The routine use of apneic oxygenation during endotracheal intubation of critically ill adults does not necessarily increase oxygen saturation compared with usual care, a recent study has concluded.
“Interventions that appear effective in the highly controlled environment of the operating room [OR] frequently fail to translate to critically ill patients in the ICU,” said Matthew Wall Semler, MD, of the Division of Allergy, Pulmonary and Critical Care Medicine at Vanderbilt University School of Medicine, in Nashville, Tenn., and lead author of the study, which was published in American Journal of Respiratory and Critical Care Medicine (2016;193:273-280). The findings were also presented at the Society of Critical Care Medicine’s 2016 Critical Care Congress (abstract 149).
A Pragmatic Setting Outside the OR
The pragmatic randomized trial compared 15 L per minute of 100% oxygen via a high-flow nasal cannula during laryngoscopy (apneic oxygenation) with no supplemental oxygen during laryngoscopy (usual care) with regard to lowest arterial oxygen saturation between induction and two minutes after completion of endotracheal intubation. The term “pragmatic” emphasizes the setting of the trial as a routine, real-life situation.
The trial included 150 adults undergoing endotracheal intubation in a medical ICU. In contrast to previous small studies in the OR, this trial showed no difference between apneic oxygenation and usual care.
“This is the first randomized trial of apneic oxygenation outside the operating room and is five times bigger than any prior trial of apneic oxygenation,” Dr. Semler said. The median lowest arterial oxygen saturation was 92% with apneic oxygenation versus 90% with usual care (95% CI for the difference, 21.6% vs. 7.4%; P=0.16). There was no difference between apneic oxygenation and usual care in the incidence of oxygen saturation less than 90% (44.7% vs. 47.2%; P=0.87), oxygen saturation less than 80% (15.8% vs. 25.0%; P=0.22) or decrease in oxygen saturation greater than 3% (53.9% vs. 55.6%; P=0.87). Duration of mechanical ventilation, ICU length of stay and in-hospital mortality were similar between study groups.
Results Disappointing But Not Surprising
Dr. Semler noted that a recent study, in which patients received a higher dose of apneic oxygenation (60 L/min), demonstrated similar findings (Intensive Care Med 2015;41:1538-1548).
While Dr. Semler called the results disappointing, he said they were not necessarily surprising. “Those patients with severe underlying pulmonary dysfunction who are most in need of an intervention to prevent desaturation during intubation may be precisely the group for whom administration of supplemental oxygen during apnea will have the least effect,” Dr. Semler said.
Patients undergoing endotracheal intubation in the ICU are at high risk for hypoxemia for several reasons, Dr. Semler noted. “Unlike in the operating room, where the indication for intubation is often airway protection during a procedure, or the emergency department, where the indication for intubation is often altered mental status, patients undergoing intubation in the medical ICU often have underlying respiratory failure prompting intubation, and many of these patients are hypoxemic before the procedure even begins.”
Peter Papadakos, MD, director of critical care medicine at the University of Rochester Medical Center, in New York, agreed that patients in the ICU frequently have severe shunt and ventilation/perfusion mismatch that might limit the benefits of supplemental oxygen, but thought further study of apneic oxygenation in patients with preserved pulmonary function or large areas of atelectasis was warranted.
Ultimately, the study concluded that its findings do not support routine use of apneic oxygenation during endotracheal intubation of critically ill adults. “To prevent desaturation during endotracheal intubation,” Dr. Semler said, “providers should focus on maximizing the oxygen saturation at the time of induction—preoxygenation—and employ a consistent approach to sedation, neuromuscular blockade and laryngoscopy that allows successful placement of the endotracheal tube in the shortest interval possible.”