Current Strategies for Airway Management in the Trauma Patient
Part II: Managing Difficult and Failed Airways
Authors: Colin G. Kaide, MD, FACEP, FAAEM, Assistant Professor of Emergency Medicine, Department of Emergency Medicine, The Ohio State University, Columbus; Jason C. Hollingsworth, MD, Emergency Medical Staff Physician, Community Hospital of Indianapolis, Indianapolis, IN.
Peer Reviewer: Perry W. Stafford, MD, FACS, FAAP, FCCM, Chief of Trauma and Surgical Critical Care, Associate Professor of Pediatric Surgery, Department of Pediatric General and Thoracic Surgery, Children’s Hospital of Philadelphia, PA.
This article, the second of two parts, deals with the potentially disastrous situation in which either the patient’s airway presents a substantial challenge or standard intubation methods have failed. There are few more anxiety-provoking events in a practitioner’s clinical practice. The article begins with some algorithms to guide a general approach to difficult airways, followed by a discussion of airway adjuncts and alternatives. The practitioner reading this article is strongly encouraged to read the Manual of Emergency Airway Management by Walls, et al., for an excellent and complete discussion of all aspects of airway management.1— The Editor
Introduction
In general, 1-3% of patients will be difficult to intubate with direct laryngeal visualization. Further, anesthesia literature shows a 0.1-0.4% incidence of intubation failure in patients who were judged apriori as likely to be intubated successfully. Because emergency department (ED) patients generally are sicker and undergo much more cursory and rapid preintubation evaluations, unexpected difficulties are more likely to be encountered. With this understood, the incidence of rescue cricothyrotomy is only 1%, according to early data from the National Emergency Airway Registry.2
Orotracheal intubation employing rapid sequence intubation (RSI) (and in-line cervical stabilization as indicated) is central to airway management. It is the default method of airway control in the trauma and non-trauma patient when both intubation and the use of the bag-valve mask (BVM) are predicted to be successful.
Because the skill set and knowledge base of the individual physician is the best predictor of intubation success, all physicians who are entrusted with the responsibility of airway management should be adequately trained in the assessment and care of the potentially difficult airway. In addition, training in the use of alternative intubation techniques and devices should be mandatory. The importance of developing a "Plan B" for dealing with the difficult or failed airway cannot be underestimated.
Predicting the Difficult Airway
Central to this discussion of the difficult airway are the answers to the following three questions:
- Can this patient be ventilated with a BVM?;
- Will attempts at intubation likely be successful?; and
- Can a cricothyrotomy be performed on this patient if it becomes necessary?
The answers to these questions are based on examination of the airway and neck anatomy as described below. Difficulties with any of these three components can lead to problems in managing the airway.
Predictors of Difficulty with Mask Ventilation. A recent study identified five variables that independently predicted difficult mask ventilation:3
- Presence of a beard;
- Body mass index greater than 26 kg/m2;
- History of regular snoring;
- Edentulousness; and
- Age older than 55.
The presence of any two of these attributes was 72% sensitive and 73% specific for difficult mask ventilation.
Predictors of Difficult Intubation. A thorough evaluation of the patient prior to attempts at laryngoscopy can help to predict a difficult intubation. Walls et al use the "LEMON Law" as a tool to remember what to check to identify a difficult airway during an evaluation.1 (See Table 1.)
Mallampati Classification. The Mallampati classification was developed to correlate a simple visual inspection of the patient’s pharynx with the ability to obtain direct visualization of the larynx. Airways are designated as Class I, II, III, or IV. (See Figure 1.) Mallampati classes roughly correlate with the Cormack and Lehane direct laryngoscopic views, graded as 1, 2, 3, and 4.4,5 Predicted difficulty in obtaining visualization of the cords increases from easy to very difficult as the Mallampati class rises.
Approach to the Difficult Airway
Orotracheal intubation employing RSI is central to airway management. It is the default method of airway control in the trauma and non-trauma patient when both intubation and the use of the BVM are predicted to be successful. When intubation is predicted to be difficult, the use of RSI should not be reflexive, but rather undertaken only when an adequate back-up plan is readily available.
The following approach to the difficult airway assumes that the patient is awake and has been examined, so that the potential difficulty of intubation and mask ventilation may be judged.
BVM Prediction: Difficult. In any circumstance in which a patient appears to be difficult to oxygenate with a mask, the decision to use paralytic agents must be considered carefully. If RSI is to be used, the ability to provide a surgical airway must be assured. After unsuccessful intubation, any patient whose O2 saturation can’t be maintained over 90% with the use of a BVM will need a surgical airway.
Intubation Prediction—Easy; BVM Prediction—Easy. In this circumstance, the initial approach to intubation should be with RSI, utilizing inline stabilization of the cervical spine as indicated by the patient’s injury patterns.
Intubation Prediction—Difficult; BVM Prediction—Easy. This situation potentially can become the "can’t intubate, can oxygenate" scenario. As long as the patient can be adequately oxygenated and ventilated by the BVM and, despite a difficult airway, successful intubation is predicted, an attempt at RSI still is indicated. It is prudent, however, to have a back-up plan readily available.
Intubation Prediction—Difficult; BVM Prediction—Difficult. This represents the potentially disastrous situation of "can’t intubate, can’t oxygenate." Under these circumstances, other options that do not utilize paralytic agents are indicated. These include awake oral intubation and nasotracheal intubation. If the cords can be visualized during the course of an awake intubation attempt using topical anesthetics, it is reasonable either to proceed with the intubation if possible or to revert to the use of RSI.
The Failed Airway
There are many definitions of a failed airway. The one that is favored in the National Airway Course occurs when either of two scenarios develops:6
1) Orotracheal intubation with direct laryngoscopy is unsuccessful after three attempts by an experienced physician. This is the "can’t intubate, can oxygenate" scenario.
2) A single failed attempt at orotracheal intubation with the inability to maintain SpO2 > 90% using a BVM. This is the "can’t intubate, can’t oxygenate" scenario.
If the "can’t intubate, can’t oxygenate" scenario arises, a surgical airway is clearly indicated. If other devices such as an intubating laryngeal mask airway (ILMA) or a Combitube are available, they can be used as temporizing measures in preparation for a more definitive airway. Since these adjuncts do not place a cuffed endotracheal tube (ETT) into the trachea, they do not substitute for definitive management.
Airway Management in the Trauma Patient
There are a few aspects of airway management that are unique to the trauma patient and require special preparations and precautions.
Closed Head Injury. In the closed head injured (CHI) patient, changes in hemodynamics, oxygenation, and ventilation should be minimized in an attempt to maintain adequate cerebral perfusion pressure. Historically, blind nasotracheal intubation was the method of choice for securing the airway in the head-injured patient. In more recent studies, however, orotracheal intubation has been shown to be more rapid and associated with fewer complications.7 Since laryngoscopy causes a marked increase in intracranial pressure (ICP), several measures must be taken in an effort to blunt this response. Modifications in the standard RSI protocol should be performed as follows. (See Table 2.)
The patient should be hyperventilated in an effort to de-crease ICP with a goal PaCO2 of 30-35 mmHg. Administer lidocaine (1.5 mg/kg) 3-5 minutes prior to intubation, as it has been suggested that this can blunt the increase in ICP secondary to laryngeal stimulation.8,9 Beta-blockers (e.g., esmolol) and opiates (e.g., fentanyl) may be given 2-3 minutes prior to intubation to attenuate the sympathetic response in the normotensive patient.10 Etomidate or thiopental are effective induction agents that have not been shown to increase ICP.
Maxillofacial Trauma. Facial trauma can distort normal anatomy significantly. Injuries can range in severity from soot in the airway from a house fire to a gunshot wound entering in the submental area and exiting through the upper cranium. Any such scenario mandates special attention to the type and extent of injury and the current state of respiratory compromise.
In cases in which airway obstruction is either present or imminent, immediate, decisive action is required. Alternatively, some patients may present with some minor respiratory difficulty, but pose a significant risk for rapid deterioration (e.g., severe oral burns, gunshot wounds near the carotid, and intraoral lacerations with hemorrhage). In these patients, a few moments should be taken to plan a strategy to intervene effectively and safely without causing more harm in the process. Expectant management or waiting too long to decide may force the physician to perform a crash cricothyrotomy or an emergent tracheostomy. The latter procedure often is not in the ready repertoire of most emergency physicians.
One of the most feared scenarios in airway management is the patient with maxillofacial trauma and an unsecured airway. As in the management of all difficult airways, proper preparation significantly will increase the chances of successfully securing the airway. The patient should be prepped immediately for a surgical airway in the event of a failed intubation.
There is an associated cervical spine (c-spine) injury in up to 5% of patients with maxillofacial trauma and neurologic injury in up to 36%.11,12 The risk of c-spine injury in patients with maxillofacial trauma, however, is not any higher than the risk associated with other blunt trauma patients with a significant mechanism of injury.13
Of the three major types of facial fractures described by Le Fort, the Le Fort III fracture frequently involves airway compromise secondary to soft tissue obstruction. (See Figure 2.)
If there is no concern for c-spine injury, the patient may be placed in an upright or lateral position to allow blood and secretions to drain.14 In preparing the patient for intubation, it is imperative to check the oropharyngeal anatomy. The patient’s mouth should be opened to assure adequate jaw mobility. This is particularly important in the setting of mandibular fractures due to the high incidence of temporomandibular joint dysfunction. Never attempt nasotracheal intubation in the setting of maxillofacial trauma. RSI is the initial method of choice if the patient passes the LEMON law. If RSI is not possible or is contraindicated, then a surgical airway is indicated.
Direct Airway Trauma. When discussing airway management in the setting of airway trauma, there are two subcategories—direct and penetrating trauma—that require quite different considerations and approaches.
Patients with penetrating trauma usually have more clinical clues to airway involvement than patients with blunt trauma. Important signs or symptoms of airway involvement include dyspnea, cyanosis, subcutaneous emphysema, hoarseness, and air bubbling through the wound site. Penetrating trauma to the neck carries with it a high degree of morbidity and mortality. The overall mortality is as high as 11%,15 with up to 40% requiring emergent intubation.10,16 Tracheobronchial injury occurs in approximately 10-20% of patients with penetrating trauma to the neck.17-20
There are three anatomic zones of the neck. (See Figure 3.) Zone I is located between the clavicles and cricoid cartilage. This area is injured least frequently, but is the most likely to require emergent airway management due to the close proximity to major pulmonary and vascular structures.10 Zone II is located between the cricoid cartilage and the angle of the mandible. This is the most common area of injury but carries the lowest mortality. Finally, Zone III is located between the angle of the mandible and the base of the skull. This zone is the one most commonly associated with vascular and pharyngeal injuries, but is least likely to require emergent airway management.10
There are several important indications for intubation in the setting of penetrating trauma to the neck. They include acute respiratory distress, airway compromise from blood or secretions, extensive subcutaneous emphysema, tracheal shift, and altered mental status.21 Any gunshot wound to the anterior neck also is an indication for early intubation to prevent obstruction from an expanding hematoma.22 Finally, a stab wound to the anterior neck is an indication for early intubation only if there is evidence of vascular or direct airway trauma.23 Although the risk of c-spine injury in the setting of penetrating trauma is less than with blunt trauma, full c-spine immobilization still is recommended.13
Orotracheal intubation with RSI is the technique of choice in securing the airway in the patient with penetrating trauma to the neck.22 Occasionally, administration of paralytics may turn a non-obstructed airway into an obstructed one due to relaxation of an injured airway segment. For this reason, it may be reasonable to do an "awake look" under sedation and topical anesthesia or an awake intubation. Ketamine has been suggested as a good induction agent to use in this setting without an associated paralytic.24
In the setting of severely distorted anatomy or excessive secretions, fiberoptic bronchoscopic intubation may be helpful to assess the degree of tissue injury.17 Occasionally, the entrance wound provides a direct communication between the anterior neck and the trachea. In this case, it may be easier to intubate directly through the wound. Keep in mind, however, that this is only a temporizing measure and ultimately must be converted to a more secure airway. If a surgical airway is required in the presence of an anterior neck hematoma, a tracheostomy should be performed rather than a cricothyroidotomy.
Blunt trauma to the neck frequently is more complicated. Unlike penetrating trauma, blunt trauma carries with it a very high incidence of associated c-spine injuries. Specifically, up to 50% of blunt airway trauma patients have concurrent c-spine injuries.25 Therefore, strict c-spine immobilization precautions need to be maintained while securing the airway. There also is a high incidence of esophageal injuries in patients with laryngotracheal fractures. For this reason, bronchoscopy and esophagoscopy are recommended in any patient with a high clinical suspicion for laryngotracheal injury.14
In terms of securing the airway, there are essentially three initial methods of choice—RSI, awake intubation, and awake fiberoptic intubation. The exception occurs in a laryngeal fracture, in which emergent tracheostomy is the best first maneuver. The American Society of Anesthesiology recommends awake intubation in all patients with possible airway anatomy disruption.25 The concern is that the passage of the ETT may dislodge the severed ends of the larynx, turning a non-obstructed airway into an obstructed one.10,14
Cervical Spine Injury. All trauma patients who come in on a backboard in c-spine precautions should be assumed to have a c-spine injury until proven otherwise. Because airway comes before c-spine, airway management will be performed in the setting of a presumed c-spine injury, so appropriate precautions need to be taken when securing the airway. Keep in mind that 3-6% of initial survivors from major trauma have clinically significant c-spine injuries.26
In uncomplicated trauma, a c-spine may be clinically "cleared" and considered to have low probability of injury if the following five criteria are met: The absence of midline c-spine tenderness; normal alertness; and the absence of intoxication, painful distracting injury, and focal neurologic deficit.27 Patients able to meet these criteria would seem unlikely to require airway support. Multitrauma scenarios in which airway management becomes mandatory often are significantly more complex, and by definition cannot employ the above criteria.
In gunshot wounds to the head (not involving the neck), the distinct absence of concomitant cervical trauma has been documented in multiple reports.28-30 In this scenario, in the absence of other coexisting cervical injury (i.e., falls from significant height, etc.), the c-spine may be considered as low priority.
Historically, attempts to preserve the integrity of the cervical cord led to use of nasotracheal intubation (NTI) as the preferred route of airway access. It was felt that laryngoscopy with oral endotracheal intubation caused too much movement of the c-spine. More recent literature, however, indicates that oral intubation with manual in-line axial head and neck stabilization (MIAS) is as safe or safer than NTI in this setting.31-34
The two initial methods of choice for securing the airway are oral intubation with RSI or awake fiberoptic intubation. When performing RSI, the anterior portion of the collar should be removed to allow for MIAS and cricoid pressure.31 MIAS has been shown to immobilize the c-spine better in the setting of endotracheal intubation than the cervical collar alone.35 The Bullard laryngoscope, a fiberoptic rigid laryngoscope, has been advocated by many to be the intubating method of choice in trauma patients with potential c-spine injuries, since the Bullard does not require alignment of the oral, pharyngeal, and tracheal axes to view the larynx.36-38 The specifics of the Bullard will be discussed below.
Thoracic Trauma. Thoracic trauma may present difficulties when it causes a distortion of the trachea from its normal midline position. This can occur with a tension pneumothorax or with a large intrathoracic hematoma. Occasionally, a large pneumothorax can cause significant subcutaneous emphysema tracking into the neck, which can interfere with the ability to identify the trachea and/or cricothyroid membrane.
Pneumothorax, hemothorax, or significant trauma to the lung (pulmonary contusion) can inhibit the practitioner’s ability to adequately preoxygenate the patient prior to the intubation. If the patient’s airway can wait, it may be very reasonable to reverse a collapsed lung or evacuate a hemothorax first so as to maximize the preoxygenation phase of the intubation.
Burns. The key principle in the treatment of burn patients with airway involvement is aggressive airway management. Because upper airway edema is progressive during the 24-36 hours following the burn, it is advisable to secure an airway sooner rather than later. Some strong indications for intubation include: stridor or hoarseness; known inhalation of toxic fumes; carbonaceous material in the oropharynx or nares; or increased work of breathing.
Smoke inhalation in burn patients accounts for nearly half of all deaths related to fire.39 Further, the possibility of carbon monoxide poisoning should be given consideration. Since a pulse oximeter is unable to differentiate between oxyhemoglobin and carboxyhemoglobin, a blood gas sample needs to be analyzed for carboxyhemoglobin.
Standard oral endotracheal intubation with RSI is the initial method of choice to secure the airway when no obvious obstruction is visualized. If in doubt, "an awake look" should be performed under sedation and topical anesthetics. If no problems are seen, one can proceed with RSI. Because of the incidence of upper airway edema, however, there should be low threshold for proceeding to fiberoptic intubation or cricothyrotomy.
Alternative Intubation Techniques and Airway Adjuncts
As previously discussed, the primary intubation technique in the trauma patient is oral endotracheal with RSI. In some circumstances, however, this is either not possible or contraindicated (e.g., closed tracheal disruption, known allergy to RSI medications, or predicted difficult intubation). It also is important to have back-up methods of securing the airway. There are many alternative intubation techniques and airway adjuncts. Only those that have been shown to be safe and effective in trauma patients will be discussed.
Awake Intubation. An awake intubation is performed on patients who potentially may be difficult to intubate. Unlike the serial sedation of the past (used to "soften the patient up"), this procedure utilizes sedation in combination with topical anesthetics to facilitate laryngoscopy while intentionally maintaining the patient’s airway reflexes and spontaneous respiration. Topical anesthetics can be administered by nebulization or by direct application to the pharynx. (See Table 3.)
This technique can be implemented to obtain a close look at the glottis to assure the ability to visualize the cords (an "awake look"). When the cords are visualized, an attempt to pass the tube can be made or the blade can be withdrawn and formal RSI then can be used.
A few minutes before the intubation, nebulized lidocaine may be delivered to the patient to provide pharyngeal/laryngeal anesthesia. This can be supplemented further by cetacaine or topical lidocaine sprayed directly into the posterior pharynx. The patient then can receive the sedative of choice titrated to effect, much like in a conscious-sedation procedure.
Nasotracheal Intubation. NTI was once the technique of choice in establishing an airway in a trauma patient. Today, however, it rarely is indicated in the acute management of trauma patients secondary to the increased time requirement, lower success rate, and increased risk of severe bleeding when compared to oral endotracheal intubation.40 In fact, it is indicated only if clear contraindication exists to RSI and other airway modalities are not available. Absolute contraindications include coagulopathy, mid-face fractures, or basilar skull fractures.41
Retrograde Intubation. This is an excellent technique to utilize in the setting of maxillofacial trauma, particularly with significant upper airway bleeding or limited jaw opening, as well as with unstable c-spine injuries. It has a unique niche in the management of the trauma airway and has been demonstrated to be a safe and rapid technique in trauma patients.42 The only true contraindication is an apneic patient who cannot be adequately oxygenated or ventilated.
The cricothyroid membrane first is identified and the inferior aspect of the membrane is punctured with a needle-directed cephalad. When air is aspirated, a guidewire is inserted and advanced retrograde until the proximal end is controlled through the mouth. The needle is removed, leaving only the guidewire in place. A plastic sheath is passed antegrade over the wire until resistance is met at the anterior laryngeal wall. The ETT then is passed antegrade over the sheath through the vocal cords and up against the cricothyroid membrane. The wire and sheath are removed simultaneously through the mouth.
The Cook retrograde intubation set, which contains a sheath, is the set-up of choice; however, an 18-gauge needle, an 80-cm J-tipped guidewire, and hemostats can be used. Triple-lumen central line placement kits contain the needles, syringes, and guidewire needed to perform the procedure. Swan-Ganz sheath introducer kits, however, contain a guidewire that often is too short. (See Figure 4 A-D.)
Lighted Stylet. This technique involves the blind placement of an ETT containing a battery-operated, lighted stylet that transilluminates the anterior soft tissues of the neck. The technique takes advantage of the anterior location of the trachea in relation to the esophagus. The ETT is bent at a 90° angle just proximal to the cuff, so that it resembles a hockey stick. The lightwand is turned on and the ETT lightwand unit (ETT-LW) is advanced blindly into the posterior oropharynx. The device is rocked back and forth in the midline in an imaginary arc. When the ETT-LW has entered the glottic opening, a well-circumscribed glow can be seen in the anterior neck, slightly below the laryngeal prominence.43 A faint glow above the laryngeal prominence indicates that the tip is in the vallecula; a dim light located on the side of the neck indicates that the tip is in the piriform sinus, and a very dim light in the anterior neck indicates that the tip is in the esophagus. Once tracheal intubation is confirmed as described above, the stylet is retracted approximately 10 cm and the ETT-LW is advanced until the glow begins to disappear at the sternal notch, indicating that the tip of the ETT is approximately 5 cm above the carina.44 The locking clamp then is released and the lightwand removed while stabilizing the ETT.
Clinical scenarios where the lightwand is useful include patients with difficult airways in whom direct laryngoscopy has failed, and in patients with copious upper airway bleeding or secretions. Patients with anterior neck soft-tissue trauma or morbidly obese patients are relative contraindications due to inadequate transillumination of the anterior neck. Prior to the invention of the trachlight with a brighter light source, its use was limited in the ED by the need to dim overhead lights. Dimming the ambient lights no longer is recommended.
Bullard Laryngoscope. The Bullard laryngoscope is an indirect fiberoptic, rigid laryngoscope. The blade is wider and longer than conventional laryngoscopes and the end of the blade is able to retract the epiglottis. The independently styletted ETT is side-loaded onto the laryngoscope. Because the Bullard utilizes indirect laryngoscopy, the oral, pharyngeal, and tracheal axes do not need to be aligned to visualize the larynx. This translates into less c-spine movement. For this reason, many consider it to be superior to conventional laryngoscopy in patients with potential c-spine injury.36,45 In a study conducted by Watts et al comparing Bullard and Macintosh laryngoscopes, the degree of c-spine extension was significantly less with the Bullard.38
The Bullard laryngoscope is an excellent tool for endotracheal intubation in the c-spine injured patient; however, it is not without its disadvantages. Because the blade is larger than conventional laryngoscopes, manipulation is more cumbersome and this can translate into a longer intubation time.38
Endotracheal Tube Introducer. The ETT introducer is a 60 cm, semirigid rod, approximately 5 mm in diameter. It is elastic and flexible, with the distal 2 cm angled upward 36°. This type of device was first described in 1949 and also is known as a gum elastic bougie or an Eschmann tracheal tube introducer.46,47 A less expensive plastic version called the Flex-Guide ET Tube Introducer (GreenField Medical Sourcing, Inc., Northborough, MA) also is available.47
These devices, which have become very popular in Europe for difficult intubations, are designed to enter the trachea blindly and allow an ETT to be guided into position. In studies with patients with simulated c-spine injuries and a Mallampati score of 3 or less, successful first attempt intubations are reported at 96-100%, compared to significantly lower rates with a traditional stylet.48,49
While the jaw and tongue are lifted by a laryngoscope, the device is placed blindly into the pharynx with the introducer aligned in the midline and the angled tip pointed upward. The angle of the tip facilitates placement under the epiglottis and through the cords. When tracheal placement is achieved, the tip of the introducer is advanced over the tracheal rings, creating a "washboard" sensation. When it is fully inserted, the tip should impact on the carina and provide resistance to further insertion. When in place, the introducer can be withdrawn until a black mark on the device is aligned with the lip. At this depth (37 cm) the device is in far enough to be located beyond the cords. An ETT then can be placed over the introducer and guided into the trachea, with subsequent removal of the device through the ETT. This device may have significant utility in trauma patients for whom limited neck mobility may be tolerated.
Laryngeal Mask Airway and the Intubating Laryngeal Mask Airway. The laryngeal mask airway (LMA) is an ETT with an attached silicone rubber collar that covers the supraglottic area, thereby enclosing the larynx. The device originally was invented by Brain in the early 1980s and subsequently has undergone several modifications.50 Today, two forms are in widespread use: the classic LMA and the intubating LMA (ILMA). Both are relatively easy to use and serve as quick rescue devices for patients who can’t be intubated by conventional means.
The classic LMA comes in sizes for adolescents, and for small, average-size, and large adults. There also are four weight-based sizes (1-2.5) designed for children. Before inserting the LMA, apply water-soluble lubricant to the sides of the collar. When inserting the LMA, place the tip of the cuff against the patient’s hard palate and advance it along the natural curve of the hypopharynx until resistance is met. The collar then is inflated with the size-appropriate amount of air.
In the ILMA there are two important modifications to the classic design, which allow for the placement of an ETT. First, there is a single stiff bar vertically oriented across the mask aperture that lifts the epiglottis away from the path of the ETT. Second, there is a ramp within the barrel-mask junction designed to direct the ETT into the trachea. The ILMA also is equipped with a steel handle that facilitates its insertion, manipulation, and removal to minimize c-spine movement.51 Success rates of intubation with the ILMA were comparable to those achieved with a fiberoptic scope in patients with anticipated difficult intubation.52 The ILMA only comes in adult sizes equivalent to sizes 3, 4, and 5 found in the classic LMA.53-55
The ILMA is inserted in the same manner as the classic LMA but with the assistance of the metal handle. Once in place with the collar inflated, the ETT (up to size 8.0) is placed into the metal tube of the ILMA and advanced into the trachea. The ILMA then can be either left in place or withdrawn over the ETT.
The primary advantage of the LMA is that it is quick and easy to use with minimal training. Keep in mind, however, that the LMA is not a substitute for a cuffed ETT. It is only a bridge until the placement of a more definitive airway. The LMA does not prevent aspiration, and it is unable to overcome obstruction at the level of the larynx.
Esophageal-Tracheal Combitube. The Combitube is a dual lumen tube with a cuffed esophageal lumen and a cuffed tracheal lumen. The esophageal lumen is open to the upper airway and is closed at the distal end. The tracheal lumen is open only at the distal end. A large, proximal balloon seals the oropharyngeal airway when inflated. A small, distal balloon seals the esophagus or trachea, depending on the position of the Combitube.
The Combitube is inserted blindly along the posterior oropharynx until the printed rings are aligned with the teeth. The proximal balloon is inflated, followed by the distal balloon. Ventilation should be started through the longer esophageal lumen. This will result in tracheal ventilation 90% of the time. Check tube placement by auscultating over the stomach and both axilla. If no breath sounds are present, the tube is in the trachea and the shorter tracheal tube should be used for ventilation.
Like the LMA, the Combitube is a rescue airway device and does not take the place of a cuffed ETT. It also is very easy to place, but does not protect the airway against aspiration. Its role in trauma patients has been defined as a rescue device in patients who cannot be expeditiously intubated by conventional means.56
Flexible Fiberoptic Bronchoscope. Although the fiberoptic bronchoscope provides excellent visualization of the upper airway anatomy during intubation, it rarely is used by emergency physicians in the management of the trauma airway. Bronchoscopy requires a level of skill that most emergency physicians do not attain in their limited experience with this instrument. In most cases, the use of bronchoscopy is reserved for our ear-nose-throat and anesthesiology colleagues. Nonetheless, there are certain well-defined indications for fiberoptic bronchoscopy in airway management. Examples include the awake patient with a known difficult airway, the patient with an unstable cervical spine injury, the patient with upper airway burns, and finally the patient with an expanding neck hematoma.
Because intubation over a fiberoptic bronchoscope requires more time and technical skill than conventional laryngoscopy, it is not recommended in the setting of penetrating neck trauma.16 An explanation of the procedural details is beyond the scope of this text.
Surgical Airway
With all of the advances in adjunctive airway techniques, cricothyrotomy is performed infrequently. The National Emergency Airway Registry reported a 1% ED cricothyrotomy rate in more than 6000 ED intubations.57 Due to the infrequent need for surgical airways, physicians may lack the experience and skill needed to practice this technique safely and efficiently.58,59 For this reason, it is essential for the emergency physician to be familiar with the anatomy of the neck and the steps required to perform the procedure.
There are several indications for cricothyrotomy, the most common of which is the inability to intubate the trachea in a patient who cannot be oxygenated or ventilated. Another significant indication includes trauma to the face severe enough to significantly distort airway anatomy.
Cricothyrotomy is contraindicated in cases of laryngeal fracture and in the setting of complete laryngotracheal separation, as the skin may be the only tissue holding the proximal trachea in the neck.60-62 Owing to the small size of the cricothyroid membrane, the procedure also is contraindicated in children younger than 10-12 years of age, in whom needle cricothyrotomy is the preferred technique. (See Table 4.)
There are three main techniques that currently are practiced: the standard method; the rapid four-step technique; and the wire-guided technique.
The first step in any cricothrotomy technique is to correctly identify the landmarks. The thyroid cartilage generally is the most prominent structure in the anterior neck (Adam’s apple). The cricoid cartilage lies inferior to the thryoid cartilage, separated by the cricothryoid membrane.
After the anatomy is identified, a 3-4 cm vertical skin incision should be made over the cricothyroid space while holding the thyroid cartilage with the non-dominant hand. A tracheal hook is introduced into the cricothyroid space and traction is applied in a cephalad direction. A transverse incision is made in the cricothyroid membrane and the tract is dilated with a dilator or scalpel handle. A Shiley cuffed tracheostomy tube then is inserted in a posterior and caudal direction. The balloon can be inflated and the introducer removed. A 6.0 ETT can be used if a Shiley is not available. (See Figure 5 A-E.)
Brofeld designed the rapid four-step technique in an effort to simplify the procedure and decrease the time involved.63 In this technique, the cricothyroid membrane is identified by palpation. A horizontal stab incision then is made through both the skin and cricothyroid membrane with a No. 20 scalpel blade. The larynx is stabilized with a tracheal hook pulling caudal traction on the inferior aspect of the cricoid cartilage.
A Shiley tracheal tube is introduced into the trachea as described above. This technique has been shown to be much faster than the standard method in a cadaver study;64 however, there are some concerns regarding an increased risk of laryngeal injury.65 Davis et al showed no increased risk of laryngeal injury when compared to the standard method when using a "Bair claw," as opposed to a tracheal hook, to retract the cricoid membrane.66
The wire-guided technique utilizes an approach similar to the Seldinger technique used to obtain central venous access. In this technique, the neck structures are identified and a vertical skin incision is made over the cricothyroid membrane. An 18-gauge needle attached to a syringe is directed inferiorly through the cricothyroid membrane. Aspiration of air confirms placement of the needle in the trachea. The syringe is removed and the guidewire is inserted through the needle. The needle then is removed and the Shiley ETT with dilator is inserted over the wire. Finally, the wire and dilator are removed, leaving the airway in place in the trachea. Although not significantly different in terms of efficiency or rate of complications, it was shown to be preferred over the standard technique.66
Conclusion
In this day and age, airway management by the emergency physician has risen to a degree of sophistication well beyond that practiced by any other specialty except anesthesia. It is the responsibility of any physician who practices emergency medicine to obtain and maintain the requisite skills necessary to practice airway management at this level.
At the core of airway management in all patients is a good understanding of when and how to intervene and provide definitive airway control. Although the setting and injury patterns can be dramatic, management of the trauma airway involves the same basic skills required for any other difficult airway. The well-prepared physician should possess sound, basic intubation skills and be intimately familiar with the various induction and paralytic agents. He or she should have a working knowledge of some of the common airway adjuncts and the requisite skills to create a surgical airway. Finally, the physician should be aware of, and have a plan to deal with, the potential pitfalls and disasters that can occur while taking control of a patient’s vital functions.
References
1. Walls RM. Confirmation of endotracheal tube placement. In: Walls RM, Luten RC, Murphy MF, et al, eds. Manual of Emergency Airway Management. 1st ed. Philadelphia; Lippincott, Williams & Wilkins: 2000.
2. Murphy MF, Walls RM. The difficult and failed airway. In: Walls RM, Luten RC, Murphy MF, et al, eds. Manual of Emergency Airway Management. 1st ed. Philadelphia; Lippincott, Williams & Wilkins: 2000.
3. Langeron O, Masso E, Huraux C, et al. Prediction of difficult mask ventilation. Anesthesiology 2000;92:1229-1236.
4. Mallampati SR, Gatt SP, Gugino LD, et al. A clinical sign to predict difficult intubation: A prospective study. Can Anesth Soc J 1985; 32:429.
5. Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia 1984;39:1105-1111.
6. Walls RM. The emergency airway algorithms. In: Walls RM, Luten RC, Murphy MF, et al, eds. Manual of Emergency Airway Management. 1st ed. Philadelphia: Lippincott, Williams & Wilkins: 2000.
7. Talucci RC, Shaikh KA, Schwab CW. Rapid sequence induction with orotracheal intubation in the multiply injured patient. Am Surg 1998;54:185-187.
8. Bedford RF, Winn HR, Tyson G, et al. Lidocaine prevents increased ICP after endotracheal intubation. In: Shulman K, Mamorou A, Miller JD, et al, eds. Intracranial Pressure IV. Berlin: Springer; 1980:595-598.
9. Hamill JF, Bedford RF, Weaver DC, et al. Lidocaine before endotracheal intubation: Intravenous or laryngotracheal? Anesthesiology 1981;55:578-581.
10. Cicala RS. The traumatized airway. In: Benumof JL, ed. Airway Management: Principles and Practice. St. Louis: Mosby-Year Book; 1996:736-759.
11. Conforti PJ, Haug RH, Likavec M. Management of closed head injury in the patient with maxillofacial trauma. J Oral Maxillofac Surg 1993;51:298.
12. Hills MW, Eeane SA. Head injury and facial injury: Is there an increased risk of cervical spine injury? J Trauma 1993;34:549.
13. Ivy, ME. Addressing the myths of cervical spine injury management. Am J Emerg Med 1997;15:591-595.
14. Murphy MT, Latham P. Anesthetic management of trauma to the airway. Anesth News 1996;43.
15. Asensio JA, Valenziano CP, Falcone RE, et al. Management of penetrating neck injuries: The controversy surrounding Zone II injuries. Surg Clin North Am 1991;71:267-296.
16. Angood PB, Attia EL, Brown RA, et al. Extrinsic civilian trauma to the larynx and cervical trachea: Important predictors of long-term morbidity. J Trauma 1986;26:869.
17. Gussack GS, Jurkovick GJ, Luterman A. Laryngotracheal trauma: A protocol approach to a rare injury. Laryngoscope 1986;96:660-665.
18. McConnell DB, Trunkey DD. Management of penetrating trauma to the neck. Adv Surg 1994;27:97-127.
19. Thompson JN, Strausbaugh PL, Koufman JA, et al. Penetrating injuries of the larynx. South Med J 1984;77:41-45.
20. Eggen JT, Jorden RC. Airway management, penetrating neck trauma. J Emerg Med 1993;11:381-385.
21. Walls RM. Contemporary issues in trauma: Management of the difficult airway in the trauma patient. Emerg Med Clin North Am 1998;16: 45-62.
22. Walls RM, Wolfe R, Rosen P. Fools rush in? Airway management in penetrating neck trauma [editorial]. J Emerg Med 1993;11:479-482.
23. Capan LM, Miller SM Turndorf H. Management of neck injuries. In: Caplan LM, Miller SM, Turndorf H, eds. Trauma Anesthesia and Intensive Care. Philadelphia: JB Lippincott; 1991:415-418.
24. Sinclair D, Schwartz M, Gruss J, et al. A retrospective review of the relationship between facial fractures, head injuries, and cervical spine injuries. J Emerg Med 1988;6:109-112.
25. American Society of Anesthesiologists. 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.
26. Hoffman JR, Mower WR, Wolfson AB, et al. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. National Emergency X-Radiography Utilization Study Group (NEXUS). N Engl J Med 2000;343:94-99.
27. Kaups KL, Davis JW. Patients with gunshot wounds to the head do not require cervical spine immobilization and evaluation. J Trauma 1998;44:865.
28. Kennedy FR, Gonzales P, Beitler A, et al. Incidence of cervical spine injury in patients with gunshot wounds to the head. South Med J 1994;87:621-623.
29. Lanoix R, Gupta R, Leak L, et al. C-spine injury associated with gunshot wounds to the head: Retrospective study and literature review. J Trauma 2000;49:860-863.
30. Criswell JC, Parr MJ, Nolan JP. Emergency airway management in patients with cervical spine injuries. Anesthesia 1994;49:900.
31. Holley J, Jorden R. Airway management in patients with unstable cervical spine fractures. Ann Emerg Med 1989;18:237.
32. Rhee KJ, Green W, Holcroft JW, et al. Oral intubation in the multiply injured patient: The risk of exacerbating spinal cord damage. Ann Emerg Med 1990;19:511.
33. Wright SW, Robinson GG. Cervical spine injuries in blunt trauma patients requiring emergent endotracheal intubation. Am J Emerg Med 1992;10:104-109.
34. Majernick TG, Bieniek R, Houston JB, et al. Cervical spine movement during endotracheal intubation. Ann Emerg Med 1986;15: 417-426.
35. Abrams KJ, Desai N, Datsnelson T. Bullard laryngoscopy for trauma airway management in suspected cervical spine injuries. Anesth Analg 1992;74:619-623.
36. Gorbrek MS. Management of the challenging airway with the Bullard laryngoscope. J Clin Anesth 1991;3:473-477.
37. Watts AD, Gelb AW, Bach DB, et al. Comparison of the Bullard and Macintosh laryngoscopes for endotracheal intubation of patients with a potential cervical spine injury. Anesthesiology 1997;87: 1335-1342.
38. Thierback AR, Lipp MD. Airway management in trauma patients. Anesth Clin North Am 1999;17:63-81.
39. Dauphinee K. Nasotracheal intubation. Emer Med Clin North Am 1988;6:715.
40. Barriot P, Riou B. Retrograte technique for tracheal intubation in trauma patients. Crit Care Med 1988;16:712-714.
41. Walls RM. Rapid sequence intubation in head trauma. Ann Emerg Med 1993;22:1008-1013.
42. Hung OR, Murphy M. Lightwands, lighted stylets, and blind techniques of intubation. ACNA 1995;13:477-489.
43. Stewart RD, Larosee A, Kaplan RM, et al. Correct positioning of an endotracheal tube using a flexible lighted stylet. Crit Care Med 1990;18:97-99.
44. Hastings RH, Vigil AC, Hanna R, et al. Cervical spine movement during laryngoscopy with the Bullard, Macintosh, and Miller laryngoscopes. Anesthesiology 1995;82:859-869.
45. MacIntosh RR. An aid to oral intubation. BMJ 1949;1:28.
46. Moscati R, Dietrich J, Christiansen G, et al. Endotracheal tube introducer for failed intubations: A variant of the gum elastic bougie. Ann Emerg Med 2000;36:1, 52-56.
47. Gataure PS, Vaughan RS, Latto IP. Simulated difficult intubation: Comparison of the gum elastic bougie and the stylet. Anesthesia 1996;51:935-938.
48. Nolan JP, Wilson ME. Orotracheal intubation in patients with potential cervical spine injuries: An indication for the gum elastic bougie. Anesthesia 1993;48:630-633.
49. Brain AI. The development of the laryngeal mask—A brief history of the invention, early clinical studies, and experimental work from which the laryngeal mask evolved. Eur J Anaesthesiol 1991;4:5-17.
50. Rosenblatt WH, Murphy M. The intubating laryngeal mask: Use of a new ventilating-intubating device in the emergency department. Ann Emerg Med 1999;33:234-238.
51. Brain AI, Berghese C, Addy EV, et al. The intubating laryngeal mask: I. Development of a new device for intubation of the trachea. Br J Anaesth 1997;79:703.
52. Langeron O, Semjen F, Bourgain JL, et al. Comparison of the intubating laryngeal mask airway with the fiberoptic intubation in anticipated difficult airway management. Anesthesiology 2001;94:968-972.
53. Brain AI, Berghese C, Addy EV, et al. The intubating larygneal mask: II. A preliminary clinical report of a new means for intubating the trachea. Br J Anaesth 1997;79:704-709.
54. Kapila A, Addy EV, Berghese C, et al. The intubating laryngeal mask airway: An initial assessment of performance. Br J Anaesth 1997;79:710-713.
55. Blostein PA. Failed rapid sequence intubation in trauma patients: Esophageal tracheal Combitube is a useful adjunct. J Trauma 1998; 44:534-537.
56. Bainton CR. Cricothyrotomy. Int Anesth Clin 1994;32:95-108.
57. Appendix 1. In: Walls RM, Luten RC, Murphy MF, et al., eds. Manual of Emergency Airway Management. 1st ed. Philadelphia: Lippincott, Williams & Wilkins; 2000.
58. Chang RS, Hamilton RJ, Carter WA. Declining rate of cricothyrotomy in trauma patients with an emergency medicine residency: Implications for skill training. Acad Emerg Med 1998;5:247-251.
59. Bent, JP, Silver JR, Porubsky ES. Acute laryngeal trauma: A review of 77 patients. Otolaryngol Head Neck Surg 1993;109:441-449.
60. Einarsson, O, Rochester CC, Rosenbaum S. Airway management in respiratory emergencies. Clin Chest Med 1984;15:13-34.
61. Grande CM, Barton CR, Stene JK. Appropriate techniques for airway management for emergency patients with suspected spinal cord injury. Anesth Analg 1998;67:714-715.
62. Brofeld BT, Panacek EA, Richards JR. An easy cricothyrotomy approach: The rapid 4-step technique. Acad Emerg Med 1996;3: 1060-1063.
63. Holmes JF, Panacek EA, Sackles JC, et al. Comparison of two cricothyrotomy techniques: Standard methods verses rapid 4-step technique. Ann Emerg Med 1998;32:442-446.
64. Davis DP, Bramwell KJ, Vilke GM, et al. Cricothyrotomy technique: Standard versus rapid 4-step technique. J Emerg Med 1999;17:17-21.
65. Davis DP, Bramwell KJ, Hamilton RS, et al. Safety and efficacy of the rapid 4-step technique for cricothyrotomy using a Bair claw. J Emerg Med 2000;19:125-129.
66. Chan TC, Vilke GM, Bramwell KJ, et al. Comparison of wire-guided cricothyrotomy versus standard surgical cricothyrotomy technique. J Emerg Med 1999;17:957-962.
This article, the second of two parts, deals with the potentially disastrous situation in which either the patients airway presents a substantial challenge or standard intubation methods have failed.
Subscribe Now for Access
You have reached your article limit for the month. We hope you found our articles both enjoyable and insightful. For information on new subscriptions, product trials, alternative billing arrangements or group and site discounts please call 800-688-2421. We look forward to having you as a long-term member of the Relias Media community.