In the operating room, routine monitors were attached to the patients and turned on. After pre-oxygenation with 100% O2 by face mask using eight breaths vital capacity method, anaesthesia was induced with injection fentanyl 1-2 mcg/kg, propofol 2-3 mg/kg and rocuronium 0.6-0.9 mg/kg. Lungs were ventilated taking care not to inflate the stomach. Maintaining cricoid pressure trachea was intubated with cuffed endotracheal tube. Placement and position was confirmed with EtCO2 monitor and then secured properly. After establishing stable anaesthesia, an endotracheal tube sized 8.5 internal diameter was passed via oral route in the esophagus with anterior displacement of larynx. A predetermined length marked with adhesive tape (xiphoid process to ear lobule- fro ear lobule to nasal tip) of stomach tube sized 18 F was passed through the esophageally placed endotracheal tube. Placement of this tube within the stomach was verified with auscultation over the epigastrium during insufflation of 10-15 ml of air. Gastric contents were gently aspirated manually with 60 ml syringe by an investigator who was blind of group assignment. Applying manual pressure over the epigastrium while the patient was in supine and then left and right lateral positions, gastric tube was then manipulated to ensure maximum emptying of gastric contents. The stomach tube was then removed followed by esophageally placed endotracheal tube. Any problem encountered during inserting or removing the oro-esophageally placed endotracheal tube or gastric tube was also recorded. The volume of gastric contents was measured with graduated syringe and pH using pH meter. The pH meter was calibrated using standard buffers at pH values of 4, 7 and 9.20. This pH meter has a precision of 0.01 units over the entire pH range. A minimum of one-millimeter volume of gastric contents was sufficient for pH determination with pH meter. In case of very little amount of gastric contents, we cut the stomach tube and aspirated gastric material with disposable plastic pipette. Samples less than one-millimeter were considered as no gastric contents because a minimum of one- millimeter of gastric contents was sufficient for pH- metry. Using bile salts as marker for bile, we applied qualitative Hay's sulphur test for the presence of bile salts. A minimum volume of one millimeter of gastric contents was adequate to perform Hay's sulphur test. In this test finely powered sulphur is sprinkled on the surface of cool (17 OC or below) liquid. If bile salts are present sulphur sinks down, sooner or later, in accordance with their percentage. If bile salts are present in from 1:5,000 (0.02%or 200 mcg/ml to 1:10,000 (0.01% or 100 mcg/ml) sulphur at once begins to sink and all precipitated in two or three minutes; even in dilution of 1:120,000 (0.0008% or 8.33 mcg/ml precipitation occurs. On the other hand, if sulphur remains floating on the surface, bile salts are absent.