Sedative Premedication: Efficacy On Patient Experience

Seven French university hospitals will participate in this multicentric prospective, blinded and randomized study. The investigators designed 3 study groups: Lorazepam 2.5mg, Placebo (microcrystalline celluloses) and no premedication at all. The third group (no premedication) is necessary in order to evaluate a placebo response, which may be significant on anxiety level and patients perceptions of care. It was calculated that 969 patients had to be included in order to obtain a 5 point difference between groups on the EVAN score with 80 % statistical power, leading to the inclusion of 1200 patients with an estimated maximum dropout rate of 15 %. All adults below 70 years and scheduled for elective surgery under general anesthesia can be included after information by an anesthesiologist in charge of the study and written informed consent. Non inclusion criterions are: a weight below 45 Kg, a counter indication to benzodiazepine, surgeries that could impair cognitive functions (cardiac or neurologic surgery), usual use of neuroleptics or lithium, drug addiction or former cognitive disease. The technique of anesthesia will be decided by the attending anesthesiologist, who will be unaware of the premedication technique, independently of the study protocol.