The authors reply
Mendelson et al (1) cite a recent study by Silverberg et al (3) comparing VL and DL for intubation of critically ill adults using a Glidescope rather than the McGrath MAC video laryngoscope (Medtronic, Minneapolis, MN), which was used in 98.6% of the intubations in the Facilitating Endotracheal intubation by Laryngoscopy technique and apneic Oxygenation Within the ICU (FELLOW) trial (2). This is an important difference between the study by Silverberg et al (3) and the FELLOW trial suggesting that the data on the McGrath MAC may not be generalizable to patient care scenarios where the Glidescope is being used for intubation. Although certainly possible, we would argue that our data remain generalizable to video laryngoscopes as both studies demonstrated improved glottic view with VL; these two devices are not functionally different (both aim a camera at the glottis), and an effect size of 34% seen in the study by Silverberg et al (3) is likely overestimated (4) and not likely to carry over to clinical practice. The large effect size seen in the study by Silverberg et al (3) may be due to a number of factors pointed out by Mendelson et al (1). In addition, unlike the FELLOW trial, the study by Silverberg et al (3) was not a randomized trial that further biases toward an overestimation of an effect size (5) (device assignment was not random, but uniformly alternated between even and odd numbers of intubations for each operator in which the operator knew which would be the next device assignment).
Mendelson et al (1) also inquire as to the definition of aspiration in the FELLOW trial (2). After completion of the procedure, the operator was asked if periprocedural aspiration had occurred based on their own subjective definition of aspiration. Given the unreliable nature of self-reported data during airway management (6) and the lack of a uniformly accepted objective definition, we urge caution in comparing the aspiration event rate in our trial to other trials. Self reporting of data is a common limitation of intubation studies, which is why the FELLOW trial used independent observers not participating in the procedure or the trial to record the majority of the trial outcomes.