In Reply:
We thank Dr. Knapp for highlighting our recent article on prediction of difficult tracheal intubation.1 We agree with his comments. Indeed, he raised two major issues: the first one is the lack of universal definition for difficult tracheal intubation and the second one is when such a difficulty has been predicted, it is not the end of the story based on anatomic thoughtfulness, but the beginning of solutions according to various strategies related to new devices such as videolaryngoscopes overcoming a difficult laryngoscopy with conventional direct laryngoscopy.
Requirement of an alternate technique to conventional laryngoscopy seems an important way to define, even nowadays, a difficult airway. It means you overcome the difficulty with another device alone or in adjunct to the conventional laryngoscope. Nevertheless, you have already succeeded in performing tracheal intubation, but the “therapeutic pressure” was not the same. For example, in septic shock patients with the same mean arterial pressure of 65 mmHg, if in one case a norepinephrine support is 0.5 mg/h and in another case 5 mg/h for norepinephrine support, seriousness of these patients is obviously totally different.
The main paradigm change in difficult tracheal prediction we tried to highlight in our article was to decrease the proportion of patients in the inconclusive zone (gray zone) to implement an optimized airway management strategy according to the patient’s risk, with the necessity or not to master a difficult tracheal intubation with an appropriate alternate technique to conventional laryngoscopy or to maintain this standard technique by excluding such a difficulty. This anticipated difficulty in a given patient is an a priori approach and is different from the one using an established algorithm to achieve successful tracheal intubation by incorporating various advanced airway devices due to conventional laryngoscopy failures.2 In this last feature, the approach was a posteriori, managing the difficulty when it occurred with a predefined procedure. But in both cases, it moves the lines from a static predicting failure model relying only on an anatomical model, i.e., Mallampati classification, to a dynamic success model with implementation of newer airway devices to overcome the difficult airway pushing the limits of difficult tracheal intubation definition. This was indeed the true paradigm change we emphasized.
