Epileptiform EEG Patterns During Induction of General Anaesthesia With Sevoflurane Compared to Those With Propofol
Condition: General Anaesthesia; Depth of Anaesthesia; Intraoperative Awareness; Seizures; Electroencephalography
MeSH terms: Seizures; Intraoperative Awareness
Study type: Interventional

Summary: 
      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: 
      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).
    

Intervention name(s): electroencephalography (EEG); bispectral index (BIS); response and state entropy (RE and SE); middle latency auditory evoked potentials (MLAEP)
Intervention type(s): Device; Device; Device; Device
Intervention description(s): 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).; The BIS score was derived from a sensor (Aspect Medical Systems) positioned diagonally on the patients' foreheads according to producer's instructions.; 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.; 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
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Diagnostic
Keywords: Epileptiform patterns; sevoflurane; propofol; bispectral index; state entropy; response entropy; A-line Auto Regressive Index; middle latency auditory evoked potentials