Patients with difficult airways should be identified before the induction of anesthesia and intubation so that proper planning and communication between the anesthesiologist and the surgeon can be coordinated. A difficult airway is defined as a situation in which a conventionally trained anesthesiologist experiences difficulty with mask ventilation, endotracheal intubation, or both. In addition, the physician should be prepared for a potentially difficult airway or possible airway loss if both anesthesia induction and intubation are difficult. Both of these situations can be managed with a number of nonsurgical airway management techniques.
The first and most important task in nonsurgical airway management is to administer oxygen to relieve hypoxia. As the airway obstruction worsens, the physician may have to mask, ventilate, and provide a chin lift and jaw thrust to maintain a patent airway until a more definitive airway can be established. A helium–oxygen mixture of 80% helium to 20% oxygen can be used in some cases to improve ventilation temporarily until definitive control of the airway can be achieved. This mixture, known as heliox, depends on the decreased density of helium to deliver oxygen past the obstructing airway lesions.
Topical Decongestants and Steroids
Adjunctive medical therapy can be used to decrease upper airway obstruction if there is a component of soft tissue edema. Racemic epinephrine and epinephrine aerosols act as topical decongestants and can be given to try to decrease the edema. However, the effect is short in duration, and they may cause a rebound effect if used repeatedly. Consequently, their use is limited to the inpatient setting. The use of steroids in relieving upper airway obstruction can also be helpful, especially in cases in which edema or inflammation is present (eg, angioedema, croup, and adult supraglottitis). A suggested treatment is to administer methylprednisolone sodium succinate (125 mg IV) as a first dose and then continue with dexamethasone (8 mg IV every 8 hours) for several doses; methylprednisolone succinate has a more rapid onset of action than dexamethasone.
Oropharyngeal and Nasopharyngeal Airways
Oropharyngeal and nasopharyngeal airways are adjuncts to airway support that can be helpful in certain cases. For example, patients emerging from anesthesia or suffering from an altered mental state can have their airways supported with these devices until their mental status improves. Oropharyngeal airways prevent obstruction caused by a relaxed and prolapsed tongue. However, an incorrectly placed oropharyngeal airway can itself cause airway obstruction by pushing the tongue posteriorly into the hypopharynx. If placed in a patient who is still under light anesthesia, coughing and laryngospasm can occur. The traumatic insertion of nasal or nasopharyngeal airways can cause bleeding.
The definitive nonsurgical control of the airway is via translaryngeal intubation. This procedure should be considered the preferred method of establishing control of the airway in most cases, provided the patient's condition is not so dire that an immediate airway is required, or in situations in which intubation is contraindicated (eg, laryngeal trauma or an obstructing tumor that makes intubation difficult). It is extremely important that a good airway history be obtained and a thorough examination be performed whenever possible before inducing anesthesia and performing an intubation.
Jackson Sliding Laryngoscope
A unique instrument familiar to otolaryngology surgeons is the Jackson sliding laryngoscope (Figure 38–1). This laryngoscope has better leverage and lighting compared with the anesthesiologist's blades; the design of the laryngoscope makes it easier to manipulate past obstructing lesions or edematous soft tissue and suction can be used concurrently. Once the glottis is identified, an endotracheal tube is passed into the trachea and the laryngoscope's floor can be slid out to facilitate removal of the laryngoscope. Frequently, the difficult airway can be managed with this technique.
(A) Side view of a sliding Jackson laryngoscope. (B) View along the aperture. The floor can be slid out after insertion of an endotracheal tube.
Guided Endotracheal Intubation
Guided endotracheal intubation using a flexible fiberscope is an excellent technique for both routine and difficult airways. Placing an endotracheal tube with a fiberscope tube is particularly useful for an intubation in an awake, spontaneously breathing patient with a known or suspected difficult airway. Fiberoptic endotracheal intubations can be performed either via a nasal or an oral route. Once the route is chosen and anesthesia is achieved (topical or general), the endoscope is passed through the endotracheal tube, through the mouth or nose, and through the larynx into the trachea. The endotracheal tube is then advanced over the endoscope and into the trachea, using the endoscope as a “guidewire.” The endoscope is withdrawn after confirming the correct positioning of the endotracheal tube. Flexible fiberoptic intubation has limitations as well. Minimal trauma to these endoscopes may damage the delicate optics and distort the visual field. Bleeding and secretions can obscure the view and make visualization of the glottis extremely difficult. This technique may also be difficult in the uncooperative patient or in patients with inadequate topical anesthesia. Finally, introduction of the endoscope may actually cause complete airway obstruction in patients with severe intrinsic or extrinsic compression of the laryngeal or tracheal airways.
The laryngeal mask airway (LMA) is useful for establishing the airway in both routine elective cases and many emergency situations involving difficult airways. The LMA can be considered a hybrid between an endotracheal tube and a face mask (Figure 38–2). It can easily be inserted blindly into the hypopharynx; insertion is complete when resistance is felt. No neck movement or laryngoscopy is required. Once the mask is inflated, it fills the hypopharynx and covers the laryngeal inlet. Due to the LMA's size and shape, it is not possible to pass it into the esophagus.
Several series report excellent success rates of 95–99%. Other advantages of the LMA include its simplicity in learning and use, fewer postoperative sore throats and coughing, and less potential for laryngeal injuries. These features also make the LMA an excellent instrument to use in many emergency situations involving the airway. Because this device can be inserted quickly and blindly, it has the potential to provide lifesaving ventilation while a more definitive airway is established. A flexible fiberoptic endoscope can also be passed through the mask's open slit into the trachea, and an endotracheal tube can be passed over the endoscope. Since the LMA does not completely separate the airway from the esophagus, the greatest risk in using this device is pulmonary aspiration of regurgitated stomach contents. Contraindications to using this airway include patients with full stomachs or hiatal hernias, obesity, and emergency and abdominal surgeries. The need for controlled ventilation and prone or lateral positions are strong relative contraindications for elective use of this device. Understandably, if the mouth cannot be opened, the LMA is not useful.
Other Nonsurgical Measures
Less common instruments and techniques used in difficult airway situations include the esophageal Combitube, light wand, and the Bullard laryngoscope. The esophagotracheal Combitube is an emergency airway management device for patients requiring rapid airway control. In many cases, this device can provide lifesaving emergency ventilation and oxygenation until a surgical airway can be established. The esophagotracheal Combitube is a double-lumen tube with an open “tracheal” cannula and a blocked distal “esophageal” end, which has ventilating side holes located proximally (Figure 38–3). This device is also blindly inserted, and the upper and lower balloons inflated. Because of its design, the esophagotracheal Combitube can effectively ventilate the upper airway regardless of whether it is placed into the trachea or into the esophagus. If the Combitube tip is in the esophagus, ventilation is achieved through the proximal side ventilation holes of the esophageal port. If this device is inserted into the trachea during the blind intubation, ventilation is accomplished conventionally through the tracheal port. Because of its relatively large size, this Combitube is contraindicated in pediatric and very small adult patients. It should be used with caution in patients with upper esophageal pathology, upper airway tumors, or other compressive lesions of the hypopharynx, larynx, or trachea. Finally, laryngospasm and laryngotracheal foreign bodies can impair ventilation if this device is inserted into the esophagus.
Esophagotracheal Combitube. The diagram depicts the esophagotracheal Combitube in the esophagus. Ventilation is accomplished via the proximal side ports. (Image used with permission from Nellcor Puritan Bennett LLC, Boulder CO.)
When endotracheal intubation is not feasible, a surgical airway must be obtained. The two basic surgical techniques to obtain an airway are cricothyroidotomy and tracheotomy. The terms tracheotomy and tracheostomy are often used interchangeably in error. A tracheotomy is generally described as a procedure that involves opening the trachea. A tracheostomy is a procedure that exteriorizes the trachea to the cervical skin, resulting in a more permanent tracheal cutaneous fistula; therefore, the term tracheostomy should be reserved for these particular procedures.
The indications for establishing an urgent surgical airway include the following: (1) severe maxillofacial trauma in which injuries make the airway inaccessible for translaryngeal intubation, (2) significant laryngeal trauma in which intubation may potentially cause more damage, (3) excessive hemorrhage or emesis obscuring landmarks required for successful intubation, (4) cervical spine injury with vocal cords that are difficult to visualize, and (5) failed translaryngeal intubation. In emergency situations, cricothyroidotomy is generally considered the procedure of choice because it is fast and simple to perform and it requires very few instruments. However, a tracheotomy can also be performed urgently. It is technically more difficult, bloody, and dangerous compared with elective tracheotomy or cricothyroidotomy. There are rare circumstances in which an emergent tracheotomy is preferred over a cricothyroidotomy, such as true subglottic obstruction (eg, subglottic carcinoma, or large thyroid tumors). Cricothyroidotomy should also be avoided in children because the cricoid cartilage is the narrowest portion of their airway.
The primary objective of a tracheotomy is to provide a secure airway. The indications for performing a tracheotomy include: (1) bypassing an upper airway obstruction, (2) providing a means for assisting mechanical ventilation (ie, chronic ventilator dependence), (3) enabling more efficient pulmonary hygiene, (4) temporarily securing an airway in patients undergoing major head and neck surgery, (5) relieving obstructive sleep apnea, and (6) eliminating pulmonary “dead space.” Ideally, tracheotomies should be performed in a controlled setting—preferably in the operating room—where adequate lighting, instruments, specialized intubation equipment, and assistance are available.
Figure 38–4 depicts the surface anatomy of the neck and the location of the incision for the tracheotomy. The cricothyroid membrane has a relatively superficial location and is therefore fairly easy to access in an emergency situation. A tracheotomy is most easily performed if the patient is already intubated and general anesthesia has been administered. However, if the patient has a tenuous airway with impaired ventilatory status, the tracheotomy should be performed with local anesthesia and sedation to avoid paralysis. If the patient is anesthetized, he or she is placed in the supine position with a shoulder roll to extend the neck. The patient with a tenuous airway who undergoes a tracheotomy while awake should be placed in a semi-upright position. Landmarks such as the thyroid notch, the cricoid, the sternal notch, and planned incisions are marked. A transverse incision is marked approximately two fingerbreadths above the sternal notch. Alternately, a vertical incision can be used. The incision is then infiltrated with a local anesthetic containing epinephrine to help decrease bleeding. The neck and upper chest are then prepped and draped in a standard sterile fashion.
Diagram of the neck, indicating locations of cricothyroidotomy, and tracheotomy incisions.
The skin incision is made with a 15 blade and the platysma is divided. The strap muscles are then separated in the midline at the median raphe. The strap muscles can then be retracted laterally with appropriate retractors. The anterior jugular veins can also be retracted laterally or ligated and divided as needed. Once the strap muscles are retracted laterally, the thyroid isthmus should be visible in the center of the field. The surgeon can then retract the isthmus superiorly or inferiorly as needed to obtain exposure to the planned tracheotomy. Frequently, in order to facilitate exposure, the clinician can divide and ligate the isthmus. A cricoid hood is used to retract the cricoid superiorly and pull the trachea forward. A Kittner sponge dissector is then used to push the fine fascia away from the anterior wall of the trachea and clearly identify the individual rings. An incision is made between the second and third tracheal rings. A Björk flap can be made by creating an inferiorly based tracheal ring flap and suturing this flap to the inferior skin margin (Figure 38–5). This technique greatly reduces the incidence of accidental decannulation and makes reinsertion of the tracheotomy tube easier if inadvertent decannulation occurs. Alternately, the surgeon can also resect a single tracheal ring or make a cruciate incision (Figure 38–6). The Björk flap is contraindicated in children because it carries a high risk of tracheal stenosis and persistent tracheocutaneous fistula. It may also be less desirable in patients requiring tracheotomy for only a few days (eg, after maxillofacial trauma or extensive surgery of the oral cavity). Before making the intended tracheotomy incision, the physician should palpate the wound inferiorly to ensure that a high-riding innominate artery is not present; a higher tracheotomy incision may need to be made. After the trachea is entered, the endotracheal tube is withdrawn just proximal to the tracheotomy. A previously tested and appropriately sized cuffed tracheotomy tube is then inserted into the tracheotomy. The ventilator circuit is then switched to the tracheotomy tube, and satisfactory ventilation and oxygenation are confirmed by the anesthesiologist before the tracheal hook and retractors are removed. The tracheotomy plate is then secured to the neck with tracheotomy ties, sutures to the skin, or both. The endotracheal tube can then be removed.
Björk flap. The incised tracheal ring (see arrow) is then sutured to the inferior neck skin.
Various incisions used in entering the trachea. (A) Simple horizontal intercartilaginous incision; (B) resection of a cartilage ring creating an anterior tracheal window; (C) cruciate incision.
The emergent tracheotomy is best performed through a vertical incision, beginning at the level of the cricoid cartilage and extending approximately 1.0–1.5 in. If the surgeon is right-handed, the left hand stabilizes the larynx and the right hand holds the scalpel. The incision is made through skin, platysma, and subcutaneous tissues in one swift motion. Strap muscles and the thyroid isthmus are rarely identified during the maneuver. The left index finger is used to palpate the trachea. The blade is then used to incise the trachea where the second or third tracheal ring is estimated to be. Once the airway is entered, the endotracheal tube is inserted into the trachea. A tracheal dilator is useful, but not necessary. A tracheal hook is often helpful to pull the trachea forward and stabilize it while the endotracheal tube is passed. This technique is particularly helpful in the patient with an obese neck. During the procedure, significant bleeding is ignored until the airway is established; once it is, bleeding in the wound is controlled. If the situation allows, the tracheotomy should be carefully assessed and appropriate revisions made. The vertical skin incision is crucial to the speed of this procedure and can prevent damage to adjacent neck structures.
Tracheotomy in the child is carried out in a fashion similar to that of the adult tracheotomy; however, a simple vertical incision in the trachea is used. A Björk flap or the excision of tracheal rings should be avoided in the pediatric patient. Furthermore, tracheotomy in children should be performed with a bronchoscope or endotracheal tube in place to secure the airway. Emergent tracheotomy should be avoided, if possible. At the time of tracheotomy, it is wise to place 4.0 or 5.0 nonabsorbable monofilament guide sutures (one on either side of the vertical tracheal incision) to serve as guides should the tracheotomy tube accidentally come out. By gently pulling the sutures, the trachea can be elevated into the wound and the tracheal incision opened slightly to assist in tube reinsertion.
Since the release of commercially available kits in 1985, the popularity of percutaneous tracheotomy has increased, particularly in the critically ill patient population. While there are several different kits and techniques, the common characteristics include transcutaneous entry with a needle into the trachea, guide wire passage into the lumen, and serial dilation. A tracheotomy tube is then passed into the lumen. After more than two decades, debate continues regarding its safety and efficacy and whether it should represent the standard of care. Proponents argue that percutaneous tracheotomy is easy to perform, has a shorter operative time, ability to perform at bedside, lower expense, lack of need to transport the patient to the operating room with the inherent dangers associated with the transport (ie, unstable patient, line dislodgement), and may even have lower risks of complications. Opponents against percutaneous tracheotomy argue that potential greater complications associated with blind entry into the trachea. The time honored basic principle of exposure is sacrificed in this technique. Patients with obese necks also pose difficult candidates. The risk of blind entry and subsequent catastrophic results has been significantly decreased if one supplants the procedure with flexible bronchoscopic guidance to confirm entry into the trachea. The individual surgeon must weigh the costs and benefits of either procedure and make his or her own decision. Proper patient selection and endoscopic guidance should make the percutaneous technique as safe as open tracheotomies in experienced hands. With today's trend toward less invasive procedures as well as cost control pressures, the ability to offer this service can only enhance a surgeon's productivity. Regardless of which procedure is used, the physician must be skilled in open tracheotomies so that a percutaneous tracheotomy can be converted into an open procedure if the need arise.
Careful postoperative care is important to the success of tracheotomies. Humidifying inspired air is necessary to prevent crusting and tracheitis. Suctioning the tube and trachea on a frequent basis immediately postoperatively is necessary to clear secretions and prevent plugging. The frequency of suctioning can be decreased as the postoperative time increases and the patient recovers. Stay sutures and Björk flap sutures can be removed in approximately 3–5 days. Also, changing the tracheotomy tube can usually be performed at this time, after an adequate tract has formed.
Before decannulation can occur, the disease process that resulted in the need for a tracheotomy must be resolved. Good airway patency allows for successful decannulation. Patency can be evaluated either with a mirror exam of the larynx or by direct fiberoptic endoscopy. Another practical approach is to change the tube to a smaller uncuffed tube. This tube can then be occluded and the patient's respiration observed. The patient with an adequate airway after tube occlusion should tolerate decannulation; tube removal is usually performed after 24 hours of tube occlusion.