The American Society of Anesthesiologists (ASA) just published a 2022 update on their ASA Difficult Airway Algorithm Guidelines. The 2022 document is a revision of the 2013 publication “Practice guidelines for management of the difficult airway: A report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway.” The 2022 ASA Difficult Airway Algorithm Guidelines are 51 pages in total.
The most important changes are identified by examining the 2013 and the 2022 algorithms side by side. Let’s look at the 2013 flow chart algorithm and compare it to the 2022 flow chart algorithm below:
Note these major changes from 2013 to 2022:
- The top third of the 2022 algorithm lists factors which direct the anesthesiologist to perform awake intubation. The reason for this change is undoubtably the wisdom of utilizing awake intubation when a significant risk of a difficulty airway exists. There are minimal airway risks when a patient is awake, and the benefit of placing the endotracheal tube in a difficult airway patient while the patient is awake is immense. When we give mock oral board examinations to anesthesia residents at Stanford, and we describe to the examinee that the patient has a difficult airway, the answer of “I’d do an awake intubation” is hard to criticize and almost never leads to a catastrophe. In contrast, inducing general anesthesia prior to intubation in these patients can lead to a “Can’t intubate-can’t oxygenate” emergency, which can lead to a cardiac arrest and possible anoxic brain damage.
- The text highlighted in red in the 2022 document is both new and vital. The first of these is “OPTIMIZE OXYGENATION THROUGHOUT,” under the pathway INTUBATION ATTEMPT WITH PATIENT AWAKE, with the footnote 2Low- or high-flow nasal cannula, head elevated position throughout procedure. Noninvasive ventilation during preoxygenation. The message is to keep oxygen flowing via nasal cannula throughout airway management attempts to minimize hypoxia, and to keep the head elevated to maximize the functional residual capacity (FRC), which is the reservoir of oxygen in the patient’s lungs.
- “LIMIT ATTEMPTS, Consider calling for help” is new and printed within a red box in the INTUBATION ATTEMPT AFTER GENERAL ANESTHESIA –> FAILED pathway. This is an effort to prevent repetitive unsuccessful intubation attempts from soaking up precious time, during which the brain is poorly oxygenated.
- “LIMIT ATTEMPTS AND CONSIDER AWAKENING THE PATIENT” is new and printed in red in the NON-EMERGENCY PATHWAY under the “Ventilation adequate/intubation unsuccessful” pathway. This is again an effort prevent repetitive unsuccessful intubation attempts from soaking up precious time, during which the brain is poorly oxygenated.
- “LIMIT ATTEMPTS AND BE AWARE OF THE PASSAGE OF TIME, CALL FOR HELP/FOR INVASIVE ACCESS” is new and printed in red in the EMERGENCY PATHWAY under the MASK VENTILATION NOT ADEQUATE, SUPRAGLOTTIC AIRWAY NOT ADEQUATE pathway. This is again an effort to prevent repetitive unsuccessful intubation attempts from soaking up precious time, during which the brain is poorly oxygenated.
These changes, printed or boxed in red, emphasize that the pace of difficult airway decisions is important. The duration of elapsed time is vital. When an anesthesia provider cannot intubate the patient and then cannot ventilate the patient, the oxygen level in the blood can plummet. There is a significant danger of anoxic brain damage within minutes. I’ve previously reviewed this topic in a 2019 Anesthesia Grand Rounds Lecture at Stanford, summarized in my article “Five Minutes to Avoid Anoxic Brain Damage.” The U.S. Library of Medicine website states that “Brain cells are very sensitive to a lack of oxygen. Some brain cells start dying less than 5 minutes after their oxygen supply disappears. As a result, brain hypoxia can rapidly cause severe brain damage or death,” and “Time is very important when an unconscious person is not breathing. Permanent brain damage begins after only 4 minutes without oxygen, and death can occur as soon as 4 to 6 minutes later.”
The sentence “Be aware of the passage of time, the number of attempts, and oxygen saturation” appears more than once in the 2022 Difficult Airway Algorithm Guidelines article, and is a key point for all anesthesia providers who encounter a difficulty airway emergency.
In my roles as an anesthesia quality assurance reviewer or a medical-legal expert consultant, I’ve seen this issue arise multiple times. Even though anesthesia providers believe they are following the Difficult Algorithm accurately, they are doing things too slowly, and they waste too much time. Once it’s clear that a “Cannot intubate-cannot oxygenate” scenario is occurring, the time clock is running, and the anesthesia provider must not only do the correct thing but he or she must do the correct thing without undue delay. The necessary procedure may be as invasive as a cricothyroidotomy/front of the neck access via the scalpel-bougie-endotracheal tube approach.
The five points listed above are the major changes in the algorithm. In addition, the new 2022 article includes a Pediatric Difficult Airway Algorithm and an approach to Extubation of the Trachea in a Difficult Airway Patient. Other important quotes from the 2022 article include (bold emphasis added):
- “The consultants and members of participating organizations strongly agree with recommendations to perform awake intubation, when appropriate, if the patient is suspected to be a difficult intubation and difficult ventilation (face mask/supraglottic airway) is anticipated.”
- “Meta-analyses of randomized controlled trials comparing video-assisted laryngoscopy with direct laryngoscopy in patients with predicted difficult airways reported improved laryngeal views, a higher frequency of successful intubations, a higher frequency of first attempt intubations, and fewer intubation maneuvers with video-assisted laryngoscopy.”
- The footnote (7) for alternative difficult intubation approaches states: 7Alternative difficult intubation approaches include but are not limited to video-assisted laryngoscopy, alternative laryngoscope blades, combined techniques, intubating supraglottic airway (with or without flexible bronchoscopic guidance), flexible bronchoscopy, introducer, and lighted stylet or lightwand.
- “A randomized controlled trial comparing a videolaryngoscope combined with a flexible bronchoscope reported a greater first attempt success rate with the combination technique than with a videolaryngoscope alone.”
- “When appropriate, refer to an algorithm and/or cognitive aid.”
AUTHOR’S NOTE: I’d suggest that the Stanford Emergency Manual of cognitive aid algorithms for anesthesia and ACLS emergencies be onsite at all anesthetizing locations.
I’d also recommend that the 2022 ASA Difficult Airway guideline algorithm be onsite at all anesthetizing locations.
Every anesthesia professional will encounter patients with difficult airways—this is one of the most important and most feared situations in our specialty. Commit the 2022 ASA Difficult Airway Algorithm to memory. Use awake intubation when you’re concerned about the potential of a “Cannot intubate-cannot oxygenate” scenario. And if you’re in the middle of a difficult airway emergency, call for help and be aware of the passage of time, the number of attempts, and the oxygen saturation. Don’t let an excessive number of minutes elapse without regaining oxygenation of your patient.