Regarding the letter from Drs. Nielsen and Lim addressing mask ventilation, we respectfully disagree with the letter’s premise stating that “the new ASA Difficult Airway Guidelines shift a paradigm on mask ventilation: the definition of difficulty now emphasizes patient outcome.”2 The 2022 update has the same focus on patient outcomes as the original guidelines (1993)4 and of previous updates (20035 and 20136 ); each of the published ASA Difficult Airway evidence-based practice parameters have addressed patient outcome in both the evidentiary information collected and in the final recommendations.
We appreciate Drs. Nielsen and Lim’s assessment of capnography as an objective, immediate, and visible measure for assessing adequate mask ventilation, and their reference to a scale for reporting ventilatory outcomes based on end-tidal carbon dioxide. Although our guideline development process did not evaluate such a scale, perhaps with additional evaluation and validation it could be considered in a future practice parameter.
The letter from Dr. Stein et al. on the use of airway exchange catheters in pediatric patients questioned the recommendation to “minimize the use of an airway exchange catheter with pediatric patients.”1 They accurately addressed the limited available literature addressing this topic for pediatric patients. They noted that survey responses from consultants and members of participating organizations (addressing all patients, both adult and pediatric) strongly agreed with the primary recommendation to “assess the relative clinical merits and feasibility of the short-term use of an airway exchange catheter and/or supraglottic airway that can serve as a guide for expedited reintubation.”3 This recommendation was followed by the subrecommendation to “minimize the use of an airway exchange catheter with pediatric patients.”3
Dr. Stein et al. additionally noted, as we did, that literature reporting adverse events in adult difficult airway patients, such as airway exchange catheter failure, trauma, pneumothorax, and death, was extremely limited in the pediatric patient population. To minimize such potential harms to pediatric difficult airway patients, we placed the recommendation to minimize the use of airway exchange catheters in this population after the recommendation to address the “relative clinical merits and feasibility” of the short-term use of airway exchange catheters. These recommendations contain a footnote as follows: “These interventions are considered advanced techniques.” The Task Force exercised caution for both this recommendation and the subrecommendation due to the paucity of evidence (particularly in the pediatric population) and the consideration that some advanced techniques such as airway exchange catheter may not be commonly used by a majority of adult or pediatric anesthesiologists. Although experienced anesthesiologists who have considerable clinical expertise with this technique may use airway exchange catheters successfully in their own practices, the lack of evidence of the safety of this practice in this population led to the subrecommendation to “minimize the use of an airway exchange catheter.”
Dr. Stein et al. recommend preferentially providing oxygen by other means (e.g., simple facemask) when possible, and “if rescue ventilation via an airway exchange catheter is needed, use the minimum pressure necessary to achieve chest wall rise and allow adequate time for exhalation” followed by “additional risk mitigation steps include advancing the catheter no further than the distal tip of the endotracheal tube, noting the depth marking, securing the catheter to prevent distal migration, and obtaining imaging, as indicated.” Unfortunately, at the time of publication, we had no evidentiary information to address these interventions either.
We do agree that airway exchange catheter use needs to be re-addressed to assess whether airway exchange catheters have value for pediatric difficult airway patients and encourage those who have experience with this technique to publish their experience. We certainly intend to revisit this topic when the current guidelines are updated in the future. Thank you for your valuable feedback.
Dr. Hagberg reports the following financial relationships: Ambu (Ballerup, Denmark), Karl Storz Endoscopy (El Segundo, California), Vyaire Medical (Mettawa, Illinois), UptoDate (Waltham, Massachusetts), Elsevier (Amsterdam, Netherlands), Teleflex (Wayne, Pennsylvania), Fisher & Paykel Healthcare Limited (Auckland, New Zealand), Lucid Lane (Los Altos, California). The other authors declare no competing interests.