Airway management is a cornerstone of anesthesiology, particularly management of potentially difficult airways, as anesthesiologists are the foremost experts in this arena. Anesthesiologists are acutely aware of how important it is to recognize a potentially difficult airway before administering sedation or anesthesia in order to avoid adverse events, including extended periods of hypoventilation, hypoxic brain injury, and death. The 2012 ASA Practice Guidelines for Management of the Difficult Airway defined a difficult airway as “the clinical situation in which a conventionally trained anesthesiologist experiences difficulty with face mask ventilation of the upper airway, difficulty with tracheal intubation, or both” (Anesthesiology 2013;118:251-70). These practice guidelines divided difficult airways into five categories: difficult facemask or supraglottic airway ventilation, difficult supraglottic airway placement, difficult laryngoscopy, difficult tracheal intubation, and failed intubation. Given the elevated risk of failed ventilation and/or intubation after induction of anesthesia in a suspected or known difficult airway, awake fiberoptic intubation with a flexible bronchoscope has long been considered by many anesthesiologists to be the gold standard for securing a difficult airway. In many settings, however, awake fiberoptic intubation can be time- and resource-consuming, and patients are often resistant to the procedure due to anxiety related to procedural awareness and fears of discomfort. The identification of additional modalities for the safe securement of potentially difficult airways would greatly benefit the field of anesthesiology.
A decade of progress
Arguably, the most widespread change in airway management since the publication of the 2012 Practice Guidelines for Management of the Difficult Airway has been the increased availability and use of video laryngoscope technology. The introduction of the video laryngoscope into clinical practice has improved the airway management of many patients who would previously have been categorized as having difficult airways. Often the impact of anatomic characteristics that cause a difficult airway can be minimized with the use of a video laryngoscope. Multiple randomized controlled trials comparing quality of glottic view obtained, intubation difficulty score, total necessary intubation attempts, and frequency of first-attempt and overall intubation success provide evidence that laryngoscopy with a video laryngoscope improves these parameters compared to traditional direct laryngoscopy in patient populations suspected to have difficult airways (Anesthesiology 2012;116:629-36; Sri Lankan J Anaesthesiol 2017;25:70; Br J Anaesth 2009;102:546-50; Med Princ Pract 2014;23:448-52; Br J Anaesth 2009;103:761-8; Eur J Anaesthesiol 2010;27:24-30). Additionally, multiple randomized controlled trials comparing awake video-assisted laryngoscopy with awake fiberoptic intubation techniques found no significant difference in the quality of laryngeal view obtained, time to obtain laryngeal view, frequency of first-attempt intubation success, total intubation time, or patient satisfaction with the procedure, thus supporting the use of video-assisted laryngoscopy as an alternative to fiberoptic intubation with a flexible bronchoscope in the setting of a suspected difficult airway (asamonitor.pub/3FuUEWV; Anesthesiology 2012;116:1210-6; Egypt J Anaesth 2012;28:257-60).
An updated version of the ASA Practice Guidelines for Management of the Difficult Airway was released earlier this year (Anesthesiology 2022;136:31-81). The updated guidelines incorporated the expertise of an international task force of anesthesiologists representing many different medical organizations. The definition of a difficult airway was expanded to situations when an “anticipated or unanticipated difficulty or failure is experienced by a physician trained in anesthesia care, including but not limited to one or more of the following: facemask ventilation, laryngoscopy, ventilation using a supraglottic airway, tracheal intubation, extubation, or invasive airway.” In these guidelines, emphasis has been placed on being cognizant regarding the passage of time during airway management, limiting airway management attempts, and monitoring oxygen saturation.
Building on the previous version of the guidelines, the general steps for management of the difficult airway provided in the 2022 guidelines include calling for help, optimizing oxygen delivery, utilizing available cognitive aids, using non-invasive airway devices, combining airway management techniques, utilizing invasive airway management techniques, and considering extracorporeal membrane oxygenation if available and appropriate. The method of airway management, as with the 2012 guidelines, should be based on the provider’s experiences. The creation of a management plan before airway management begins using a team-based approach is recommended to clarify resources and identify next steps should initial airway management attempts fail. The risks and benefits of both non-invasive and invasive approaches to the airway should be identified. The 2022 guidelines also place new emphasis on using either low-flow or high-flow nasal cannula throughout airway management and keeping the patient in the head up position if possible in order to facilitate oxygenation throughout airway securement. Testing the efficacy of mask ventilation and providing mask ventilation between airway management attempts is also recommended. Providers should consider using a combination of techniques in the face of a failed individual technique, consider using an invasive airway technique, or consider awakening the patient. Further, the 2022 guidelines provide expanded recommendations for extubation of a difficult airway including preformulating an extubation strategy involving thoughtful selection of the extubation time, location, and participants; considering the use of an airway exchange catheter, primarily in adult patients; determining the risks and benefits of elective tracheostomy before extubation; and providing supplemental oxygen during the extubation process.
Airway management remains the cornerstone of anesthesia and has evolved immensely as the field has advanced. Over the past decade, the expanded use and clinical study of video laryngoscopy in the suspected difficult airway has demonstrated this technology to be a valuable new tool in difficult airway management. The most recent version of the ASA Practice Guidelines for Management of the Difficult Airway combines this new clinical data with the recommendations of an international group of experts to provide a robust framework to guide anesthesiologist management of a difficult airway. Anesthesiologists will always strive to develop novel technology, systems-based practices, airway management techniques, and expertise in order to increase the safety of airway management in patients with suspected difficult airways.