Duration and Depth of Anesthesia Induced by a Bolus of Etomidate

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.

Inclusion criteria

• ASA I, ASA II, schedule for minor or moderate surgery.

Exclusion criteria

• Dependance to alcohol, to drugs, morphinique or psychotrop.
• Epilepsia of severe CNS impairement
• Body weight <70% or >130% to ideal body weight.