Brain Oscillatory Signatures of Auditory Stimuli Across Different Vigilance and Sedation States

Study Overview
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Brief Summary
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The investigators want to explore how presenting acoustic stimuli influences brain oscillatory signatures and heart rhythm- dynamics across different vigilance and sedation states. The investigators will administer acoustic stimuli during sedation and anaesthesia while brain activity and heart activity are being recorded by electroencephalogram and electrocardiogram. On the day following anaesthesia an optional nap/sleep period's EEG and ECG will be recorded. During this short sleep, patients will again be exposed to acoustic stimuli. The recorded EEG and ECG will be compared intra-and inter-individually to recordings from sedation and anaesthesia.

Official Title
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Brain Oscillatory Signatures of Auditory Stimuli Across Different Vigilance and Sedation States

Conditions
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Anesthesia, Sleep

Intervention / Treatment
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* Other: Acoustic stimuli


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Informed Consent as documented by signature Good general health status Planned ophthalmic/plastic surgery at Inselspital Berne Exclusion Criteria: Contraindications on ethical grounds Neurological/neurodegenerative disorder Hearing problems (only if patients are not able to perceive the acoustic stimuli) Pacemaker Deep brain stimulator Pregnancy Known or suspected drug or alcohol abuse Critical surgery procedure

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 84 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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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Interventional Model Description: The investigators forecast a maximal enrollment of 80 participants. However, an interim-analysis will be conducted after 10-14 participants to check estimated effect-size of intervention.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Acoustic stimuli<br>Acoustic stimuli and comparison to within-subject baseline | Other: Acoustic stimuli<br>* During different states of sedation/anaesthesia and sleep, acoustic stimuli will be presented and compared to a within-subject baseline.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Brain oscillatory power derived by EEG | Brain oscillatory response to acoustic stimuli derived by power spectral density in canonical frequency bands from 0.5 up to 40 Hz. | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Brain oscillatory response derived by Hilbert Amplitude | Brain oscillatory response to acoustic stimuli derived by Hilbert-transforming EEG data and extracting Hilbert amplitude in microVolts | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Spindle characteristics - number of spindles | Number of spindles | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Spindle characteristics - amplitude of spindles | Spindle amplitude in microVolts | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Spindle characteristics - frequency of spindles | Frequency of spindles in Hz | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Spindle characteristics - duration of spindles | Duration of spindles in ms | Continuously across anaesthesia/sedation/sleep up to 8 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Heart rate | Heart rate derived from echocardiogram in bpm | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Instantaneous heart rate | Instantaneous heart rate derived from echocardiogram in bpm | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Heart rate variability | Heart rate variability derived from echocardiogram in ms | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Slow wave characteristics - amplitude | Slow wave amplitude in microVolt | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Slow wave characteristics - number | Number of slow waves | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Slow wave characteristics - frequency | Frequency of slow waves in Hz | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Slow wave characteristics - slope | Slope of slow waves in microVolts/s | Continuously across anaesthesia/sedation/sleep up to 8 hours | 
| Number of sleep arousals |  | Continuously across sleep up to 8 hours |