“If you can’t breathe, nothing else matters.” This phrase has been spoken by countless patients and clinicians for many years and is as profound as it is simple. Maintaining the patient’s breathing is the number-one priority in any patient emergency; but achieving airway control, for a variety of reasons, may prove to be difficult. One part of the problem is attributable to the frequently stressful circumstances. Other factors such as poorly trained providers, patients with anatomical anomalies, or a lack of equipment may also contribute. The paragraphs that follow address these issues and offer some advice on how airway emergencies can be more effectively and efficiently managed.
When to Intubate
Airway emergencies typically involve any or all of the following: difficult ventilation, difficult intubation, or difficult tracheotomy. Regardless of the cause of the emergency, the goals are to secure the airway and minimize the likelihood of hypoxemia, regurgitation, and aspiration. Endotracheal intubation is the method of choice to accomplish all these goals. If this cannot be immediately accomplished, bag mask ventilation (BMV) should be provided. It may require the assistance of two people, but as long as the patient can be oxygenated, BMV can continue and alternative strategies to secure the airway can be organized. If BMV cannot sufficiently oxygenate the patient, an esophageal tracheal combitube, a supraglottic airway, or laryngeal mask airway could be more effective. If the patient cannot be ventilated and cannot be intubated, surgical procedures such as cricothyrotomy or retrograde intubation should be carried out.
Many times the decision to intubate is based on the patients’ inability to protect their own airways. The presumption has been that in the absence of a gag reflex, the patient is likely to aspirate. This concept has been called into question by one source who reports that a significant segment of the normal adult population lacks a gag reflex.1 The author suggests that the ability to swallow secretions actually requires a higher level of neurologic function and may be a better indicator of when to intubate for airway protection. In one study, a Glasgow Coma Scale score of less than 8 was shown to correlate better with the patient’s ability to protect their airway and the subsequent need for intubation.2
Patient mortality and morbidity can be adversely affected by waiting too long to intubate. Smoke inhalation patients, particularly those with facial burns, should be intubated before they start wheezing. Patients in anaphylaxis should be intubated before they exhibit stridor. Any patient in shock is inherently unstable and should be intubated.
Preparing to Intubate
To prevent the possibility of aspiration, surgical patients are not allowed to eat or drink for several hours prior to surgery. Clearly, this will not be the case for almost all patients brought to the emergency department. For patients who need to be intubated quickly, rapid sequence intubation (RSI) is the preferred technique for preparing them. Rapid sequence intubation includes the virtually simultaneous administration of two agents—a sedative and a neuromuscular blocking agent. Their cumulative effects will render the patient unconscious and flaccid. This will expedite securing the airway and prevent aspiration. Patients who present with little or no respiratory or cardiac activity are unlikely to react to having the laryngoscope placed in their mouths and RSIs will not be indicated.
There are circumstances where administration of sedatives and paralytics should be avoided. In patients who are grossly obese, use of these drugs could create more problems than they solve. This is because the pharmacological effects will not be limited to skeletal muscle. The redundant pharyngeal tissue frequently observed in these patients loses its natural tone. Instead of seeing recognizable anatomy, the person intubating will likely see a morass of featureless pink tissue. Additionally, if the patient is placed in the customary supine position, the effects of gravity increase the physical strength required to displace the tissue and expose the airway.
A more effective strategy would be to attempt what is called the awake intubation and obviously would be attempted only in awake patients. The process starts by sitting patients upright. They should have very little or no sedation. To minimize coughing and gagging, an aerosol of a topical anesthetic should be applied to the patient’s mouth and upper pharynx. If time allows, a drying agent can also be given to minimize oral secretions. The endotracheal tube should be inserted using a fiberscope fed through it. The person intubating is facing the patient. A bite block should also be placed to minimize the chance for damage to the fiberscope (see Figure 1).
|Figure 1. Awake intubation.|
Difficult airways are also classified as failed airways or crash airways. Regardless of what they are called, they require special attention because of the tendency for harm to the patient and the increased incidence of catastrophic events. Patients with difficult airways will have more intubation attempts and experience more trauma. One study reports that lip lacerations and bruises were reported at a rate of 5% for patients with normal airways. In patients where intubation required multiple attempts, the rate increased to 63%.3
Guidelines for management of the difficult airway have been developed by several sources, including the American Society of Anesthesiologists (ASA). The association’s algorithm has been used in countless hospitals and has undergone periodic revision since its introduction in 1993.4 The algorithm suggests that if the unexpected occurs, the anesthesiologist consider canceling the case. Unfortunately, this option is not available to those who work in critical care.
Airway emergencies are always easier to manage if they can be anticipated. Several scoring systems have been developed to aid practitioners in determining the likelihood of airway problems. Measurement of the thyromental distance is one (see Figure 2). Others that are recommended are Mallampati and Cormack-Lehane systems. There are several problems with using any of these methods:
- They require a certain amount of time to complete;
- Some require a certain amount of cooperation from the patient; and
- When used individually, their predictive power is far less than perfect. They have poor-to-fair specificity and only moderate sensitivity.5
There is usually a great sense of relief after an endotracheal tube has been placed in a difficult patient, but the problems don’t always end there. Airway emergencies can reoccur after a patient has been extubated. The ASA’s review of closed claims showed that many were related to problems that occurred after the patient was extubated.6 These problems are more common under the following circumstances:
- The patient was a difficult intubation and their airway was traumatized by multiple intubation attempts;
- The patient may have sustained trauma or surgery in the neck and have residual swelling; or
- Access to the patient’s airway could be limited by the presence of cervical collars, traction, or surgery involving the mouth or jaw.
Comprehensive planning prior to extubation can minimize the chance for problems in this area. Consider the factors that may impact ventilation and develop a plan that can be implemented if the patient cannot ventilate. One strategy could involve the placement of an airway exchange catheter. These catheters can be left in place for several hours if needed while the patency of the patient’s airway is being evaluated. More important, they can facilitate intubation if the patient shows signs of distress.
Equipment for the Difficult Intubation
In some cases, the need for equipment other than a conventional laryngoscope will be obvious. When patients cannot be intubated after two attempts using conventional equipment, the associated trauma to the patient should be considered and alternatives should be used. Fortunately, a wide variety of products are available.
|Figure 2. Measuring thyromental distance.|
Before purchasing any equipment, clinicians should keep several considerations in mind. The personal preferences and skill level of the potential users should play a significant role in deciding what is purchased. Having an established skill level with a particular device is extremely valuable in situations where seconds count. Also, it is always better to have more than one device that does basically the same thing, because no single technique works every time. Give consideration to devices that have a high rate of success in novice users. If a new product is being considered and the users have very little experience with it, clinical practice is an absolute requirement, but it may be difficult to come by. A busy operating room or critical care unit is not always an ideal location for practice sessions.
- Intubating oral airways
- Fiberoptic stylets
- Video laryngoscopes
- Flexible fiberoptic scopes
- Supraglottic devices
- Airway exchange catheters
These devices can function as a conventional oral airway but are designed to guide an endotracheal tube toward the glottic opening. They are inexpensive and disposable.
A number of these devices have been introduced to the market in the past few years. There are flexible and semirigid types. Both are inserted through the inside of an endotracheal tube and can significantly improve the operator’s view of the patient’s glottis.
Under most circumstances, these devices provide a good view of the glottis with minimal manipulation of the patient’s head or neck. Even patients with minimal mouth opening don’t seem to present significant problems for these devices. They are expensive, second only to the flexible fiberoptic scope.
These devices offer a number of advantages over a laryngoscope. They can reach the glottic opening from a variety of angles, and the operator can suction secretions throughout the attempt. There are a number of drawbacks as well. They are very expensive and require a significant skill level on the part of the operator. They are limited when it comes to physically displacing tissue. Their working channel is slightly smaller than that of conventional scopes and may become occluded if the secretions are particularly thick. Also, airway visualization is difficult when large amounts of blood are present.
Several types of intubating and nonintubating supraglottic devices are available, and one of each type should be included in any difficult airway kit. They require minimal training, do not require direct visualization of the glottis, and can be inserted even in patients with minimal mouth opening. The nonintubating type does not go through the vocal cords, however, and, thus, cannot offer protection against aspiration. Air leaks can be expected in patients where peak pressures are high.
These devices are used inserted into the endotracheal tube to a depth that is equal to the centimeter mark of the tube and no further. If the tube is defective, the exchange catheter is held in place and the tube is removed. In this position, the exchange catheter acts as a guide to the placement of a new tube.
Practice Makes Perfect
The most expensive equipment and the most complete kits are of little use in the hands of an untrained practitioner. Unfortunately, there are a lot of practitioners who have not had training in managing difficult airways. Advanced cardiac life support (ACLS) and most respiratory care schools do not address this training to any great extent.
|Figure 3. Airway exchange catheter.|
Once the equipment has been assembled, a comprehensive eduction program is essential. This should include some didactic training, but the majority of time should be devoted to hands-on work. Practice on manikins, human patient simulators, cadavers, and even anesthetized volunteers is reported. Some hospitals develop their own in-house programs, but workshops can be found via the Internet. Going to a workshop may not be practical if a large number of people need training. Some providers will come to your facility and conduct training. Whatever methods to provide training are used, it needs to be repeated on a regular basis.
Another element of the training should include some practice following a specific emergency airway management plan. The “plan” could be one of the previously mentioned algorithms. It could also be a locally developed protocol or just a set of guidelines. This process creates a more organized approach and directs practitioners to using the right tool, in the right way, and under the right circumstances.
Mark Grzeskowiak, RRT, is clinical supervisor, adult critical care, Long Beach Memorial Medical Center, Long Beach, Calif. For more information, contact [email protected]
- Davies AE, Kidd D, Stone SP, MacMahon J. Pharyngeal sensation and gag reflex in healthy subjects. Lancet. 1995;345:487-8.
- Chan B, Gaudry P, Grattan-Smith TM, McNeil R. The use of Glasgow Coma Scale in poisoning. J Emerg Med. 1993;11:579-82.
- Hirsch IA, Reagan JO, Sullivan N. Complications of direct laryngoscopy: a prospective analysis. Anesthesiol Rev. 1990;17:34.
- Practice guidelines for management of the difficult airway. A report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 1993;78:597-602.
- Shiga T, Wajima Z, Inoue T, Sakamoto A. Predicting difficult intubation in apparently normal patients: a meta-analysis of bedside screening test performance. Anesthesiology. 2005;103:429-37.
- Caplan RA, Posner KL, Ward RJ, Cheney FW. Adverse respiratory events in anesthesia: a closed claims analysis. Anesthesiology. 1990;72:828-33.