In critically ill adults undergoing emergency tracheal intubation, hypoxemia (low levels of oxygen in the blood) increases the risk of cardiac arrest and death.
In current clinical care, most critically ill adults receive preoxygenation using an oxygen mask. Preoxygenation is the administration of supplemental oxygen prior to the start of a procedure to increase the content of oxygen in the lung and decrease the risk of hypoxemia during the tracheal intubation procedure.
Semler is a senior principal investigator for the trial and co-author on the study. He also chaired the Steering Committee for the Pragmatic Critical Care Research Group that led the trial.
Researchers at the University of Wisconsin School of Medicine and Public Health were involved in the Department of Defense-funded Pragmatic Trial Examining Oxygenation Prior to Intubation (PREOXI) clinical trial, led nationally by Vanderbilt University University Medical Center. The trial compared the two most commonly used methods to preoxygenate patients prior to tracheal intubation: preoxygenation with noninvasive ventilation and preoxygenation with an oxygen mask.
The study, published June 13 in the New England Journal of Medicine, showed that the noninvasive ventilation method (a way to support breathing by using a tight-fitting respiratory mask connected to a BPAP — bilevel positive airway pressure — machine) reduced the risks associated with the intubation procedure.
“More than 1.5 million critically ill adults undergo emergency tracheal intubation each year in the United States,” said Jonathan Casey, MD, MSCI, assistant professor of Medicine in the Division of Allergy, Pulmonary and Critical Care Medicine at VUMC and a senior principal investigator in the trial.
“Hypoxemia occurs during 10% to 20% of those tracheal intubations in the emergency department or intensive care unit and may lead to cardiac arrest and death. Our study found that among critically ill adults undergoing tracheal intubation, preoxygenation with noninvasive ventilation decreases the incidence of hypoxemia during intubation compared to preoxygenation with an oxygen mask.”
The multicenter, randomized trial was conducted in 24 emergency departments and intensive care units in the United States. Critically ill adults undergoing tracheal intubation were randomly assigned to two groups: preoxygenation using noninvasive ventilation or preoxygenation using an oxygen mask.
The investigators hoped that preoxygenation with non-invasive ventilation would prevent hypoxemia during intubation, defined as an oxygen saturation less than 85% during the interval between induction and two minutes after tracheal intubation.
In the 1,301 patients enrolled, hypoxemia occurred in 57 of the 624 patients (9.1%) in the noninvasive ventilation group and 118 of the 637 patients (18.5%) in the oxygen mask group. Further, it appeared that by preventing hypoxemia during tracheal intubation, preoxygenation with non-invasive ventilation also prevented cardiac arrest, the most feared complication of tracheal intubation, which occurred in one patient (0.2%) in the noninvasive ventilation group and seven patients (1.1%) in the oxygen mask group.
Prior to this trial international guidelines stated that preoxygenation with either noninvasive ventilation or an oxygen mask is acceptable – guidance that results of this trial are likely to change.
Kevin Gibbs, MD, the first author on the study and a critical care medicine physician at Wake Forest University School of Medicine, said, “Applying these results to clinical care by routinely using noninvasive ventilation for preoxygenation before tracheal intubation has the potential to prevent tens of thousands of patients each year from experiencing hypoxemia and cardiac arrest.”
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