Rationale: There is evidence, both investigational and anecdotal, that airway changes may occur during certain surgeries or procedures, and that patient positioning may play a large role in precipitating them. However, research on this phenomenon in the surgical population, unlike the obstetric population, is sparse. Similarly, investigations into the time required for airway changes to regress back to baseline has been included in a number of obstetric airway studies, but not in any surgical ones. Lastly, it has been suggested that other surgical factors, such as fluid balance or procedure duration, may alter the degree of airway changes, but results from the few recent studies on the topic have been unclear. Thus, this study seeks to further investigate the influence of prone and Trendelenburg positioning, as well as surgical variables, on perioperative airway changes, and quantify the time required for patients' airways to return to their preoperative state.