Comparison of Two Electroencephalograms (EEG) Monitors in Patients Undergoing General Anesthesia
Condition: Anesthesia; Deep Sedation
Study type: Interventional

Summary: 
      Hypothesis:

      There is a statistically measurable correlation between qNOX and rough clinical signs of
      insufficient anti-nociception such as movements during Laryngeal Mask Airway (LMA) insertion,
      skin Incision, LMA removal. It will reduce the problem of anticipating the nociception in
      patients undergoing general anesthesia.

      Objectives:

        1. to compare two indexes of hypnosis, the qCON (Quantium Medical, Spain) with the
           Bispectral index (BIS™) (Covidien, Boulder CO. USA), in patients undergoing surgery
           under sedation and general anesthesia.

        2. to assess the qNOX index of pain/nociception (Quantium Medical, Barcelona, Spain) and
           the qCON index of hypnosis.

        3. to assess qNOX reliability as a specific indicator of response to nociceptive
           stimulation.
    

Detailed description: 
      Monitoring the anti-nociceptive drug effect is useful because a sudden and strong nociceptive
      stimulus may result in untoward autonomic responses and muscular reflex movements. Unopposed
      stimulation may also 'overrule' a state of stable unconsciousness, with resultant awakening
      and awareness. The traditional clinical use of systolic or mean blood pressure is actually
      still one of the methods in everyday use for this monitoring purpose. Another cornerstone is
      the experience of which drugs and doses are effective in attenuating nociception. Alpiger and
      colleagues found that simple end-tidal monitoring of sevoflurane was a better predictor of
      nociceptive response than Auditory Evoked Potential.

      Thus, monitoring the state of anti-nociception with objective, non-clinical methods is still
      in a state of testing and development, without well-documented and proven methods for
      consistent 'no-fuss' clinical daily use. Some methods, like those using systolic blood
      pressure, are based on the reduced sympathetic response from the Central Nervous System (CNS)
      when in a state of drug-induced anti-nociception during concomitant surgical stress. These
      include the pulse plethysmogram amplitude, heart rate variability and/or amplitude,
      pupillometry, muscle tonus and skin conductance.They all have limitations in interpretation,
      as the state of sympathetic tone is strongly influenced by numerous factors, including
      hypovolemia, vasopressors, atropine and patient positioning. In addition, sympathetic tone is
      very unspecific in the awake or lightly sedated patient, as mood and subjective feelings have
      a strong impact.

      Attempts are also been made on using the EEG for monitoring of anti-nociception. This
      approach has been challenged as difficult, as most of the antinociceptive drugs effects are
      in the periphery, the medullary cord or deeper cerebral layers, far from the EEG signals
      derived from the frontal cortex. However, EEG is a 'mirror' of what is going on in other
      parts of the CNS and peripheral nervous system. One problem is to elucidate how the EEG
      signals may be used in a sensitive and specific way to reflect anti-nociception. Concepts
      such as response-entropy, Composite Variability Index and BIS variability score have been
      tested and launched.

      Quantium Medical has an EEG-based algorithm with two outputs: the qCON for unconsciousness
      and the qNOX for anti-nociception. This means that calculates and displays two indices. One,
      the qCON, is designed to provide information about the depth of the hypnotic state, similar
      to that provided by the BIS™ and Sedline™ monitor (Masimo, Irvine CA). The second index, the
      qNOX, is designed to provide information about the depth of the antinociceptive state. The
      qCON has shown a comparable performance with BIS, and qNOX has proved correlation with rough
      clinical signs of insufficient antinociception, such as movements during LMA insertion,
      laryngoscopy and tracheal intubation
    

Intervention name(s): qCON-qNOX; BIS
Intervention type(s): Device; Device
Intervention description(s): Each subject will have the qCON-qNOX monitor on his/her forehead + the BIS monitor; Each subject will have the BIS monitor on his/her forehead + the qCON-qNOX monitor
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Screening
Keywords: q-CON; q-NOX; BIS; Electroencephalograms (EEG); Laryngeal Mask Airway (LMA); Sedation; General Anesthesia