Real Time Assessment of Pre-oxygenation Utilizing End-tidal Oxygen Measurements Versus Single Breath End-Tidal Oxygen Measurements in Healthy Volunteers

Patients in the Emergency Department (ED) undergoing Rapid Sequence Intubation (RSI) are at risk for serious morbidity and mortality. In order to provide oxygen during the apneic period, it is common practice to provide pre-oxygenation prior to the start of the procedure with high flows of oxygen. Techniques commonly employed to pre-oxygenate ED patients undergoing RSI include high flow oxygen via a non-rebreather mask (NRBM), a self-inflating bag-valve mask (BVM), or non-invasive ventilation (NIV). However, there are currently no studies that explore how to assess the quality of a patient's pre-oxygenation in real time prior to intubation. Several recent studies that have assessed the use of single breath end-tidal oxygen to assess the effectiveness of various oxygenation strategies. Typically, healthy volunteers are placed on 2 to 3 minutes of a certain pre-oxygenation strategy followed by exhalation of a single breath into an end-tidal oxygen sensor. Higher end-tidal oxygen measurements are used as a marker for pre-oxygenation with higher percentages indicating more complete pre-oxygenation. A goal EtO2 reading of 90% is typically used to indicate maximal pre-oxygenation. However, this method of assessing pre-oxygenation would be impractical in actual ED patients who are critically ill and may not be able to fully participate in such a measurement. In addition, discontinuing a pre-oxygenation method to obtain a single breath EtO2 reading would be unethical as it would interfere with proper pre-oxygenation in a critically ill patient. A better method would be to examine end-tidal oxygen measurements from patients in real-time as they are being pre-oxygenated. This study will examine the use of a real time nasal cannula EtO2 sensor as compared to the gold standard of a single breath exhalation into a static sensor. Healthy participants will be randomly assigned to use the non-rebreather mask or the non-invasive ventilator. A baseline EtO2 measurement will be obtained with the nasal cannula EtO2 sensor then the mask the participant was randomized to use will be placed over the nasal cannula EtO2 sensor and oxygenation trials will begin. At the end of each trial a single breath end-tidal oxygen measurement will be obtained.