We propose to collect the data of vital signs and anesthesia medications administered in a subcategory of patients coming for anesthesia for upper GI endoscopy. This data will be analyzed to see any relation between the preoperative risk factors, procedure, type of anesthesia and the airway intervention. The adverse events that will be automatically recorded and later analyzed will be number of apnea episodes (described as no respiration for at least 30 seconds) duration of each apnea, number and duration of each desaturation event (oxygen saturation as measured by the pulse oximeter). A pulse oximeter saturation of less than 93 percent and lasting 30 seconds will be considered as a desaturation event. The airway interventions that will be recorded will be anything other than considered being routine. This includes LMA insertion, endotracheal intubation and the need to withdraw gastroscope to facilitate face mask ventilation. We also propose to monitor their awareness/depth of sedation/depth of anesthesia levels. This will be done using a monitor that analyses brain waves and gives an idea of sleep (anesthesia) depth. We can then see any correlation between any unwanted events and the sleep depth.