Patients eligible to participate in the study based on inclusion and exclusion criteria will be approached in the preoperative anesthesia clinic (at least one week before the scheduled operation) and some patients will be recruited on the day of surgery hours before in the waiting room by a study personnel who will not be involved in the patient care the day of the surgery. After addressing the patient's questions and concerns, informed consent will be obtained. The patient, the investigators and the anesthesiologist in charge of the patient will be blinded to group allocation until completion of the study.