PreOxygenation for EndoTracheal Intubations

Hypoxemia is a life threatening complication during emergency airway management. Despite advances in technology and training, hypoxemia still occurs in up to a quarter of all intubations placing patients at high risk for damage to vital organs and death. A key method in the prevention of hypoxemia is known as preoxygenation which has been shown to decrease the incidence of hypoxemia. Currently there are two conventional methods for preoxygenation in the literature, however recently a new method has been described as a possible alternative method. What is unclear in the literature is if one modality is superior than the other for preoxygenation. The goal of this interventional study is to determine if one method of preoxygenation is superior to the other. This is a 3 arm interventional cross over designed study comparing three interventional methods for preoxygenation. Non-rebreather mask, bag-valve mask and high flow nasal cannulae.

In emergency and critical care medicine, one of the most common incidences of severe hypoxemia occurs during the process of endotracheal intubations. Endotracheal intubations, also known as insertion of a breathing tube, is a life saving technique used in medicine to help maintain oxygen delivery, to protect lungs from injury, for patients to safely undergo anesthesia for surgeries, as well as to help rest critically ill patients to allow their bodies time to recover. Despite advances in the field of medicine, the process of placing a breathing tube in emergency situations is still associated with an increase risk of hypoxemia up to 26.7%. This places patients at significant risk for cardiac dysrhythmia, brain damage and hemodynamic decompensation which may ultimately result in death. A UK national review of emergency intubations identified hypoxemia as a cause of death in 50% of intensive care intubations and 27% of Emergency Department intubations. Therefore, it is imperative to improve and develop methods to minimize hypoxemia during airway management.

A vital component used to minimize the risk of hypoxemia during endotracheal intubations is preoxygenation. Preoxygenation is a method to to prolong the time to oxygen desaturation by replacing the lung volume with 100% oxygen compared to 21% oxygen (room air) through the administration of supplemental oxygen. This increases the reservoir of oxygen in the lungs that the body can use to prolong their time to desaturation. Studies have shown a good preoxygenation technique can increase the time to oxygen desaturation from 0.6 min to 8 min in a non obese patient. This remarkable impact at preventing hypoxemia has made preoxygenation the gold standard to minimize hypoxemia during airway management.

Historically preoxygenation with bag-valve-mask ventilation (BVM) and an oxygen non-rebreather mask has been the standard for preoxygenation. Recently, the use of high flow nasal cannulaes have been used for preoxygenation however it is unclear in the literature if one provides a superior preoxygenation compared to another. In an effort to determine the best preoxygenation modality for airway management, the investigators will conduct a 3 arm interventional crossover designed study to compare preoxygenation using a non-rebreather mask, BVM and HFNC in 150 patients. To determine which modality provides the best preoxygenation, arterial blood gases will be taken after each intervention and compared against each other.

Given the high propensity for hypoxemia during airway management in the obese and disease lung population, this protocol will have specific groups based on their BMI (\<30, 30-35 and \>35) as well as the presence of lung disease based upon their PaO2/FiO2 ratio (\< 300 lung disease or \>300 no lung disease).

However, due to the pandemic, we had to pause recruitment, a decision was made to do an power analysis with the number of patients we had recruited and a decision was made to collapse the study and report or findings.

Eligibility Criteria:
Inclusion Criteria:

* Patients with a pre-existing arterial line
* Age \> 18
* Able to provide consent

Exclusion Criteria:

* Acute respiratory distress Defined as RR \>30, Baseline oxygen requirements \>50%, current use of High Flow Nasal Cannulae or Non-invasive ventilation for respiratory support
* Decreased level of consciousness GCS \<13
* Possible exclusion if the allocation to prespecified groups are filled
* Contraindication for high oxygen therapy Severe Chronic Obstructive Pulmonary Disease with documented CO2 retention based on outpatient ABG History of Bleomycin use
* Significant hemodynamic instability Lactate \> 3 mmol/L Norepinephrine dose \>0.2 mcg/kg/min or equivalent dose of other vasopressors