The authors reply
Xue et al (1) highlight that when comparing laryngoscopy devices, accounting for the experience of the operator performing intubation with each laryngoscopy device is critical. In the Facilitating EndotracheaL intubation by Laryngoscopy technique and apneic Oxygenation Within the intensive care unit (FELLOW) trial (2), we collected and adjusted for each operator’s previous intubating experience overall and previous intubating experience with the specific laryngoscopy device at the time of each intubation. This dynamic variable (overall and device-specific experience evolving over the course of the trial) is unique to the FELLOW trial and provides a granular account of operator’s device-specific experience than any previous trial of endotracheal intubation.
Xue et al (1) also raise the relationship between operators’ intubating experience and “proficiency.” Although intubating proficiency (defined variably) may occur after around 50 intubations in the operating room, the experience required to achieve proficiency during intubation of critically ill adults is unknown. Over the wide range of prior experience in our trial, we did not find that increasing device and procedure experience modified the effect of VL on first pass success. Most importantly for a trial comparing VL to direct laryngoscopy (DL), there was no signal in favor of VL among those with more experience, with the point estimate for first pass success actually favoring DL among those with greater than 50 prior intubations.
Xue et al (1) raise the point of the current trial not mandating the shape of the intubating stylet. In the ICU where the trial occurred, usual care is a straight-to-cuff stylet shape; however, since there are no definitive studies on how to shape a stylet we chose not to protocolize this technique.
Finally, Xue et al (1) point out that the reason for failure to intubate on the first laryngoscopy attempt was not systematically collected in the FELLOW trial. We would refer the reader to recent data from another trial of VL (3) suggesting that failed first attempts with VL are most commonly due to poor camera image and inability to pass an endotracheal tube into the trachea.
We performed a pragmatic trial to test the effectiveness of VL in an ICU with a heterogeneous patient and operator population while not mandating any other procedural aspects so that we can learn how VL performs in real world rather than highly controlled scenarios. Our data only indirectly speak to how VL would perform if all operators were very experienced with each device, if certain neuromuscular blocking drugs were used, and the shape of stylets were protocolized. Fortunately, we have other recently published randomized trials of VL in critically ill adults showing that our result was not likely a result of our study design. The findings are the same across the board: routine use of VL during endotracheal intubation of critically ill adults improves laryngeal visualization but does not increase procedural success or decrease complications (3–5).