The safety of topical lidocaine for awake tracheal intubation: a reply

We thank Evans et al. [1] for their comments and interest in the Difficult Airway Society (DAS) guidelines on awake tracheal intubation (ATI) [2] and their suggestion of a remifentanil-only sedation technique. In developing the ATI guidelines, we made every attempt to base the recommendations, not only on the highest available supportive evidence, but also on the applicability of this evidence to safe clinical practice. The guidelines have been designed to improve patient safety and aim to support clinicians who do not regularly perform ATI; they are not designed for experts who regularly perform this procedure. Awake tracheal intubation can be safely and effectively performed without sedation [3], but there are advantages to using minimal levels of sedation, such as amnesia or reducing patient anxiety and discomfort. However, the risks of oversedation include loss of a previously patent airway, apnoea, hypoxia, aspiration and reduced levels of patient co-operation. These have been the most common complications reported during ATI [3, 4]. However, the complications of airway obstruction due to local anaesthesia are rarely reported. Hence, we have recommended the cautious use of minimal sedation, and encouraged appropriate local anaesthetic topicalisation. Evans et al. have suggested a single-agent remifentanil technique for ATI, stating that it has a better safety profile than a topicalised lidocaine technique. However, they refer to a study where cocaine 5% solution was administered to the nasal mucosa in conjunction with remifentanil, and the authors acknowledged that some degree of anaesthesia to the oropharynx and glottis could not be excluded [5]. Despite this use of remifentanil, 70% of the participants reported mild, moderate or severe discomfort during the procedure and 75% coughed when the tracheal tube was passed through the vocal cords. Evans et al. also state “this theoretical concern is borne out in multiple case reports of airway collapse following lidocaine topicalisation for awake tracheal intubation in which several patients required emergency front of neck airway access” [6]. Firstly, the evidence provided is a single patient case report in which a supine patient with existing upper airway obstruction was successfully intubated orally under flexible bronchoscopic guidance following total airway obstruction. This airway obstruction was a result of a number of contributing factors, not solely due to airway topicalisation. Secondly, the authors of that report themselves suggested that sedation is not recommended in a patient with a seriously compromised airway as this may worsen the airway obstruction, further reducing support for a remifentanil-only sedation technique. We believe that the use of Evans et al.’s suggested technique is not appropriate for patients with partial airway obstruction and should not be performed by clinicians unfamiliar with the technique as it is associated with an increased risk of complications. We thank Evans et al. for providing the opportunity to clarify the reasons why the DAS ATI guidelines did not recommend a remifentanil-only technique and we encourage clinicians to follow what they believe to be safest practice.