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Certain patients should raise red flags throughout your facility when they present for surgery: the morbidly obese, patients with obstructive sleep apnea or congenital malformations and pregnant women who may have airway edema. These individuals are at increased risk for difficult airways, but you can avoid potential complications if you follow this straightforward advice.
1 Plan ahead
Patient assessments should include a review of the airway and any head and neck issues that might make intubation more difficult, including previous surgery, trauma, infections and acquired or congenital malformations.
The following physical attributes may predict airway challenges: long central incisors, moderate overbite, a high arched palate, poor visualization of the uvula (Mallampati Class > II), greater than 3 finger breadths thyromental distance, a thick, short neck, and limited range of motion in the head and neck. While the Mallampati rating system (see "What Can You See?" on page 21) provides some predictive value regarding the potential difficulty of the airway, relying on a single element of the history or physical exam could lead to an unrealistic impression of the impending airway challenge.
Acquire any history of anesthetic airway difficulties, which should be noted in prior records of anesthesia care. Some patients may even have a medic alert bracelet or letter from a facility's anesthesia department that explains the difficulties providers had in securing their airways for surgery. Reviews of previous anesthesia records may provide clues about the successes and difficulties that other providers had with airway management, such as challenges encountered with mask ventilation or endotracheal intubation, and the maneuvers that ultimately helped secure the airway.
Your airway management strategies must be based on multiple factors, including the patient's history and physical, the surgical procedure about to be performed, airway equipment availability, the clinical skills of the provider and availability of additional skilled anesthesia personnel. For certain elective procedures, when non-routine airway equipment or additional personnel are unavailable, seriously consider postponing surgery or transferring the patient to a facility that may have these resources readily available.
A step-by-step process that considers the factors for successful ventilation, intubation or tracheostomy will lead to improved outcomes (see "Take Pre-Op Assessments Seriously" on page 20).
SUPPLY MANAGEMENT
Essential Tools for Difficult Airway Management
Have a difficult airway cart stocked and ready, in addition to routine airway equipment. While the contents of the cart will vary by facility, here's a list of devices to consider storing in yours:
- rigid video laryngoscope blades of various sizes
- tracheal tubes
- hollow or rigid guides and stylettes
- lighted stylettes
- laryngeal mask airways
- oral and nasal airways
- flexible fiber-optic scopes
- percutaneous cricothyrotomy kits
- transtracheal jet ventilator
- retrograde wire
- end-tidal or exhaled carbon dioxide color-change detector
— Gary Friedman, MD
2 Improve the view
Video laryngoscopes are becoming increasingly popular tools for managing the difficult airway (see "Video Laryngoscopy Ideal for Obese Patients"). These devices have dramatically improved providers' abilities to view the larynx in patients with challenging airway anatomy. Video laryngoscopy is especially useful during intubations when the larynx cannot be seen with direct visualization into the orophayrnx. Rather, the only — or optimal — view of the larynx is obtained on the laryngoscope's monitor due to the relative location of the scope's imaging fiber-optics to the larynx.
This imaging capability has revolutionized airway management and reduced patient morbidity and mortality. It remains to be seen whether video laryngoscopes will eventually become a standard of care for every anesthetic, but it is clear that this technology should be readily available in the event difficulties arise (see "Essential Tools for Difficult Airway Management" on page 17).
AIRWAY ASSISTANCE
Video Laryngoscopy Ideal for Obese Patients
Video laryngoscopes let anesthesia providers see structures during intubations that might otherwise be obscured to the naked eye, say airway experts Davide Cattano, MD, PhD, and Carin Hagberg, MD, of the University of Texas Medical School at Houston.
In a 2010 Anesthesiology News guide to intubating obese patients, they call the imaging technology an "excellent option" for securing the difficult airway. Video laryngoscopy can be used to establish airways after traditional approaches fail or as a first option for providers familiar with the technology and expecting a challenging intubation, the guide notes
.Drs. Cattano and Hagberg say video laryngoscopes are especially effective for intubating obese patients, who often present with short, large necks, large tongues or folds of tissue around the mouth and pharynx that can make intubation challenging. In addition, obese patients experience a larger reduction in lung volume than lean patients do, which hastens the need for establishing the airway quickly and effectively.
With the large and complete view of the airway afforded by video technology, providers are often able to overcome or avoid common intubation obstacles they face when caring for obese patients. For example, notes the guide, providers can watch the advancement of the laryngoscope and alter its movements if needed for more precise placement and prevention of injuries or damage to airway structures. Video laryngoscopes also enable providers to establish airways with less movement of the patient's head and neck, a key to caring for obese individuals whose thicker and larger anatomy can make manipulation difficult.
On the way to concluding that video laryngoscopy should be considered as the primary intubation method, Drs. Cattano and Hagberg point to several of the technology's advantages: intubations can be recorded, saved and stored; it's ideal for educational purposes; and providers can rely on the intubating techniques they'd use with traditional laryngoscope blades.
In addition, notes the guide, failed intubations during video laryngoscopy are often attributable to user error, but "with more practice, failures are almost, if not entirely, eliminated."
— Daniel Cook
3 Consider regional
When dealing with a potentially difficult airway, alternatives to general anesthesia with a breathing tube must be considered. Is monitored anesthesia care an option? What about a mask general or total intravenous anesthetic? Would a peripheral nerve block, spinal or epidural work? Regional anesthesia helps providers avoid altogether securing difficult airways in high-acuity patients. When considering any of the alternatives to general anesthesia, however, always plan for what will happen if regional blocks, spinals or epidurals fail. Of course, the argument can always be made that securing the airway primarily instead of as the alternative might be the most prudent care choice in cases involving difficult airway management. This decision is often the most difficult for providers to make, and must be handled on a case-by-case basis depending on the nature of the surgery and the patient's condition.
ANESTHESIA ALERT
Take Pre-Op Assessments Seriously
Poor airway assessments contribute to poor airway outcomes, according to a study in the February 2011 issue of the British Journal of Anaesthesia.
Providers who altered their airway management techniques based on the finding of pre-op assessments could have prevented about three-fourths of major airway-related complications reported over the course of a year. The study's researchers discovered, however, that a lack of skill or confidence, poor judgment and, in some cases, a lack of appropriate equipment prevented providers from using the clinically indicated airway technique. In addition, providers tended to repeat failed intubation attempts, even when another course of action would have been the preferred choice.
The report also notes that obese patients were 4 times more likely to develop serious airway complications than the general patient population, but problems caring for the obese arose during procedures that could have potentially been avoided if local or regional anesthesia was used, which was not considered in some cases.
The study's authors suggest that managing the potential difficult airway demands a coordinated, logical sequence of plans instead of a single-approach airway plan.
— Daniel Cook
4 Position for success
High-acuity patients must always be positioned for optimal intubation and airway patency. Proper positioning depends on the patient's age, body type and chest habitus. Placing the adult patient's head on a pillow or blankets in the "sniff" position usually will let providers perform direct laryngoscopy in a way that aligns the other structures of the upper airway with the larynx, resulting in ideal intubating conditions. In some cases, depending on the choice of direct-vision blades, video laryngoscope or flexible fiber-optic scope, putting the patient in a back- or head-up, sitting or wedged position may improve visualization of the larynx.
MALLAMPATI CLASSIFICATIONS
What Can You See?
This measures your visualization of the patient's uvula, faucial pillars and soft palate. Higher scores can predict a difficult intubation.
- Class I: Visualization of the soft palate, fauces; uvula, anterior and the posterior pillars.
- Class II: Visualization of the soft palate, fauces and uvula.
- Class III: Visualization of soft palate and base of uvula.
- Class IV: Only hard palate is visible. Soft palate is not visible at all.
— Gary Friedman, MD
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