Bispectral Index (BIS) Values Required for an Adequate Depth of Anesthesia in Elderly Patients Using Propofol

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Bispectral Index (BIS) Values Required for an Adequate Depth of Anesthesia in Elderly Patients Using Propofol, According to the Characteristic Electroencephalographic Pattern

Conditions
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Anesthesia

Intervention / Treatment
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* Drug: Propofol


Participation Criteria
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Eligibility Criteria
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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)

Ages Eligible for Study
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Minimum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Elderly patients<br>Patients over 65 years, scheduled to general surgery, requiring general anesthesia | Drug: Propofol<br>* Induction of anesthesia using propofol, and recording the BIS values and EEG patterns during the induction<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| BIS values at which EEG patterns (Slow and alpha bands) appears in elderly population using propofol | To describe the BIS values correlated to specific EEG patterns | Induction of anesthesia | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Propofol concentration required to observe specific EEG patterns | To describe the serum propofol concentrations required for induction of anesthesia, to observe alpha and slow bands at the EEG. | Induction of anesthesia |