A study to find out which oxygen mask works better after general anesthesia to improve oxygen levels. Hudson mask vs Venturi mask

INTERVENTION: Intervention1: VENTURI MASK: Venturi mask applied immediately after extubation. FiO2 set to 0.40 red coded adaptor at the recommended flow rate that is 10 to 12 liter per minute till the patient is observed in PACU Control Intervention1: HUDSON MASK: Hudson mask applied immediately after extubation. Oxygen flow rate 8 liter per minute till the patient is obsereved in PACU. CONDITION: Health Condition 1: K800‐ Calculus of gallbladder with acutecholecystitis PRIMARY OUTCOME: Incidence and rate of hypoxic episode Spo2 less than 94 percent with in the first post operative hourTimepoint: 2 years SECONDARY OUTCOME: Mask comfort as reported by the patient Likert scale ; Time to first documented desaturation episode Spo2 less then 94 percentTimepoint: 2 years INCLUSION CRITERIA: Age 18 to 60 years ASA physical status I to II Patients extuabted after elective surgery under general anaesthesia Hemodynamically stable patients