Epileptiform EEG Patterns During Induction of General Anaesthesia With Sevoflurane Compared to Those With Propofol

Study Overview
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Brief Summary
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The aim of the study was to assess the influence of volatile induction of general anaesthesia with sevoflurane using two different techniques and intravenous anaesthesia with propofol on the possible presence of epileptiform electroencephalograph patterns during the induction of general anaesthesia. We aimed to verify whether presence of epileptiform patterns (EPs) defined as polispikes (PS), rhytmic polispikes (RPS), periodic epileptiform discharges (PED) on Electroencephalographs (EEGs) influence the behaviour of values of the Bispectral Index (BIS), State (SE) and Response (RE), A-line Auto Regressive Index (AAI) derived from middle latency auditory evoked potentials (MLAEP) during the induction of general anaesthesia using abovementioned techniques and such variations may be useful in detection of presence of EPs.

Detailed Description
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Both sevoflurane and propofol are considered safe and potent anaesthetics and are used for induction or coinduction of general anaesthesia. During all stages of general anaesthesia, both agents may induce seizure-like movements or seizures (clinically manifested events and confirming electroencephalographic pattern) accompanied by haemodynamic instability. Their proconvulsant activity should be verified and assessed. The aim of the additional analysis was to identify whether observance of the variations of values displayed on different depth of anaesthesia monitors (DOA monitors) reliably reflect the actual depth of general anaesthesia during presence of epileptiform patterns (EPs) in EEGs during VIGA with sevoflurane using two different techniques and intravenous induction of general anaesthesia with single dose of propofol. We performed standard 30-minute initial EEG recordings for all patients participating in the study to exclude any pre-existing epileptic EEG patterns. We took the initial EEG recordings in a dark quiet room for 5 minutes as a baseline, followed by three eye opening and closing sequences of 10 seconds each and photostimulation lasting 10 minutes (flash stimuli at frequencies of 3/6/9/12 Hz- alpha; 15/18/21/24 Hz- beta). Then we obtained another baseline reading and we asked the patients to achieve a state of hyperventilation by taking 20 forceful breathes per minute for five minutes. Finally, we obtained another baseline reading. Throughout the induction of anaesthesia and the surgery, standard monitoring procedures were utilised to pay close attention to the vital parameters such as non-invasive arterial pressure (BP), heart rate (HR), standard electrocardiography (ECG) II, arterial oxygen saturation (SaO2), fraction of inspired oxygen in the gas mixture (FiO2), facial electromyography (fEMG), fraction of inspired sevoflurane (FiAA), fraction of expired sevoflurane (FeAA), exhaled carbon dioxide concentration (etCO2), minimal alveolar concentration of sevoflurane (MAC).

Official Title
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Influence of Volatile Induction of General Anaesthesia With Sevoflurane Using Two Different Techniques and Intravenous Induction Using Propofol on the Epileptiform Electroencephalograph Patterns:

Conditions
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General Anaesthesia, Depth of Anaesthesia, Intraoperative Awareness, Seizures, Electroencephalography

Intervention / Treatment
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* Device: electroencephalography (EEG)
* Device: bispectral index (BIS)
* Device: response and state entropy (RE and SE)
* Device: middle latency auditory evoked potentials (MLAEP)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: an American Society of Anaesthesiologists (ASA) score I-II written informed consent to undergo general anaesthesia Exclusion Criteria: - history of epilepsy, medical treatment that might interfere with the EEG (e.g., tranquilizers, antiepileptic drugs), pregnancy, drug or alcohol abuse, history of neurological disease or a neurosurgical operation that would impair EEG or BIS monitoring, history of pulmonary disease, or the presence of signs predicting difficult mask ventilation or intubation. any pre-existing epileptic EEG patterns in standard 30-minute initial EEG recordings performed in all the patients participating in the study.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years


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: Diagnostic
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: sevoflurane - increasing concentrations<br>The patient was breathing spontaneously via the face mask and the sevoflurane concentration in the inhaled gas was doubled every 10 breaths starting from 0.3 vol. % in a sequence 0.3-0.6-1.2-2.4-4.8-8 vol. % until a minimal alveolar concentration (MAC) of 2 was obtained in the exhalation gas. Electroencephalography (EEG), bispectral index (BIS), response and state entropy (RE and SE), middle latency auditory evoked potentials (MLAEP) were monitored. | Device: electroencephalography (EEG)<br>* Four EEG channels were recorded using electrode positions as defined in the International 10-20 System with Ag/AgCl2 cup electrodes (Spes Medica) attached to the scalp with EC2 Electrode Cream (Grass Technologies). The impedance was set below 1 k, and the electrodes were attached to module S/5 E-EEG of the anaesthetic monitor S/5 (GE Healthcare).<br>Device: bispectral index (BIS)<br>* The BIS score was derived from a sensor (Aspect Medical Systems) positioned diagonally on the patients' foreheads according to producer's instructions.<br>Device: response and state entropy (RE and SE)<br>* The respone and state entropy (RE and SE) score was derived from a sensor (Aspect Medical Systems) positioned diagonally on the patients' foreheads according to producer's instructions.<br>Device: middle latency auditory evoked potentials (MLAEP)<br>* value of A-line Auto Regressive Index (AAI) derived from middle latency auditory evoked potentials (MLAEP) (A-line Monitor, Danmeter A/S, Odense, Denmark) was observed which measures the central nervous system responsiveness to a specific auditory stimulus<br>|
| Experimental: sevoflurane - vital capacity<br>The anaesthetic circuit was prefilled with 8% sevoflurane. The patients were asked to exhale to the residual volume. Then the patients were explained to perform a vital-capacity breath with a face mask applied tightly to their faces. Then the patients were encouraged to hold their breaths as long as possible. Thereafter, the patients were asked to breathe spontaneously. Electroencephalography (EEG), bispectral index (BIS), response and state entropy (RE and SE), middle latency auditory evoked potentials (MLAEP) were monitored. | Device: electroencephalography (EEG)<br>* Four EEG channels were recorded using electrode positions as defined in the International 10-20 System with Ag/AgCl2 cup electrodes (Spes Medica) attached to the scalp with EC2 Electrode Cream (Grass Technologies). The impedance was set below 1 k, and the electrodes were attached to module S/5 E-EEG of the anaesthetic monitor S/5 (GE Healthcare).<br>Device: bispectral index (BIS)<br>* The BIS score was derived from a sensor (Aspect Medical Systems) positioned diagonally on the patients' foreheads according to producer's instructions.<br>Device: response and state entropy (RE and SE)<br>* The respone and state entropy (RE and SE) score was derived from a sensor (Aspect Medical Systems) positioned diagonally on the patients' foreheads according to producer's instructions.<br>Device: middle latency auditory evoked potentials (MLAEP)<br>* value of A-line Auto Regressive Index (AAI) derived from middle latency auditory evoked potentials (MLAEP) (A-line Monitor, Danmeter A/S, Odense, Denmark) was observed which measures the central nervous system responsiveness to a specific auditory stimulus<br>|
| Experimental: propofol - intravenous induction<br>the patients were preoxygenated with 100% oxygen following which propofol was intravenously administered at a single dose of 2.5 mg/kg of body weight, after which it was infused with an infusion speed of 4 mg/kg body weight/h. Electroencephalography (EEG), bispectral index (BIS), response and state entropy (RE and SE), middle latency auditory evoked potentials (MLAEP) were monitored. | Device: electroencephalography (EEG)<br>* Four EEG channels were recorded using electrode positions as defined in the International 10-20 System with Ag/AgCl2 cup electrodes (Spes Medica) attached to the scalp with EC2 Electrode Cream (Grass Technologies). The impedance was set below 1 k, and the electrodes were attached to module S/5 E-EEG of the anaesthetic monitor S/5 (GE Healthcare).<br>Device: bispectral index (BIS)<br>* The BIS score was derived from a sensor (Aspect Medical Systems) positioned diagonally on the patients' foreheads according to producer's instructions.<br>Device: response and state entropy (RE and SE)<br>* The respone and state entropy (RE and SE) score was derived from a sensor (Aspect Medical Systems) positioned diagonally on the patients' foreheads according to producer's instructions.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| presence of epileptiform patterns in patients EEGs | the main objective is to measure the influence of volatile induction of general anaesthesia with sevoflurane using two different techniques and intravenous anaesthesia with propofol on the presence of epileptiform electroencephalograph patterns during the induction of general anaesthesia. | intraoperative | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| observance of BIS score behaviour during presence of epileptiform patterns in patients EEGs | the objective is to measure the BIS index variations during presence of EPs in patients' EEGs during volatile induction of general anaesthesia (VIGA) with sevoflurane using two different anaesthetic regimens compared to intravenous induction of general anaesthesia using single dose of propofol. | intraoperative | 
| observance of values of state and response entropy behaviour during presence of epileptiform patterns in patients | the objective is to measure values of state and response entropy index variations during presence of EPs in patients' EEGs during volatile induction of general anaesthesia (VIGA) with sevoflurane using two different anaesthetic regimens compared to intravenous induction of general anaesthesia using single dose of propofol. | intraoperative | 
| observance of values of middle latency auditory evoked potentials behaviour during presence of epileptiform patterns in patients | the objective is to measure values of middle latency auditory evoked potentials during presence of EPs in patients' EEGs during volatile induction of general anaesthesia (VIGA) with sevoflurane using two different anaesthetic regimens compared to intravenous induction of general anaesthesia using single dose of propofol. | intraoperative | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Epileptiform patterns, sevoflurane, propofol, bispectral index, state entropy, response entropy, A-line Auto Regressive Index, middle latency auditory evoked potentials