Fifteen years ago, I left my practice in academic anesthesia to help open and run a small ambulatory surgery center (ASC). By small, I mean two operating rooms. In the beginning, I was often the only anesthesiologist (or anesthesia provider) in the building. I still remember the mix of excitement and trepidation that greeted those early days. I was confident in my abilities but worried about the lack of help should an emergency arise. I was particularly concerned about airway emergencies as they were/are the leading cause of anesthesia-related serious morbidity and mortality. It didn’t help my angst that the first step in the ASA Difficult Airway Algorithm when encountering an airway emergency was “Call for help.”
I’m back in academic anesthesia now, but as chair of the ASA Committee on Ambulatory Surgical Care and secretary of the Society for Ambulatory Anesthesia (SAMBA), I have kept my interest and contacts in the ambulatory arena. Difficult airway management and lost airway are still major concerns for ambulatory anesthesiologists, especially isolated practitioners such as office-based anesthesiologists. “Call for help” is still the first step in last year’s updated ASA Difficult Airway Algorithm. This article will discuss some of the issues surrounding airway management in ambulatory surgery.
In the ambulatory practice, airway emergencies are often related more to unrecognized or improperly treated ventilation problems since so much of ambulatory surgery is done without intubation, especially in offices and smaller venues. In 2010, a group of us from the SAMBA Committee on Office Based Anesthesia presented an abstract on quality assurance data from six large office based practices spread around the U.S. Eighty-six percent of our 50,000 cases were performed using deep sedation or general anesthesia without an airway. While GI and dental sedation cases represented over half our patient population, only 6 percent of all patients were intubated. Managing patients without airway devices requires constant and careful observation of ventilation and illustrates the importance of the ASA’s recent emphasis on end-tidal CO2 monitoring.
There are multiple advantages to avoiding intubation in ambulatory surgery. Older studies touted efficiency, hemodynamic stability, lower anesthetic requirements, and decreased coughing and sore throat when LMAs were compared to endotracheal intubation. More recent work suggests additional benefits: decreased postoperative nausea, vomiting, fewer postoperative analgesic requirements and shorter PACU stays.
But supraglottic airway devices (SADs) are not a panacea.1 As recently reported in the 4th National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society (NAP4), poor planning and inappropriate use of SADs can lead to aspiration and/or inadequate ventilation. They noted that reported events had “a disproportionate number of patients with BMI > 35” and cautioned against use of SAD to avoid intubation in patients with known airway difficulty. This last point strikes me as controversial and may be in flux with the increased use of alternate intubation techniques, especially videolaryngoscopes. If intubation is not required, one might manage these patients with a SAD as long as precautions are taken. The keys are: 1) no anticipated problems with ventilation or aspiration risks; 2) no anticipated difficulty with supraglottic placement – though not much to guide one here; 3) conventional use only – no prone positioning for these patients; and 4) adequate back-up plans, including specialty equipment and the expertise to use them effectively.
This leads to another important question: should we anesthetize patients with a history of difficult intubation in freestanding ambulatory settings? Here again, I think it depends on available resources. Some larger ASCs are staffed and equipped like a hospital, while smaller ASCs might look more like office-based surgical practice. Each center will need to decide what it’s capable of and what it’s comfortable with. I would recommend avoiding anesthetizing patients with a known difficult airway in the smaller venues.
Another common question: “What airway equipment should be on hand in an ASC or office environment?” The follow-up question is usually, “do I need a fiberoptic scope for intubation?” Most of the data come from decade-old surveys, and at that time fiberoptic bronchoscope was the most popular device used to manage anticipated difficult intubation and/or failed intubation by direct laryngoscopy. We looked at our experience here at Mayo (inpatients and outpatients) in 2005 and reported 60 percent of failed intubations by direct laryngoscopy were subsequently intubated with fiberoptic bronchoscopy.2 Of course, this was before the adoption of videolaryngoscopy, which has caused a paradigm shift in airway management. If we repeated our study today, I am confident videolaryngoscopy would be the preferred method of rescue. Investigators from SUNY Buffalo surveyed ICU difficult airway cart contents in 2010 and found 48 percent of carts had videolaryngoscopes but only 38 percent stocked fiberoptic bronchoscopes.3 In addition, the latest revision of the ASA Difficult Airway Algorithm now includes videolaryngoscopes in the assessment, management choices and “alternate approaches to intubation” sections of the algorithm.
The revision also gives a list of suggested contents of a “Portable Storage Unit for Difficult Airway Management.” Here again, videolaryngoscopes are prominently mentioned as are different laryngoscope blades, tracheal tube guides, supraglottic airways and flexible fiberoptics. Equipment suitable for emergency invasive airway access is also recommended. They are careful to say these are just suggestions and should be customized as needed. For ambulatory anesthesia, especially an office-based practice, customizing means addressing portability and durability issues. My ideal cart would include several different supraglottic airway devices (LMA-based and laryngeal tube, for example) as well as emergency cricothyroid jet ventilation and surgical airway kits. I recommend becoming facile with at least two alternative intubating devices, and my first choice right now is videolaryngoscopy. (I was/am a big fan of the Trachlight, but it is currently not being manufactured). Videolaryngoscopy really has revolutionized the way we think about difficult airway management and fits perfectly in the ambulatory anesthesiologist’s armamentarium.4-6
A multitude of studies has demonstrated outstanding success rates (95 percent or higher) with minimal side effects.7 These devices are sturdy, portable, and easy to clean or even disposable. There are many studies comparing different devices in mannequins, normal airways and difficult airway situations. These studies show mixed results and essentially equal success rates.8 My recommendation is to find one you’re comfortable with and practice to proficiency in that device.
Two areas of caution: first, while the failure rate is very low, it is not zero. It is imperative that alternate intubation and ventilation techniques are available. Moreover, other than neck pathology and limited mouth opening, the risk factors for difficult videolaryngoscope are not well defined. Second, the studies on awake videolaryngoscopy are just starting to come out.9-11 While early results suggest a high success rate, the numbers are small and I don’t think we’ve come to the point yet where videolaryngoscopes have replaced awake fiberoptic intubation. If you are anesthetizing these high-risk patients, I would recommend access to and proficiency with fiberoptic bronchoscopy as well as additional skilled personnel nearby. Again, these are probably not the patients for small ASC- or office-based practices.
I do think videolaryngoscopy has shifted the airway equation away from awake fiberoptic intubation. An informal poll of my colleagues here at Mayo Clinic found a universal change in practice. Everyone I asked had induced general anesthesia and used primary videolaryngoscopic intubation in patients whom they previously would have performed awake fiberoptic intubation (all successfully intubated, I might add). This trend will no doubt grow as familiarity and expertise in videolaryngoscopy increases. Another word of caution here: this strategy is only viable for patients with no contraindications to mask ventilation or risk factors for difficult mask ventilation (beard, snoring, edentulous, BMI >30 or age >55). Remember, the failure rate for videolaryngoscope intubation is not zero, so always err on the side of caution, with preservation of ventilation/oxygenation as the ultimate goal.
Airway management is evolving rapidly with ambulatory anesthesiologists on the cutting edge. Newer portable and durable devices have increased the armamentarium of ambulatory anesthesiologists and serve as excellent rescue devices in unanticipated difficult intubations. Videolaryngoscopes also expand the options for patients with known difficult airways but do not eliminate the need for alternate intubation and ventilation techniques and adequately trained personnel to aid in rescue.
Michael T. Walsh, M.D. is Assistant Professor of Anesthesiology, College of Medicine, Mayo Clinic, Rochester, Minnesota.