The investigators believe that Propofol could be used in this instance. The arguments in favour of Propofol include its pharmaco-kinetic characteristics and the fact that it is currently used in other circumstances. Propofol has an action delay which is more rapid that Midazolam therefore its effect is seen 1 minute after a bolus and 5 minutes after for Midazolam. The effect after a short administration lasts only a few minutes however the effect of Midazolam is more prolonged (sometimes several hours). As with Midazolam, a titrated use in weaker doses, should allow sufficient sedation, in the context which interests us, without marked secondary effects.