End-Tidal OxygenEnd-Tidal Oxygen for Intubation in the Emergency Department

The control period includes a period whereby clinicians will not have access to ETO2 monitoring and routine RSI practices will be documented including all study variables. At all institutions, RSI is performed in a similar manner, utilising an airway checklist. There is no 'standard operating procedure' for RSI in any of the EDs and methods, therefore, vary depending on clinician preference and the condition of the patient, however, each site is a tertiary-level, university teaching hospital and therefore clinical practice is up to date and evidence-based. Standard preoxygenation methods in the Emergency department often consist of a bag-valve mask, with or without a PEEP valve, set at 15L/min, or the use of non-invasive ventilation or a non-rebreather mask, with or without a nasal cannula, set at 15 L/min or flush rate oxygen (>40 L/min). US sites have access to high-flow (>30L/min) oxygen. This is the only difference in the preoxygenation method.

For all patients involved in the study, the only intervention will be the use of ETO2 to guide preoxygenation. All aspects of RSI will be at the discretion of the treating clinician including sedative/paralytic medications, positioning of the patient, preoxygenation method, intubation techniques and post-intubation sedation.

Clinicians will be encouraged to aim for the highest ETO2 result possible with a goal of >85%. Clinicians will be able to view the ETO2 values and can decide on any changes to the preoxygenation techniques if deemed necessary. These techniques may include improved patient positioning, improved face mask seal, increased oxygen flow, length of preoxygenation time, or altering the preoxygenation device.

The only additional equipment required for this study is the Philips™ IntelliVue G7m Gas Analyser Module 866173. This provides a non-dispersive infrared measurement of respiratory gases and a paramagnetic measurement of oxygen. At Lincoln Medical Center, the gas analyser used will be a Philips G5 gas analyser connected to a Philips Intellivue MP 70. At the University of New Mexico Medical Center, the Masimo root monitor is used.

The gas analysers produce display waves for O2 and CO2, together with numerics for end-tidal values for O2 and CO2 and to our knowledge, there are no differences in values between the various devices used. The gas sampling occurs through a side-stream sampling tube at a rate of 200ml/min ±20 ml/min, which is either obtained from a nasal cannula in the spontaneously breathing patient or a sidestream line if connected to a BVM.