Why Are Difficult Airway Carts Necessary?

The concept of difficult and failed airway carts is not a novel one. These carts usually serve two purposes:

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  Managing the anticipated difficult airway. As such they contain special devices (e.g., atomizers, Jackson Crossover forceps) and medications (e.g., lidocaine 5% ointment, lidocaine 4% aqueous) used to perform an awake intubation (see Chapter 3).

  
  
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  Managing the failed airway. To this end they have devices (e.g., extraglottic devices [EGDs]) and prepackaged kits (e.g., open cricothyrotomy) used to manage the failed airway in an emergency.

Ordinarily, a single “airway” cart serves both functions and the contents do not vary significantly from unit to unit, except perhaps in regard to pediatrics where size-related variations must be accounted for. The equipment, supplies, devices, and medications that they contain ordinarily are not otherwise immediately available on the majority of clinical units. For example, the difficult airway cart for the operating room (OR) rarely contains endotracheal tubes (ETTs), laryngoscopes, and stylets, as they are in every OR. On the other hand, in the post-anesthesia care unit (PACU), the critical care unit (CCU), and the emergency department (ED) difficult airway carts may well have these devices in the cart.

It has long been acknowledged that having emergency equipment readily available in a reliable location is a standard of care. The “cardiac crash cart,” for example, is a mandatory addition to ORs, EDs, and other patient care areas where they may be required. Many labor and delivery rooms have an “emergency cart” ready for unanticipated “crash” cesarean sections, while trauma units have an emergency surgical setup for occasions when a chest or abdomen must be rapidly opened.

Although the literature is relatively silent on the actual benefits of having a difficult airway cart available for an emergency, there is strong consensus among experts that the ready access to alternative devices for airway management has the potential for reducing risks and complications in the management of the unanticipated difficult airway.^1–3 In 1993, the American Society of Anesthesiologists Task Force on Management of the Difficult Airway published their Practice Guidelines for Management of the Difficult Airway.¹ This document, subsequently updated in 2003 and 2013, contained a clear statement that “at least one portable storage unit that contains specialized equipment for difficult airway management should be readily available.”^2,4 They followed with a suggested list of specialized equipment that this “storage unit,” or cart, should contain (Table 62–1).

Beyond the scope of the original ASA guidelines, the Canadian Airway Focus Group reviewed the pertinent literature on airway management in Canada and published recommendations for the management of the unanticipated difficult airway.³ This group recommended that a “difficult airway cart” be available for emergency airway interventions in addition to the standard airway equipment available in every OR. They also suggested a minimum equipment list for such a cart.

It is important to note that two significant changes to the cart content recommendations have been made since the last edition of this text:

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   The cricothyrotomy kit must contain equipment to perform an OPEN cricothyrotomy⁵;

   
   
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   The difficult airway cart must contain lidocaine 5% ointment and lidocaine 4% aqueous for atomization, in accordance with the three-step topicalization procedure of the upper airway recommended in Chapter 3.

Is There Any Evidence That Difficult Airway Carts Are Beneficial in the Setting of Difficult or Failed Airway Management?

The literature is replete with the advantages of using alternative airway devices in situations where a difficult airway is encountered, both anticipated and unanticipated. Just as emergency drugs and the presence of a defibrillator on the “crash cart” are indispensable in the management of a cardiac emergency, the readily available rescue airway devices in an airway emergency clearly represent an improvement in patient care.

The increase in morbidity and mortality associated with difficulties in airway management is well recognized.^6,7 Both the ASA and Canadian Airway Focus groups recommend limiting the number of attempts at direct laryngoscopy to three and two, respectively.^1–3 Mort⁸ has shown that the increasing numbers of attempts at intubation by direct laryngoscopy correlate with an increased incidence of respiratory and hemodynamic complications. In this study, a database was created to record complications following emergency airway interventions outside the OR. When three or more attempts were made to secure an airway by direct laryngoscopy, the incidence of hypoxemia increased from 11% to 70%, regurgitation from 2% to 22%, aspiration from 0.8% to 13%, and cardiac arrest from 0.7% to 11% (Table 62–2). One could speculate that the presence of alternate airway devices would have prevented the need for repeated attempts at direct laryngoscopy.

Mort⁹ reviewed the incidence and etiology of out-of-OR cardiac arrests occurring during emergency intubation before and after the introduction of emergency airway carts. In 1995, the institution, a level-one trauma center, introduced airway carts, or kits containing “advanced” airway equipment and tracheal tube verifying devices. A retrospective study compared the time periods of 1990 to 1995 and 1995 to 2002 for a number of variables, the primary comparator being cardiac arrest. The compelling results showed an overall reduction of 50% in airway-related cardiac arrests between the two time periods, attributable to the presence of the carts (Figure 62–1).⁹

Although the data compiled from these papers were gathered from non-OR locales, the conclusions are clearly applicable to all areas that airway management may be performed, including the OR. The ready accessibility of difficult airway carts is indispensable in reducing airway-related morbidity and mortality.

What Steps Should be Taken to Ensure That the Carts Remain Well Stocked and Contain Equipment in Good Working Order?

It is important that when an airway practitioner arrives at the scene of an airway emergency, or when the “Difficult Airway Cart” is summoned, all of the equipment that is needed must be present and functional. To achieve this, departmental and hospital policies or processes must be crafted, which should identify:

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  the numbers and locations of such carts;

  
  
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  a process of annual review of the cart locations and how they are equipped and updated;

  
  
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  a qualified staff member must be responsible for the cart in each assigned area as the “keeper of the cart”;

  
  
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  how equipment is added to and deleted from the standard list of contents, and how such changes are suggested, vetted, implemented, and communicated to the relevant staff;

  
  
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  how the drawers will be arranged and labeled;

  
  
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  how equipment with schedules are to be maintained (e.g., bronchoscopes);

  
  
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  time frames and responsibilities regarding replenishment after equipment is used;

  
  
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  who will check the inventory and how often it will be checked. The checklist includes the functioning of essential equipment, such as bulbs and batteries, and time-sensitive supplies such as local anesthetic agents and vasoconstrictors;

  
  
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  If cleaning is to be done, who will do it, how it will be done (e.g., bronchoscopes), and how long the “out of service for cleaning” interval will be;

  
  
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  an inventory of replenishment supplies to be kept immediately on hand, particularly disposables (e.g., EGDs, open cricothyrotomy kit, etc.);

  
  
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  where equipment manufacturers’ literature will be kept.

Routine airway management equipment that one expects to use in most, if not all, airway management emergencies, such as laryngoscopes, airways, ETTs, intubating stylets (e.g., Eschmann Introducer or Frova), tonsil and catheter suction devices, etc., should be immediately available and not clutter the drawers of the cart. As mentioned above, this equipment need not be on an OR cart as each anesthetizing location ought to have them available. Carts should be located in each area of the hospital where airway management might reasonably be expected to occur, such as EDs, coronary care unit, cardiac catheterization units, labor and delivery suites, endoscopy suites, diagnostic imaging units, and other locations where sedatives will be administered. In locations where both children and adults are cared for, the pediatric cart should be distinctly separate from the adult cart (different style, and perhaps different color). An array of ETT sizes, masks, oral and nasal airways, etc., must be easily accessible in the event pediatric patients are cared for. Perhaps the best system currently available to meet this need is the Broselow–Luten System^®.¹⁰ Alternatively, canvas-pocketed systems that are rolled up for storage can easily and quickly be unrolled to access the equipment.

If at all possible, airway carts should be in a consistent location (e.g., with the cardiac crash cart). The cart should be secured with a plastic twist removable lock. The cart is secured after each check, signaling that the cart has been replenished and is ready for use. The absence of the lock signifies that the cart needs immediate inspection. A keyed lock may be required for drawers that contain medications. The locking mechanism for this drawer must be limited to this drawer only and should not impede access to the other drawers with airway devices.

What Are the Guiding Principles for Establishing a Difficult Airway Cart for the OR Area?

Historically, the contents of the “difficult airway cart” in most anesthesia locations varied widely, as various practitioners demanded the addition of newer or their preferred devices. Unfortunately, items that nobody had ever used, or would ever use, were included. The contents would often be forgotten, and little or no maintenance would occur. Basically, they were difficult airway carts in name only.

Although a number of publications describe difficult airway cart setup, most are simply a description of the author’s departmental cart.¹¹ However, such a list can be a good starting point for creating a useful cart, with the end users customizing the contents according to departmental needs, preferences, and available resources. A designated individual or committee should be responsible for soliciting input from users in determining what should be on the cart. The decision about the contents ought to be reviewed quarterly or semiannually to ensure that carts have the most up-to-date and effective equipment. Deletions and additions need to be communicated to all users in a timely manner.

In principle, the cart should be one that is easily accessible and has equipment familiar to the users and other unit personnel. An assortment of well-arranged and quickly accessible devices should be available to handle most needs. Decisions about disposable versus reusable equipment should be made consistent with hospital policies and published evidence of equipment effectiveness (discussed later in this chapter).

In this all-inclusive difficult airway cart, all equipment needed for difficult airway situations (so-called Plan B and Plan C) should be present. As mentioned, equipment on the cart need not duplicate routine airway equipment otherwise available on anesthetic carts in the ORs. This may be where an OR difficult airway cart differs from airway carts in other locations: in ICU or ED settings, airway kits or carts may contain both routine and alternative airway equipment.

Familiarity with the difficult airway cart and its contents is crucial. Using “difficult airway” equipment for routine intubations will add to the skills in using alternative devices and will also help the anesthesia practitioner, and support personnel, gain needed familiarity with cart contents and location. This in turn will lead to more effective management of an emergency unanticipated difficult and failed airway, minimizing stress for all concerned. However, with regular use of the difficult airway cart, there must be a routine to ensure that it is properly maintained: disposables must be replenished and reusable equipment disinfected, and replaced as quickly as possible (see section “Disposable versus Reusable Devices Considerations for Difficult Airway Carts” in this chapter). This in turn implies that designated personnel familiar with the cart routinely check and replenish it. This is the same principle that applies to maintenance of the cardiac arrest “crash cart.”

What Equipment Should be Available on a Difficult Airway Cart for the OR?

The cart containing the equipment should be mobile, small enough to be safely and easily moved by one person, and should fit into the ORs through the doorways. It should be located in a central location that is familiar and visible to all. Smooth castors on the cart and the drawers are important to ensure that the cart does not become an obstacle in itself, and is safe from being overturned. Cables and cords should be neatly attached so that nothing can be snagged while the cart is being moved or people are working around it. Failure to pay attention to this could lead to damage to equipment or injury to staff. The drawers should be clearly labeled as per their contents.

The equipment included on the cart should cover the range of options that might be needed in a difficult airway scenario. This will include categories such as:

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  equipment to facilitate mechanical (bag-mask or EGD) ventilation;

  
  
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  adjuncts to direct and indirect laryngoscopy (e.g., tracheal introducers);

  
  
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  alternatives to direct laryngoscopy (e.g., video-laryngoscopes, lightwands, etc);

  
  
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  equipment to facilitate transtracheal access (e.g., cricothyrotomy kit);

  
  
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  light sources, cameras, and monitors for techniques requiring, or facilitated by, this equipment;

  
  
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  equipment and drugs for application of topical airway anesthesia or airway blocks;

  
  
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  miscellaneous equipment as determined by the location and facility.

What Equipment to Facilitate Mechanical (Bag-Mask or EGD) Ventilation Should be Included in the Difficult Airway Cart for the OR?

At least one bag-mask device should be available for delivery of positive pressure ventilation. Nonstandard mask sizes (i.e., very large and very small) may belong on the cart. The group or individual responsible for the airway cart should decide which EGDs to stock. If LMA Classic^® or disposable LMAs are routinely stocked in an OR cart, then the cart may contain an LMA ProSeal^® and intubating LMA (LMA Fastrach^®). Other EGDs such as the King LT^® airway can be considered, but the devices should be the ones with which the department members have experience and have found useful. Second-generation EGDs (those with esophageal/gastric drainage tubes such as the King LTS-D^®, LMA Proseal^®, LMA Supreme^®, LMA Protector™, iGel^®, etc.) should be considered, especially in the wake of the findings of NAP4 where aspiration was the most common cause of death.^12,13

What Adjuncts to Direct Laryngoscopy Should be Included in a Difficult Airway Cart for the OR?

An assortment of alternate blades designed to fit standard laryngoscope handles used in the OR should be available. For example, Miller (straight) and Macintosh (curved) blades of various sizes, as well as levering tip (McCoy) laryngoscope blades, might be kept in this section. The presence of a variety of ETTs (e.g., Endotrol™, Microlaryngeal Tubes™, GlideRite™) not routinely stocked in the OR, including a range of smaller sizes, is important.

The presence of a flexible, Coudé-tipped (distal 2.5 cm angled approximately 35 degrees) Eschmann Tracheal Tube Introducer (the “gum-elastic bougie”), the SunMed Bougie™, Pocket Bougie, or the single-use Cook Frova™ is an essential addition to an emergency cart. It can be guided below the epiglottis when a Mallampati Class II or III view of the larynx is encountered, whereupon the ETT can be advanced over it (see section “What Is the Eschmann Tracheal Tube Introducer? How Does It Facilitate the Placement of an Endotracheal Tube?” in Chapter 12). Because they should be kept straight (except the Pocket Bougie), rather than bent to fit into a drawer, some tracheal tube introducers (e.g., Portex™) may be stored in their original shipping case, secured to the side of the cart (Figure 62–2). As a simple, yet useful device, most would suggest that these introducers be an integral part of standard equipment found in every room or location where airways are routinely managed (e.g., anesthetizing locations, ED resuscitation rooms, etc.).

What Alternatives to Direct Laryngoscopy and Rescue Devices Should be Included in a Difficult Airway Cart for the OR?