesthesia. The electroencephalographic pattern recognized when propofol is administered, is different to the pattern obtained in younger patients. Both groups presents an alpha and slow bands, but they differ in the intensity of the signal. Younger patients presents more intense electroencephalographic bands than older patients.

Bispectral index (BIS) is a clinical indicator used to evaluate the depth of anesthesia. A correlation between this indicator and the power of electroencephalographic bands has not been determined.

We will describe the LOC moment of elderly patients receiving propofol as anesthetic for general surgery, with the EEG characteristic bands and the BIS value obtained at that moment. The BIS values related to the EEG characteristic bands can be described, to correlate the actual indicators of depth of anesthesia with new parameters.

Inclusion Criteria:

• Patients over 65 years
• Scheduled for elective surgery requiring general anesthesia
• American Society of Anesthesiology (ASA) Score I or II

Exclusion Criteria:

• Patients with neurological diseases
• Requiring the use of two or more drugs affecting Central nervous system
• History of drugs or alcohol abuse
• Body mass index over 35 kg/m^2
• Propofol allergy
• Cardiac congestive failure
• History of coronary syndrome
• Minimental test altered (Score under 24 points)

Elderly patients scheduled for surgery are an understudied population. Incidence of postoperative delirium and other complications can be related to changes in cerebral dynamics under anesthesia, with effects observed even after the use of anesthetics agents.

To characterize changes in EEG patterns under the induction of anesthesia, can give new information to understand the physiology of the elderly brain under anesthesia.