Every anesthesia practitioner dreads airway disasters. Anesthesiologists and nurse anesthetists are airway experts, but anesthesia professionals are often the only person in the operating room capable of keeping a patient alive if the patient’s airway is occluded or lost. Hypoxia from an airway disaster can lead to brain damage within minutes, so there is little time for human error.
A fundamental skill is the ability to assess a patient’s airway prior to anesthesia. One must assess whether the patient will pose: 1) difficult bag-mask ventilation, 2) difficult supraglottic/laryngeal mask airway placement, 3) difficult laryngoscopy, 4) difficult endotracheal intubation, or 5) difficult surgical airway.
Of critical importance is #1) above, that is, recognizing the patient who will present difficult mask ventilation. Conditions that make for difficult bag-mask ventilation are uncommon, and usually can be detected during physical examination. Despite the importance of expertise in endotracheal intubation, I teach residents and trainees that the most important airway skill is bag-mask ventilation. Every year I encounter several patients who present unanticipated difficult intubations. In each of these patients, I’m able to mask ventilate the patient to keep them oxygenated while I try various strategies and techniques to successfully place an endotracheal tube or a laryngeal mask airway.
Most anesthesia airway disasters aren’t merely difficult intubations, but scenarios that are classified as “can’t intubate, can’t ventilate.” In these “can’t intubate, can’t ventilate” situations, the anesthesiology professional has only minutes to restore oxygenation to the patient or else the risk of permanent brain damage is very real.
The American Society of Anesthesiologists Difficult Airway Algorithm is a guide for anesthesia practitioners regarding how proceed in airway management. The algorithm is detailed, complex, comprehensive, and defines the standard of care in any medical-legal battle concerning hypoxic brain damage due difficult airway clinical cases. The algorithm is so detailed, complex, and comprehensive that some would say it’s impossible to remember every step in the acute occurrence of an airway disaster.
A simplified approach has been touted.
Dr. C. Philip Larson, Professor Emeritus, Anesthesia and Neurosurgery, Stanford University, and Professor of Clinical Anesthesiology at UCLA, and previous Chairman of Anesthesiology at Stanford, was one of my teachers and mentors for both endotracheal intubation and fiberoptic intubation. In a Letter to the Editor of the Stanford Gas Pipeline in May, 2013, Dr. Larson wrote, “there is no scientific evidence that anesthesia is safer because of the ASA Difficult Airway Algorithm. While an interesting educational document, I question the daily clinical value of this algorithm, even in its most recent form (Anesthesiology 2013; 118:251-70). The ASA Difficult Airway Algorithm was developed by committee and has all the problems that result when done that way. It is complex, diffuse, multi-dimensional, and all-encompassing such that it is not an instrument that one can easily adopt and practice in the clinical setting.”
Dr. Larson recommends a system of Plans A-D, a system he published in Clinical Anesthesiology, editors Morgan GE, Mikhail MS, Murray MJ, Lange Medical publication, 4th edition, 2006, pp 104-5, and in Current Reviews in Clinical Anesthesiology (2009; 30:61-72), and also in the Appendix on airway management and intubation in the newest edition of Anesthesiologists Manual of Surgical Procedures by Richard Jaffe et al (Lippincott Williams and Wilkins, 5th Edition, May 2014). An outline of the system is as follows:
A. Plan A is direct laryngoscopy an intubation using a Miller or MacIntosh blade.
B. If Plan A is unsuccessful, Plan B includes use of video laryngoscopy with a GlideScope or similar device.
C. If Plan B is unsuccessful, Plan C is placement of an LMA with intubation through that LMA using a fiberoptic bronchoscope.
D. “If Plans A-C fail,” Larson wrote in his Letter to the Editor of the Stanford Gas Pipeline in May, 2013, “one needs Plan D. The first and perhaps the most prudent option is to cancel the proposed operation, terminate the anesthetic, and wake the patient up. The operation would be rescheduled for another day, and at that time an awake fiberoptic intubation technique would be used. Alternatively, if the operation cannot be postponed, then the surgeon should be informed that a surgical airway (i.e.: tracheostomy) must be performed before the planned operation can commence. To date, utilization of Plan D because of failure of Plans A-C has not occurred.”
Dr. Larson wrote that the airway skills in Plan A – C should be practiced regularly on patients with normal airways. I agree with Dr. Larson that in managing difficult airways, a practitioner needs a short list of procedural skills that he or she is expert at rather that a large array of procedures that they rarely use (such as the alternative intubation techniques using light wands or blind nasal techniques, or invasive airway procedures such as retrograde wires passed through the cricothyroid membrane or transtracheal jet ventilation through a catheter). It’s wise for anesthesiologists to regularly hone their techniques of video laryngoscopy (Plan B) and fiberoptic intubation via an LMA (Plan C) on patients with normal airways, to remain expert with these skills.
Regarding Plan B, an important advance is the availability of portable, disposable video laryngoscopes such as the Airtraq, a guided video intubation device. In my career I sometimes work in solo operating room suites distant from hospitals. In these settings, the operating room is usually not be stocked with an expensive video scope such as the GlideScope, the C-MAC, or the McGrath 5. I carry an Airtraq in my briefcase, and if the need for Plan B arises I am prepared to utilize video laryngoscopy at any anesthetizing location. I suggest the practice of carrying an Airtraq to any anesthesiologist who gives general anesthetics in remote locations.
Regarding emergency surgical rescue airway management, Dr. Larson recently published a Letter to the Editor in the American Society of Anesthesiologists Newsletter, February 2014, entitled, Ditch the Needle – Teach the Knife. In this letter, Dr. Larson wrote:
“in life-threatening airway obstruction, … an emergency cricothyrotomy is much quicker, easier, safer and more effective than any needle-based technique. I can state with confidence that there is no place in emergency airway management for needle-based attempts to establish ventilation. It should be deleted from the ASA Difficult Airway Algorithm. I have participated in seven cricothyrotomies in emergency airway situations, and all of the patients left the hospital without any neurological injury or complications from the cricothyrotomy. The risk-benefit ratio is markedly in favor the knife technique…. With a knife, or scissors, one cuts quickly either vertically or horizontally below the thyroid cartilage and there is the cricothyroid membrane or tracheal rings. The knife is inserted into the trachea and turned 90 degrees, and an airway is established. At that point, a small tube of any type can be inserted next to the knife. The knife technique is much safer because there is virtually nothing that one can harm by making an incision within two inches or less in the midline of the neck, and it can be performed in less than 30 seconds. In contrast, the needle is fraught with complications, including identifying the trachea, making certain that the needle is entirely in the trachea and does not move ( to avoid subcutaneous emphysema when an oxygen source is established), establishing a pressurized oxygen delivery system (which will take more than five minutes even in the most experienced circumstances), and avoiding causing a tension pneumothorax… I know of multiple cases of acute airway obstruction where the needle technique was attempted, and in all cases the patients died. I know of no such cases when a cricothyrotomy was used as the primary treatment of acute airway obstruction.”
A final note on the awake intubation of patients with a difficult airway: In hindsight in any difficult airway case, one often wishes they had secured an endotracheal tube prior to the induction of general anesthesia. The difficult problem is deciding prior to a case which patient has such a difficult airway that the induction of general anesthesia should be delayed until after intubation. In anesthesia oral board examinations it may be wise to say you would perform an awake intubation on a difficult airway patient rather than risk the “can’t intubate, can’t ventilate” scenario the examiner is probably poised to skewer you with. In medical malpractice lawsuits, plaintiff expert witnesses in anesthesia airway disaster cases often testify that a brain-dead patient’s life would have been saved if only the anesthesiologist had performed awake intubation rather than inducing general anesthesia first and then losing the airway. The key question is: how does one decide which patient needs an awake intubation? As an anesthesia practitioner, if you performed awake intubations on one out of 50 cases because you were worried about a difficult airway, you would delay operating rooms and surgeons multiple times per year because of your caution. You will not be popular if you do this. In my clinical practice and in the practice of the excellent Stanford anesthesiologists I work with, the prevalence of awake intubation is very low. I estimate most anesthesiologists perform between zero and two awake intubations per year. The most common indications include patients with severe ankylosing spondylitis of the cervical spine, congenital airway anomalies, and severe morbid obesity. Dr. Larson wrote in his Letter to the Editor of the Stanford Gas Pipeline in May, 2013, “I do anesthesia for most of the patients with complex head and neck tumors, and I find fewer and fewer indications for awake fiberoptic intubation. As long as the lungs can be ventilated by bag-mask or LMA, which is true for almost all sedated patients, Plan C is easier, quicker and safer than awake fiberoptic intubation both for the patient and the anesthesia provider. In experienced hands, Plan C can be completed in less than 5 minutes, and one can become proficient by practicing in normal patients. I have done hundreds of Plan C’s, many under difficult circumstances, without a single failure or complication. Obviously, no technique will encompass every conceivable airway problem, but mastering Plans A-D and awake oral and nasal fiberoptic intubation will meet the needs of anesthesia providers in almost all circumstances.”
May you never experience the emotional trauma of an airway disaster. Become an expert in bag-mask ventilation, always have access to a video laryngoscope or an Airtraq, and consider Dr. Larson’s Plan A-D system, described in detail in the Appendix on airway management and intubation in the newest edition of Anesthesiologists Manual of Surgical Procedures by Richard Jaffe et al (Lippincott Williams and Wilkins, 5th Edition, May 2014).