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A universal classification for videolaryngoscopy using the VIDIAC score requires real world conditions: a reply

We thank Dr’s Lee andChoi for their interest in our work and for emphasising the importance of participating airway operators when interpreting airway studies [1]. It is well known that airway operator skill and experience affect performance of tracheal intubation [2]; therefore, skilled senior airway operators are often favoured participants in interventional studies. However, this should not be confused with the videolaryngoscopic intubation and difficult airway classification (VIDIAC) study [3], which is a prospective observational multivariable prediction model development and validation study. As the VIDIAC study intended to develop a simplified, intuitive and easy-to-use clinical score reflecting real-world clinical practice conditions, it must be based on data from a representative spectrum of consecutive patients and airway operators. From our perspective, an important strength of the VIDIAC study is the large variety of different airway operators involved because a universal classification of videolaryngoscopic intubation should be applicable to all airway operators, not only to themost experienced. Moreover, similar to Cormack and Lehane, our intention was to provide novice physicians and trainees with a reliable grading system to encourage training and aid in decisionmaking [4]. Novices represent the most important target group of the VIDIAC score. We would certainly have missed this goal if we had purposefully involved a higher proportion of senior airwayoperators.Overall, 81 anaesthetists (42 (52%) women; 69 (85%) trainees) with amedian (IQR [range]) age of 30 (28–32 [26–51]) y and 18 (8–40 [1–168]) months of anaesthetic experience participated in the VIDIAC study. According to our institutional standards, all videolaryngoscopic tracheal intubations, particularly in patients undergoing rapid sequence induction, were performedwith deep neuromuscular blockadewith train-offour monitoring throughout. As we planned to include patients who received multiple anaesthetics, we ensured that study-specific airway assessments and outcome variables were recorded separately from clinical notes. Additionally, no patient’s tracheawas intubated by the same operator more than once. A sensitivity analysis showed that multiple observations per patient did not impact VIDIAC score performance. The gender-specific median (IQR [range]) VIDIAC scores were 1 (−1–2 [−1–5]) for females and 1 (−1–3 [−1–5]) for males; tube sizes were 6.5 (6.5–7.0 [5.0– 7.5]) mm for females and 7.0 (7.0–8.0 [5.0–8.5]) mm for males. However, we believe the tracheal tube size findings obtained from patients undergoing laparoscopic surgery cannot be extrapolated to those with difficult airways undergoing ear, nose and throat or oral and maxillofacial surgery [1]. Previous difficult tracheal intubation is a strong predictor of future difficult tracheal intubation [5]. The VIDIAC study aimed to develop a specific, scalable classification system tailored to integrate with digital applications such as electronic health records, software, registries and electronic alert cards to drive the digital transformation in airway management. In our opinion, the VIDIAC cohort and the outlined clinical setting provide the perfect environment in which a universal classification tool and decision-making aid could be particularly beneficial.