Sedation is a state of depressed consciousness. There are depths or levels of sedation that range from minor to major depression of consciousness. Whereas depression of consciousness is a continuum, with no clear boundaries between levels, three levels of sedation have been defined and are in common use: minimal, moderate and deep sedation; they are recommended internationally1,6,44,196. The target level of sedation is the level that is intended for the patient. The level of sedation can vary according to the drug, the dose, the patient and the stimulus of the procedure. The level of sedation varies over time due to two main factors: the change in the concentration of the sedation drug within the patient and the variation in the stimulation that opposes sedation.