The anaesthesia pre-oxygenation trial - using O2 Flush and Nasal oxygen for pre-oxygenation compared to traditional methods.

Prior to general anaesthesia the standard of care is to pre-oxygenation all patients. This involves the patient breathing 100% oxygen via a face mask. The 3 most common methods of pre oxygenation involve 4 deep breaths over 30 seconds, 8 deep breaths over 60 seconds or 3 minutes of tidal volume breathing (normal breathing) using high flow 100% oxygen (15L per minute via the anaesthesia machine with a face mask). The most common reasons for poor preoxygenation is an inadequate face mask seal resulting in the patient breathing room air (low oxygen content) through the leak. Nasal oxygen and the anaesthesia machine oxygen flush delivery higher flow rates than the standard method by the the anaesthesia machine so may reduce the amount of inspired air from the leak. Study Hypothesis - High flow oxygen with nasal oxygen or anaesthesia machine oxygen flush produces higher end tidal oxygen levels (better pre oxygenation) in the simulated mask leak scenario.