Matt Semler, MD and colleagues performed an RCT on Apneic Oxygenation in Medical ICU patients. I got a chance to sit down and interview him on the trial.

The Trial

The Fellow Trial (Published ahead of Print)

Bottom Line Review

Trial Summary

Additional Written Comments from Matt Semler

as provided by Matt Anderson (@ccinquisivist)

From: Anderson, Matthew J

Dr Semler

I'm a CCM fellow at the University of Wisconsin, interested in airway mgmt in the ICU.

Just saw your article published in ATS. I had a question about the airway mgmt protocol (or if there was one?). Did the airway team leader/intubator maintain a patent airway (ie were they instructed to do this just prior to the intubation attempt when getting sedation/analgesia and/or NMB)? I am unable to find/get to the supplement which this information may be listed but I didn't see any mention in the main manuscript, which I think is a extremely important discussion point. Previous, studies in the OR w/ or w/o maintenance of airway patency resulted in 'no difference in the non-airway patency (ie jaw thrust/head tilt chin lift) group vs 'stat significant difference in the airway patency group' during apneic oxygenation. If airway patency was maintained in your study this would be one of the first 'negative' results I have seen with apneic oxygenation. If airway patency was not required, this may explain the 'no difference' that was found in your study, which in my opinion, makes the use of apOX still an important part of endotracheal intubation. Until a randomized control trial to evaluate apOx with airway patency versus no apOx with airway patency confirms that previous. Further trials may need 30 degree ramp/optimal positioning, as well?

Thanks for taking the time to answer my questions and publish/perform important ICU airway research.

Matt Anderson

Critical Care Medicine Fellow, PGY5

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From: Semler, Matthew

Matt,

Thanks for your interest in the trial.  You ask two really important questions -- actually two of the same points Rich Levitan emphasized when he visited during the conduct of the trial.

(1) When discussing the effect of airway patency on outcomes of apneic oxygenation, the time-period in question is between administration of RSI medications (with anything prior to induction technically a part of pre-oxygenation) and the onset of laryngoscopy (when patency of the airway is directly established by the laryngoscope better by external maneuvers).  Objectively assessing whether the airway is patent during this period is challenging.  For the 30% or so in the trial who were on BIPAP between induction and laryngoscopy, the airway was known to be patent through monitoring of the returned tidal volumes.  In cases where NIV was not present, the operator was charged with maintaining patency of the airway between induction and laryngoscopy.  In 60% of cases this required an oral airway and a head-tilt-chin-lift maneuver.  In around 40 patients, the operator felt the airway was patent without such a maneuver.  Whether these maneuvers were effective in maintaining patency or whether patency was truly present in those patients who were not felt to require a maneuver is difficult to know.  We did analyze the subgroup of those who were on BIPAP and we were certain the airway was patent and there was not a significant effect of apneic oxygenation on lowest oxygen saturation in this group -- though obviously this is a not a large population.

An important thing to consider when thinking about the period between induction and laryngoscopy is that high flows of oxygen...