Our hypothesis is that the tracheal tubes with a polyurethane and/or a conic shaped cuff are associated with a lower colonization of the tracheal tree during the days following tracheal intubation, than tubes with a cylindrical polyvinyl chloride cuff. The patients will be allocated to randomized clusters into four groups : 1) cylindrical PVC cuff, 2) cylindrical polyurethane cuff, 3) conic PVC cuff and 4) conic polyurethane cuff. In the four groups, the tubes will be inserted with the conventional technique of tracheal intubation under general anesthesia and direct laryngoscopy, inside the ICU. The tube cuff will be immediately inflated to a 25 cm of water or at the plateau pressure level of the ventilator in case it is higher than 25 cm of water according to the current recommendations. The tracheal tube will be connected to the ventilator, set in a volume or pressure control mode with a minimal PEEP of 5 cm of water.