Patients taken to the operating room were monitored for heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), electrocardiography (ECG-Derivation II), and peripheral oxygen saturation (SpO2) before anesthesia induction. Depth of anesthesia was evaluated with a bispectral index monitor. The patients were preoxygenated with 6 L.min-1 oxygen through a face mask for 3 minutes. For anesthesia induction 0.02 mg.kg-1 midazolam, 1-2 μg.kg-1 fentanyl and 1-2 mg.kg-1 propofol were used. Afterwards patients were given mask ventilation with 100% oxygen. Before laryngeal masks were inserted they were prepared by being lubricated with water-based gel and the cuffs were completely deflated.