Comparison of the Classic Face Mask Versus NuMask for Preoxygenation

The administration of oxygen before anesthetic induction and tracheal intubation (preoxygenation) is a well-recognized technique designed to increase oxygen reserves and thereby delay the onset of arterial oxygen desaturation during apnea. It is particularly important if manual ventilation is not desirable prior to intubation (eg: rapid sequence induction) or if difficulty with ventilation or intubation is anticipated or in patients with oxygen transport limitations. Because the "cannot ventilate/cannot intubate" situation is an unpredictable event, theoretically all patients should be maximally preoxygenated. Fraction of inspired oxygen (FIO2) is one of the factors in achieving maximal preoxygenation. A common reason for the failure to achieve an FIO2 close to 1.0 is a leak under the face mask. Several factors may contribute to the leak. These are edentulous patients, patients with sunken cheeks, bearded patients, the presence of nasogastric tubes, wrong size face masks, improper use of head straps, and patients with large heads and faces where even the large size mask may not fit properly. Recently a new intraoral mask "NuMask" has become available for anesthetic induction. It is placed under the lips and outside the gums of the patient mouth (similar to snorkel mouth piece), thus providing a good seal in almost any patient. In addition to providing a good seal, the NuMask has other advantages over the standard face mask. It has very small dead space (18 cc : 110 cc), provides comfortable grip, ventilation can be provided from any position and causes less facial trauma. The efficacy of preoxygenation using the NuMask will be compared to the classic face mask in approximately 30 healthy and consenting adult volunteers. All of the volunteers will be randomly assigned into one of 2 groups. All volunteers will be tested for three (3) periods of 5 minute intervals. Inspired oxygen (FIO2), end-tidal oxygen (ETO2), end-tidal carbon dioxide (ETCO2) and respiratory rate (RR) will be tested. Analysis of the data may reveal whether the NuMask is equal, superior, or inferior to the classic face mask in achieving maximal preoxygenation. Although the NuMask has been tested and used in various scenarios of airway management, its efficacy in achieving maximal preoxygenation has not been studied