Sédation en anesthésie : comment évaluer la profondeur ?

An increasing number of minimally invasive diagnostic and therapeutic procedures are susceptible to be performed under sedation, but the depth varies between light (anxiolysis) and deep (general anesthesia). Evaluation of the sedation's depth is of primary importance because it determines not only surgeons and patients' comfort, but also the incidence of related side effects. Clinical appraisal based on the MOAA/S (Modified Observer's Assessment of Alertness/Sedation) scale is the method most commonly used to discriminate between light/moderate and deep sedation levels (grade 2 = abolition of response to verbal stimulations). Monitoring of the cerebral electrical activity provides values correlated with the depth of sedation but is not reliable enough to significantly discriminate between light and deep sedation because of intra- and inter-individual variabilities. Monitoring of the plasmatic or alveolar concentrations of hypnotic agents could be a valuable indication only if a single drug is used.