Stylet vs. flexible-tip bougie: interpreting intubation outcomes with hyperangulated videolaryngoscopy in the ICU

Abstract

We thank Makar et al. [1] and Hsu et al. [2] for their thoughtful comments on our article [3] and appreciate the opportunity to clarify and contextualise our findings.

As noted, the first-pass tracheal intubation success rate in the stylet group of our study was 83%, which Makar et al. [1] found surprisingly low. However, this figure aligns closely with data from large-scale, high-quality studies conducted in intensive care settings. For example, in the DEVICE trial, which included over 1400 adults who were critically ill and undergoing tracheal intubation in emergency departments and ICUs, the first-pass tracheal intubation success rate using videolaryngoscopy was 85%, with standard geometry blades used in 86% of cases and hyperangulated blades in 14% [4]. In that trial, a stylet was used in 55% of patients and a bougie in 42%. Similarly, in the INTUBE study of nearly 3000 patients who were critically ill, the first-pass tracheal intubation success rate with videolaryngoscopy was 84%, with a stylet used in 77% of cases and a bougie in 22% [5]. These rates are consistent with those observed in our own study.

In contrast, the studies cited by the authors [6, 7] were conducted in the operating theatre in elective surgical patients. This is fundamentally different from the ICU in terms of patient physiology, procedural urgency and available resources. Notably, both studies reported first-pass tracheal intubation success rates exceeding 97%, figures that are not representative of the realities and complexities of airway management in patients who are critically ill. To our knowledge, no large ICU-based series have reported first-pass intubation success rates > 90%.

Airway management in the ICU is challenging due to physiological issues, haemodynamic instability and unpredictable anatomy. Although 73% of operators were residents who were familiar with hyperangulated videolaryngoscopes, this does not invalidate the study results or prevent meaningful device comparisons. Crucially, our study was designed to evaluate the performance of these two introducers (stylet vs. flexible-tip bougie) under ‘real-world’ ICU conditions, and we believe our findings reflect their clinical utility in such settings accurately.

We agree with the correspondents that operator training and technique are critical, particularly when using hyperangulated videolaryngoscopes with a stylet. Our protocol included a standardised approach to stylet shaping, with an angulation of at least 30–40° in the distal 5 cm of the tube. This is consistent with critical care practice and previously published studies. Operators were free to further increase the angulation if necessary, although a limitation of our study is that we did not record the exact angle used in each case. While alternative techniques such as shaping the stylet to match the blade curvature or adjusting glottic exposure, may improve performance, these approaches have yet to be validated in large-scale ICU trials. We fully support future research aimed at optimising such techniques and integrating them into structured training programmes.

In summary, our results reflect ‘real-world’ performance in a high-risk population and align with outcomes reported commonly in critical care. However, the 99% first-attempt tracheal intubation success using a flexible-tip bougie supports the availability of this device in critical care settings. While both technique and equipment selection can influence outcomes, we emphasise that the ICU environment differs significantly from the operating theatre and must be assessed in its own context.