The most challenging aspects of laryngeal and laryngotracheal procedures are difficulty of exposure and airway management. These procedures require use of microlaryngeal instruments through a small lumen of a rigid laryngoscope, and are oftentimes difficult to perform with a standard endotracheal tube in place. Similarly, when performing endoscopic evaluation of the trachea, access to the space and visualization of the entire 360-degree view of the trachea is crucial.~To overcome these challenges, a number of techniques for oxygen delivery have evolved over time. Among them are use of a small endotracheal tube, use of jet ventilation and intermittent apnea with periodic removal of the endotracheal tube. The aforementioned methods of airway management carry inherent risks of airway injury, can be accompanied by brief periods of hypoxia or hypercarbia, and can sometimes lead to tenuous airway management scenarios for both the surgeon and the anesthesiologist when clear communication and familiarity with the airway management plan during the procedure are sub-optimal. For this reason, there is an ongoing search for acceptable solutions to minimize these risks during upper airway surgery.~One of the newly emerging advanced oxygenation techniques, also known as Hi-VNI (High Velocity Nasal Insufflation), allows for delivery of humidified oxygen through a specialized high-flow nasal cannula at rates of up to 40 l/min. This non-invasive high flow respiratory support system is currently being used in the treatment of respiratory failure in both adult and pediatric patients. This technique provides sustained oxygenation due to reduction in airway resistance, a build-up of airway pressure with oxygen-rich gas and active gas exchange, which lead to flushing of anatomic dead space, and delivery of oxygen into the lungs. This oxygenation technique can be used both in spontaneously breathing patients and under apneic conditions, while providing an unobstructed surgical view with the glottis, subglottis and trachea fully accessible for instrumentation.~The goal of this study is to establish the efficacy of Hi-VNI in upper airway surgery, to document the advantages and disadvantages of this technique from the standpoint of the airway surgeon and the anesthesiologist, and to provide more information about the optimal patient and airway pathology as well as suitable clinical scenarios when Hi-VNI device can be used for oxygenation during upper airway surgery. The researchers hypothesize that in appropriate clinical situations, Hi-VNI can ease airway management, shorten case duration, and provide superior operating conditions including space for instrumentation during upper aerodigestive tract procedures.
The goals of this study are to establish the efficacy of Hi-VNI (High Velocity Nasal Insufflation) in upper airway surgery from the anesthesiologist's and surgeon's perspectives, and to describe the ideal patient and the ideal pathology as well as suitable clinical scenarios when this oxygenation technique should be selected.