Duration and Depth of Anesthesia Induced by a Bolus of Etomidate
Condition: Anesthesia
Study type: Interventional

Summary: 
      Induction of general anesthesia requires to be safe and to ensure a proper level of
      anesthesia. A proper anesthesia is sufficient to guarantee loss of consciousness and amnesia
      and without being too depth leading to a electroencephalogram (EEG) with burst suppression.
      The depth of anesthesia is monitored by the bispectral index analyse of the EEG, this allows
      to detect any under- or over-dose of anesthesia. The monitoring works with an unknown
      algorithm (patent), which evaluate the state of consciousness in the patient.

      Etomidate and propofol are commonly use to ensure general anesthesia. Actually, really few
      litterature has objective informations about the monitoring of Etomidate. The few existant
      are the old ones and has just a clinical evaluation of the depth of anesthesia (loss of
      consciousness, loss of breathing, loss of palpebral reflex). Except the fact that these
      clinical evaluations come from the brain stem, and in fact are not reliable to assess the
      cortical activity which is reduced by etomidate.

      Therefore, some anesthetists are fearful that etomidate is not sufficient to ensure a proper
      anesthesia to intubate the patient.

      This interventionnal study has two purpose. Firstly, a survey will be conduct about the
      habits and beliefs when use of etomidate.

      Secondly, a prospective study will be conduct to monitore with the bispectral index the depth
      and duration of anesthesia with etomidate.
    

Detailed description: 
      Protocol with randomization in one of the 2 arms (0.2 vs. 0.3 mg / kg of etomidate), blind to
      the investigators.

      The right dosage will be prepared at the same time by a colleague anesthetist who will not
      participate in the study according to the randomization envelope that we will give to him
      earlier. To remain blind to this dosage, it will be diluted with physiological serum up to 30
      ml.

      These following procedures will be carried out in order:

      - Preparation by a colleague of the adequate dose of etomidate, reduced to 20 cc with
      physiological serum.

      No premedication with benzodiazepines (xanax).

        -  Standard monitoring (ECG + NIBP + SpO2)

        -  Monitoring the depth of anesthesia by bispectral analysis of the electroencephalography
           (BIS) trace

        -  Placement of a peripheral venous line (18 or 20 G) at the bend of the elbow (vein of
           good size to avoid potential discomfort during the injection of etomidate).

        -  Preoxygenation with a face mask

        -  Start remifentanil (20 μg / ml) in AIVOC mode with a site-effect concentration (Cet) of
           2 μg / ml) and wait for an equilibration.

        -  Injection of the induction dose of etomidate over 30 seconds.

        -  After loss of consciousness, curarisation with 0,6 mg/kg (rocuronium).

        -  Observation period of the depth of anesthesia. Ventilation support by light ventilation
           with a face mask.

        -  Special attention will be paid to avoid any interference with the BIS recording (do not
           move the patient to set it up, do not turn on the heating blanket).

      When the BIS rises above 60, the study stops. The anesthesia is then deepened by
      administration of propofol and is left to the discretion of the anesthesiologist in charge of
      the room.
    

Intervention name(s): induction by Etomidate bolus
Intervention type(s): Drug
Intervention description(s): General anesthesia induction by Etomidate bolus with different concentration in either of the two arms. First arm, has the concentration (0,2 mg/kg) commonly used of Etomidate to induce anesthesia. Second arm, has the concentration (0,3 mg/kg) usually proposed in medical literature.
Intervention MeSH terms: Etomidate
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Other