Bilateral Bispectral Index, Asymmetries and Post-operative Delirium

IRCCS Azienda Ospedaliero-Universitaria di Bologna84 enrolled

Overview

The primary objective of the study is to describe the value of interhemispheric asymmetry (ASYM), during the different intra- and peri-operative phases, in those patients who develop or do not develop post-operative delirium (POD) during the first 30 post-operative days and postoperative cognitive disfunction (POCD) in the first 90 post-operative days, in a population undergoing head\&neck and plastic surgery with a priori increased probability of POD.

Values of the study variables will be extract in these specific moments (considering a delay of thirty seconds between the in vivo phenomenon and the instrument): (t1) BIS probe application (t2) 60" before GA administration (t3) 60" after myoresolution (t4) intubation (t5) surgical incision (t6) end of ipnosis (t7) 10 minutes after extubation. Daily follow-up for the first five post-operative days is performed in order to verify the onset of POD and a telephone follow-up at thirty and ninety post-operative days in order to verify the onset of POD / POCD. CAM scale will be used for the diagnosis of POD; while for the diagnosis of POCD, 6-CIT test will be used, the EQ50 test in the case of tracheostomized patients.

Study Type

OBSERVATIONAL

Enrollment

Conditions

Postoperative Delirium Postoperative Cognitive Dysfunction

Interventions

In patients undergoing surgery and general anesthesia, the investigators want to examine -using bilateral BIS monitor- synthetic electroencephalographic differences between the two cerebral hemispheres (ASYM) to evaluate any correlation with the development of POD and POCD in the post-operative period.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 90 Years

Medical Language ↔ Plain English

Inclusion Criteria: -Patients, undergoing head\&neck surgery, who have at least 3 of the following criteria (to establish "a priori" increased risk of POD): * Age\> 70; * Male sex; or ASA III; * Smoker; * High blood pressure; Exclusion Criteria: * ASA IV, V or ASA IE, IIE, IIIE (patients with anesthetic risk ASA\>III and those undergoing urgent-emergency surgery will be excluded from the study); * Past positive medical history for: * Stroke; * Dementia; * Cerebral aneurysm; * Intracranial mass; * Head trauma; * Epilepsy; * Diabetes mellitus; * Previous neurosurgical intervention; * Psychiatric illnesses requiring chronic treatment; * Patients undergoing surgery in the previous two weeks; * Patients whose hospitalization duration is estimated to be less than five days; * Lack of understanding of the Italian language or English; * Age \<18 years.

Outcomes

Primary Outcomes

Correlation between ASYM (EEG-derived cerebral hemispheric asymmetries) at specific intraoperative timepoints and development of Postoperative Delirium (POD) or Postoperative Cognitive Dysfunction (POCD)

Primary aim of the study is to describe values of ASYM, during different intraoperative phases, in patients who develop -or do not- POD within 5 postoperative days and POCD at 30 and 90 postoperative days. Bilateral BIS monitor records values of right and left BIS scores (dimensionless number EEG-derived from 0 to 100), therefore, the asymmetry between the two (ASYM) evaluated as the total power difference for the frequencies between 0 and 30 Hz between right and left hemisphere \[Formula 1\]. An asymmetry of 50% indicates the same power in both hemispheres; while an ASYM lower than 50% indicates a lower power in the left hemisphere than in the right. Formula 1: ASYM= total power left/(total power left+total power right) x 100 Dispersion of ASYM will be expressed as the mean right to left difference ±2 standard deviation.The statistical difference of the model will be evaluated with the use of ANOVA tests.

Time frame: between 30 and 90 postoperative days

Secondary Outcomes

Incidence of Postoperative Delirium (POD) and Postoperative Cognitive Dysfunction (POCD) in head&neck and plastic surgery

Secondary outcome of the study is to describe the incidence of Postoperative Delirium (POD) and Postoperative Cognitive Dysfunction (POCD) in patients undergoing head\&neck and plastic surgery considered at "priori" high risk for development of POD with CAM scale and CIT-6 scale

Time frame: follow-up at 5, 30 and 90 postoperative days

Correlation between values of bilateral BSR, bilateral sBIS, bilateral sEMG at specific intraoperative timepoints and development of POD or POCD

Secondary outcome is to evaluate differences in BIS monitor derived values: bilateral bilateral burst suppression ratio (BSR), bilateral bispectral index (BIS), bilateral elecromyography (sEMG), during the different intraoperative phases (repeated measures), between the group of patients who develop at least one episode of POD within 5 days and the group of patients who develop at least one episode of POCD within 90 postoperative days. Mean Differences ±2 standard deviation of these values will be evaluated in relation to the primary outcome (DPO and DCPO) through the use of a linear mixed effects model based on both inter-patient and inter-evaluation variability. The statistical difference of the model will be evaluated with the use of ANOVA tests.

Time frame: Intraoperative phase: (t1) BIS probe application (t2) 60 seconds before GA administration (t3) 60 seconds after myoresolution (t4) intubation (t5) surgical incision (t6) end of ipnosis (t7) 10 minutes after extubation

Secondar outcomes is to evaluate inter and intra-patient variability of EEG-derived values at specific intraoperative timepoints

Describe the inter- and intra-patient variability of the electroencephalographic derived values, during different intraoperative phases of general anesthesia. Differences in ASYM, bilateral BSR, bilateral sBIS, bilateral sEMG values during different peri-operative stages will be described (exploratory outcome)