Burst Suppression, EEG With Abnormally Slow Frequencies, Postoperative Delirium
Conditions
Keywords
Intraoperative EEG based monitoring, Level of hypnosis, Burst suppression, Postoperative delirium, EEG-signal characteristics, Entropy
Brief summary
Burst suppression (BS) is a not physiological pattern in the electroencephalogram (EEG). BS during general anesthesia is mainly seen as a sign for too deep hypnosis and may increase the risk of postoperative delirium (POD), a disturbance of consciousness arising within 24 hours after surgery. This monocentric, simple masked randomized study aims primarily to investigate, whether particular anesthesiological interventions reduce the occurrence of intraoperative burst suppression. The investigator initiated trial includes 66 patients (male and female) aged ≥ 60 years in two groups (intervention and control group). Secondary aims will be the correlation of burst suppression and mean arterial pressure, concentration of anesthetics and postoperative delirium.
Detailed description
Intraoperative burst suppression represents a non physiological EEG pattern. According to the literature and scientific knowledge, intraoperative burst suppression patterns might be caused either by hypotension resulting in a reduced cerebral circulation or by an oversedation of anesthetics correlating with a very deep level of hypnosis. Some publications exist that discuss the occurrence of intraoperative burst suppression especially in elderly people (aged ≥ 60 years) as a predictor of postoperative delirium and postoperative cognitive dysfunction. None of the studies however was able to prove a causal relationship between burst suppression and postoperative delirium. Contrary it might simply be an epiphenomenon. Conducting this interventional trail primarily aims to prove whether specific anesthesiological interventions, such as the treatment of intraoperative hypotension in first line and/or the reduction of the concentration of anesthetics in second line, reduce intraoperative burst suppression. Hence it might be possible to investigate a possible casualty between burst suppression and postoperative delirium in a second trial.
Interventions
OTHERTreatment of hypotension and/or reduction of anesthetics
The treatment of hypotension can be done by the responsible anesthetist according to the clinical standard operations including any accepted drug typically used in this hospital. The reduction of anesthetics can be done either by reducing the volatile end tidal anesthetics concentration (ETAC) or the infusion rate of propofol.
Sponsors
Technical University of Munich
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
DOUBLE (Caregiver, Investigator)
Masking description
Single masked. The entropy and EEG module will be masked for the responsible anesthetist as well as the study team during the entire investigation.
Eligibility
Sex/Gender
ALL
Age
60 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Age ≥ 60 years * Surgical interventions in general anesthesia (volatile or total intravenous anesthesia) * expected surgery duration ≥ 1h * American Society of Anesthesiologists (ASA) 1-4 * written informed consent prior to study participation
Exclusion criteria
* Neurological or psychiatric disorders * hearing difficulty * deafness * neurosurgical (intra)cranial surgery * pregnancy * expected continuous mandatory ventilation after surgery
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Chance of the total, cumulative burst suppression rate. | During general anesthesia and within the intervention | The total, cumulative burst suppression rate (BSR) corresponds to area under the curve and is defined by the BSR (%) and the absolute duration of BSR (t). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Burst suppression rate during maintenance. | During maintenance within the intervention | Rate of change of the burst suppression ratio during maintenance. |
| Mean arterial blood pressure. | During burst suppression within general anesthesia | Evaluation of the mean arterial blood pressure with positive burst suppression rate. |
| Burst suppression rate during induction. | During induction within the intervention | Rate of change of the burst suppression rate during induction. |
| Specific characteristics of the EEG frequency spectrum during burst suppression | During burst suppression within general anesthesia | Evaluation of specific EEG frequencies differentiating BSR caused by hypotension or oversedation of anesthetics. |
| Postoperative delirium. | Within the first three postoperative days | Screening of the patients regarding a postoperative delirium by a brief confession assessment method (bCAM). |
| Endtidal anesthetic concentration (ETAC) and infusion rate of propofol. | During burst suppression within the intervention | Evaluation of the mean ETAC and infusion rate of propofol. |
Countries
Germany
Outcome results
None listed