The study will be prospective, randomized, controlled. Patients will be premedicated with diazepam, 0.1 mg/Kg and scopolamine, 0.05 mg/Kg, i.m. one hour prior to their arrival in the operatory theatre. Anesthesia will be induced by fentanyl, 0.1 mg, and propofol, 1.5-2 mg/Kg. After obtaining muscle relaxation with cis-atracurium, 0.15 mg/Kg, a Taper Guard Evac Murphy Eye Oral Tracheal Tube (Mallinkrodt, Mirandola, Italy) with an internal diameter of 9 in men and 8 in women, will be positioned. These tubes have a line for suctioning above the cuff. The cuff pressure will be set to 20-30 cmH2O and checked every 6 hours with a proper inflating device. Patients will be connected to a mechanical ventilator and anesthesia will be maintained with sevoflurane 1-2.5% and remifentanil, 0.05-0.15 mcg/Kg/min. At the end of surgery, patients will be moved to the cardiac surgical intensive care, connected to a mechanical ventilator, and sedated with propofol and remifentanil until the conditions needed for weaning from the ventilator (control of bleeding, cardiovascular stability, thermal equilibrium) are achieved. Then, propofol infusion will be stopped and remifentanil dosage decreased to 0.02-0.05 mcg/Kg/min. After a successful t-tube trial of spontaneous breathing, tracheal tubes will be removed. Remifentanil infusion will be continued and dosage titrated on patient pain evaluated with a VAS scale; paracetamol 1 g will be given if need be.