Synopsis of Ear, Nose, and Throat Anatomy

Figs. 70.1 to 70.4 illustrate various aspects of ENT anatomy. The oropharynx extends from the uvula to the hyoid bone. The hypopharynx extends from the hyoid to the cricoid cartilage. The glottis includes both vocal cords, the anterior commissure, and the posterior intraarytenoid area. The subglottis extends 5 mm (anteriorly) to 10 mm (posteriorly) below the apex of the vocal cords (also known as vocal folds). The larynx, essential to respiration and speech, has a clinically important glottic closure reflex mediated through bilateral superior laryngeal nerves. This reflex serves to protect the airway against aspiration. For example, swallowing activates this protective reflex. On occasion this protective reflex can be problematic because when sustained spasm of the glottic muscles (a condition known as laryngospasm) occurs, gas exchange cannot take place. Laryngospasm is associated with light anesthesia and is frequently triggered by blood or secretions irritating the vocal cords, as often occurs after septoplasty and rhinoplasty surgery. Because it can make ventilation impossible, laryngospasm may constitute a true anesthetic emergency (see later).

Highlights of otolaryngologic anatomy.

Note (1) the anterior position of the trachea relative to the esophagus; (2) the oropharynx, extending from the uvula to the hyoid bone; (3) the hypopharynx extending from the hyoid bone to the cricoid cartilage; (4) the cricoid ring, a structure that is pushed posteriorly during the Sellick maneuver component of rapid-sequence induction, done with the intention of occluding the esophagus to help prevent regurgitation of gastric contents; and (5) the location of the first tracheal ring, important as a surgical landmark because most tracheostomies are performed between the second and third tracheal rings.

From Feldman MA, Patel A. Anesthesia for eye, ear, nose, and throat surgery. In: Miller RD, ed. Miller’s Anesthesia . 7th ed. Philadelphia: Churchill Livingstone; 2010:2357–2388.

Anterior, posterior, midsagittal, and sagittal views of laryngeal anatomy.

Note (1) how the cartilaginous tracheal rings are incomplete posteriorly to allow the trachea to collapse slightly to facilitate the passage of food down the esophagus (and to provide orientation during bronchoscopic procedures!); (2) the superior cornu of the thyroid cartilage, an important landmark in the superior laryngeal nerve block because this is close to where the internal branch of the superior laryngeal nerve penetrates the thyrohyoid membrane; and (3) the median cricothyroid ligament and (not labeled) the twin lateral cricothyroid ligaments, known collectively as the cricothyroid ligament and entered in both emergency cricothyrotomy procedures and with emergency transtracheal jet ventilation.

From Feldman MA, Patel A. Anesthesia for eye, ear, nose, and throat surgery. In: Miller RD, ed. Miller’s Anesthesia . 7th ed. Philadelphia: Churchill Livingstone; 2010:2357–2388.

Laryngeal anatomy focusing primarily on the internal laryngeal nerve and the recurrent laryngeal nerve. The two recurrent laryngeal nerves provide motor innervation to all the intrinsic muscles of the larynx, except the cricothyroid and inferior pharyngeal constrictor muscles, which are innervated by the external branches of the two superior laryngeal nerves (external laryngeal nerve). Sensory innervation of the larynx down to the vocal cords is supplied by the internal laryngeal nerve branches of the superior laryngeal nerves (internal laryngeal nerve), these in turn being branches of the vagus. Sensory innervation below the vocal cords and to the upper trachea is supplied by the recurrent laryngeal nerves.

From Schuller DE, Schleuning AJ. Otolaryngology: Head and Neck Surgery. 8th ed. St. Louis: Mosby; 1994:252.

Lateral radiograph demonstrating laryngeal anatomy.

Notice (1) the normally wafer-thin epiglottis, which serves as a protective cover to the laryngeal inlet during swallowing and may become much larger and “thumb shaped” when edematous (e.g., as a result of pediatric epiglottitis); (2) the limited amount of prevertebral soft tissue in the oropharyngeal and hypopharyngeal regions; when edematous (e.g., as a result of a retropharyngeal abscess), this tissue may expand anteriorly to obstruct the airway; and (3) the hyoid bone, which aids in tongue movement and swallowing and which, if found fractured on autopsy, is suggestive of foul play by throttling or strangulation

From Feldman MA, Patel A. Anesthesia for eye, ear, nose, and throat surgery. In Miller RD, ed. Miller’s Anesthesia . 7th ed. Philadelphia: Churchill Livingstone; 2010:2357–2388.

Branches of the right and left vagus nerves innervate the larynx. The right vagus nerve gives rise to the right recurrent laryngeal nerve, whereas the left vagus nerve gives rise to the left recurrent laryngeal nerve. The two recurrent laryngeal nerves provide motor innervation to all the intrinsic muscles of the larynx, except the cricothyroid and inferior pharyngeal constrictor muscles, which are innervated by the branches of the superior laryngeal nerves. The internal laryngeal nerve is the internal branch of the superior laryngeal nerve (see Fig. 70.3 ). It descends to the thyrohyoid membrane, pierces it along with the superior laryngeal artery, and provides sensory innervation to the larynx down to the vocal cords. Sensory innervation below the vocal cords and to the upper trachea is supplied by the recurrent laryngeal nerves (see Fig. 70.3 ).

Injury to the recurrent laryngeal nerves, which supply most of the laryngeal intrinsic muscles, is a feared but often preventable complication in thyroid surgery and a host of other procedures, including tracheal intubation. If the damage is unilateral, the patient may present with hoarseness from unilateral loss of vocal cord abduction occurring in conjunction with intact cricothyroid-mediated adduction. This situation causes the affected vocal cord to assume a paramedian position. Bilateral nerve damage can result in dyspnea, stridor, and even full airway obstruction from bilateral vocal cord paramedian positioning. Such patients may require a tracheostomy. Intraoperative neuromonitoring is often used to reduce the chance of injury to the recurrent laryngeal nerves, especially in thyroid surgery.

Preoperative Evaluation for Ear, Nose, and Throat Surgery

Although the preoperative evaluation of the surgical patient is discussed in detail in Chapter 31 , a few issues are especially pertinent to ENT cases. Many ENT patients, especially those with malignant head and neck diseases, have histories of prolonged tobacco and alcohol use, whereas many others suffer from obesity or obstructive sleep apnea (OSA). Patients with chronic airway obstruction may develop pulmonary hypertension, sometimes leading to right-sided heart failure (cor pulmonale). A history of hoarseness may signal recurrent laryngeal nerve injury or worse, whereas the presence of stridor is always a cause for immediate concern. In cases involving the airway, the anesthesiologist and surgeon frequently review available radiographic and video studies to establish an airway plan collaboratively. A history of head and neck radiation for malignancy treatment frequently makes intubation difficult because the structures may become tough and fibrotic (“like wood”), yet they are predisposed to bleeding with instrumentation. A history of snoring may signal that the patient has undiagnosed sleep apnea and is prone to airway obstruction.

ENT cases frequently involve geriatric patients, many of whom are at a high risk for postoperative delirium and cognitive dysfunction. Although many ENT procedures involve infrequent risk, some of the large head and neck operation sare considered to have “intermediate” surgical risk. A preoperative resting 12-lead electrocardiogram (ECG) is recommended for patients with known coronary heart disease, peripheral arterial disease, or cerebrovascular disease who are undergoing such procedures. Additionally, patients with a history of heart failure, diabetes mellitus, or renal failure who are undergoing intermediate-risk operative procedures benefit from an ECG. Preoperative ECG testing is not indicated in asymptomatic persons undergoing infrequent-risk procedures.

A preoperative endoscopic airway examination can be performed in selected patients. This technique uses an ordinary flexible fiberscope usually used for awake endotracheal intubation to conduct a quick transnasal laryngoscopic examination using topical anesthesia. This examination allows the clinician to determine whether a problematic laryngeal disorder exists, such as supraglottic lesions that would not be apparent by ordinary means. The procedure requires minimal time and patient preparation, and it is well tolerated by patients. A review by Rosenblatt provides ample details.

Airway Management in Otolaryngology

Both easy and difficult airways are frequently encountered in ENT anesthesia. The American Society of Anesthesiologists (ASA) Difficult Airway Algorithm (or similar algorithm), should ordinarily be a starting point for nearly all aspects of ENT airway management. To a large extent, the specific airway management techniques chosen depend on clinical circumstances, the airway management skills and preferences of the anesthesiologist and surgeon, and the available equipment.

The following general management options exist: (1) general endotracheal anesthesia; (2) general anesthesia using a supraglottic airway (SGA) device (e.g., laryngeal mask airway [LMA]); (3) general anesthesia using an ENT laryngoscope (to expose the airway) in conjunction with jet ventilation; (4) use of intermittent apnea; (5) general anesthesia using the patient’s natural airway, with or without adjuncts such as jaw positioning devices or nasopharyngeal airways; and (6) local anesthesia in conjunction with intravenous sedation, with the patient breathing spontaneously. The first option is doubtless the most popular. However, the technique chosen and implemented depends on factors such as the perceived difficulty of intubating the trachea with ordinary methods. Evaluation of the airway in this particular respect is also discussed in Chapter 44 .

The airway can become obstructed for many reasons. Examples include the following: aspirated foreign bodies; infections such as epiglottitis, diphtheria, or Ludwig angina; laryngospasm; tumors and hematomas impinging on the airway; trauma to the airway; OSA; tonsillar hypertrophy; and airway edema (e.g., from anaphylaxis, prolonged laryngoscopy, or smoke inhalation or burn injury). In most cases, airway management is determined after a discussion between the anesthesia and surgical teams.

Most patients undergoing ENT surgery have their airway managed by tracheal intubation. Although under ordinary circumstances tracheal intubation is straightforward, patients whose tracheas are expected to be difficult to intubate can be identified and usually managed with techniques such as videolaryngoscopy or fiberoptic intubation. A key decision in such cases is whether the tracheal intubation should be performed with the patient awake or following the induction of general anesthesia. Another important decision is what tools or interventions to employ in the event that difficulty with ventilation or intubation is encountered. In exceptional cases, a tracheostomy using local anesthesia must be performed.

Patients for ENT surgery are often managed using an ordinary polyvinyl chloride (PVC) endotracheal tube (ETT), but microlaryngeal tubes (MLTs), laser tubes, and wire-reinforced tubes are also frequently used. Reinforced tubes have the advantages that they are unlikely to kink and they fit especially well into tracheostomy stomas because of their excellent flexibility. Selection of laser-resistant ETTs should be made based on the material appropriate to the type of laser being used for the procedure. In addition, the tracheal cuff can be filled with saline dyed with methylene blue to allow immediate detection of laser injury to the cuff. Practical considerations in this setting start with the fact that the tube must be adequately secured using tape or other means; some maxillofacial surgeons suture the tube to the side of the mouth or even tie the tube to the teeth with wire. In addition, the ETT cuff pressures ordinarily must be kept less than 25 mm Hg to avoid ischemic damage to the tracheal mucosa. When nitrous oxide is used, cuff pressures gradually increase as nitrous oxide enters the cuff by diffusion. This is of particular concern in surgical procedures of long duration, such as free-flap surgery.

Before attempting tracheal intubation, its difficulty using direct laryngoscopy can often be predicted. The 11-point airway assessment tool included with the 2003 ASA Difficult Airway Algorithm is an excellent source of information and advice. In addition, following the completion of tracheal intubation, the difficulty (if any) encountered should be summarized. The Intubation Difficulty Scale (IDS) introduced by Adnet and associates can be useful. IDS is a numeric score indicating overall intubation difficulty based on seven descriptors associated with intubation difficulty: number of supplementary intubation attempts, number of supplementary operators, alternative techniques used, laryngoscopic grade, subjective lifting force, the use of external laryngeal manipulation, and the characteristics of the vocal cords.

Most endotracheal intubations are achieved using traditional Macintosh and Miller laryngoscopes, although several alternative laryngoscopes have been advocated. When the view at laryngoscopy is suboptimal, the use of introducers such as the Eschmann stylet (gum elastic bougie) can sometimes be very helpful. It is used as follows: when a poor laryngoscopic view of the glottic structures is obtained, the introducer should be inserted into the patient’s mouth and gently advanced through the glottic opening (in the case of a grade II view) or anteriorly under the epiglottis (in the case of a grade III view). Subtle clicks resulting from the introducer passing over the tracheal rings help confirm proper placement of the introducer. With the introducer held steady, one then “railroads” a tracheal tube over the introducer into the glottis.

Video laryngoscopes such as the GlideScope (Verathon, Bothell, WA), the McGrath (Covidien, Mansfield, MA) video laryngoscope, the Storz video laryngoscope (Karl Storz, Tuttlingen, Germany), and the Pentax AWS (Hoya Corporation, Tokyo) have become particularly valuable, especially in patients with an “anterior” larynx or in patients with cervical spine immobilization.

As discussed in Chapter 44 , awake endotracheal intubation involves ETT insertion in a conscious or lightly sedated patient. It is usually performed because endotracheal intubation during general anesthesia is judged to be too risky. Some concerns may reflect possible difficulties with ventilation or endotracheal intubation or possible aspiration of gastric contents. Although fiberoptic intubation using topical anesthesia is the most common approach to awake endotracheal intubation, other methods include awake blind nasal intubation using an Endotrol (or similar) ETT or the use of a Macintosh, Miller, GlideScope, or other laryngoscope with topical anesthesia. Certain airway blocks can be used in addition to topical anesthesia. These are discussed in Chapter 44 .

The use of fiberoptic intubation for the airway management of patients undergoing otolaryngologic surgery is popular because this technique works well in the presence of many kinds of airway disease. Although fiberoptic intubation can often be safely performed during complete general anesthesia, many clinicians opt to perform this technique using topical anesthesia with the patient only lightly sedated (awake fiberoptic intubation), depending on the skill level of the anesthesiologist, the cooperation of the patient, and the severity of the pathologic process. A central consideration behind the choice of “awake” versus “asleep” fiberoptic intubation is the safety margin an awake technique allows: if intubation is not successfully accomplished, the patient’s ability to maintain his or her own airway remains intact. In addition, during awake intubation, airway reflexes are generally maintained sufficiently to guard against pulmonary aspiration, an important point in patients with a high risk of aspiration of gastric contents. Patients who have recently eaten and have undergone trauma are at especially high risk.

Awake endotracheal intubation is not synonymous with fiberoptic intubation. Awake intubation can be ac-complished safely using many other airway devices. Other possible options for awake intubation include, but are not limited to, direct laryngoscopy with Macintosh and Miller laryngoscopes, blind nasal intubation, use of a GlideScope or other video laryngoscope, use of a lighted stylet, and so on.

Typically, in intubation of the trachea in an awake patient, the airway is initially anesthetized with gargled and atomized 4% lidocaine. Superior laryngeal and transtracheal blocks are occasionally also employed. In addition, judicious sedation is usually administered. Midazolam, fentanyl, remifentanil, ketamine, propofol, and clonidine have all been used in this setting. More recently, the use of dexmedetomidine, a selective α ₂ -agonist with sedative, analgesic, amnestic, and antisialagogue properties, has been reported. A key advantage of dexmedetomidine is that it maintains spontaneous respiration with minimal respiratory depression. Patients being sedated with dexmedetomidine are generally easy to arouse. However, this advantage, along with that of maintaining spontaneous respiration, may not occur when very large doses are given.

Doyle described the successful use of the GlideScope in four cases of awake endotracheal intubation. The potential advantages are as follows: first, the view is generally excellent. Second, the method is less affected by the presence of secretions or blood as compared with the use of fiberoptic intubation. Third, no special restrictions exist on the type of ETT that can be placed when using the GlideScope, but this is not the case for fiberoptic methods. Fourth, the GlideScope is much more rugged than a fiberoptic bronchoscope and is far less likely to be damaged with use. Advancing the ETT into the trachea over the fiberoptic bronchoscope often fails as a result of ETT impingement on the arytenoid cartilages; this is generally not a problem with the GlideScope.

In the end, however, the use of awake fiberoptic intubation in the setting of the patient with airway disease remains steadfastly popular because it is gentle to the airway, is generally well tolerated, and does not require the application of force to obtain glottic exposure.

Special mention needs to be made of the necessity of being fully prepared for dire ENT airway emergencies because these patients may require immediate surgical intervention. In addition to a conventional difficult airway cart, practitioners may wish to maintain a special ENT airway cart with equipment such as that listed in Box 70.1 . In addition to these items and unlisted items favored by individual practitioners, ENT surgeons want ready access to an emergency tracheotomy tray, as well as to some form of suspension laryngoscope or rigid bronchoscope. Special attention to the maintenance and cleaning of fiberoptic bronchoscopes is also important, given that they must always be easily accessible and reliable when needed. In the case of electronic fiberscopes incorporating a video display, it is particularly important to establish that illumination settings and white balancing have been correctly set before use.

Airway Disorders in Otolaryngology

Otolaryngologic airway disorders can sometimes present the clinician with tremendous anesthetic and airway challenges. In many such cases, awake endotracheal intubation (e.g., by fiberoptic methods) is the method of choice. When awake intubation is impractical (e.g., overwhelming tumor invasion of the airway, inadequate equipment, limited experience), tracheostomy using local anesthesia (with minimal sedation, or no sedation in extreme cases) is sometimes preferred. In such cases, complete airway obstruction is the outcome most feared; this can occur when anesthetic drugs or neuromuscular blocking drugs decrease the tone of the airway musculature, thereby unfavorably changing the airway architecture.

Many ENT pathologic conditions can make airway management difficult. Airway infections can include upper airway abscesses, retropharyngeal abscesses, quinsy, Ludwig angina, and epiglottitis (supraglottitis). Airway tumors may be present as oral or tongue malignancies, as glottic, supraglottic, and infraglottic tumors, or as anterior mediastinal masses. Other pathologic conditions may also complicate airway management, such as congenital malformations (Pierre-Robin sequence, Goldenhar syndrome), periglottic edema (e.g., following rigid bronchoscopy), recurrent laryngeal nerve injury (e.g., following thyroid surgery), maxillofacial trauma, or OSA. Some of the more important of these conditions are discussed in the following paragraphs.

Airway Tumors, Polyps, and Granulomas

Airway tumors can be benign or malignant ( Figs. 70.5-70.7 ), but regardless of their pathologic characteristics, airway obstruction is always a potential concern. Discussion with the surgical team concerning the size and location of the tumor, along with a review of any video-recorded nasopharyngeal video examinations, will help determine whether awake endotracheal intubation is needed. Polyps may also be found throughout the airway and can lead to partial or complete airway obstruction. Vocal cord polyps, cysts, and granulomas may result from traumatic intubation, vocal cord irritation from ETT movement, or other causes, especially in women. Vocal cord cancer can also occur. The potential also exists for exacerbation of asthma in patients with nasal polyps who receive aspirin, ketorolac (Toradol), and other nonsteroidal antiinflammatory drugs (NSAIDs) (the Samter triad).

Vocal cord lesions with little or no airway compromise.

(A) Normal vocal cord. (B) Minor right vocal cord lesion. (C) Granuloma on the middle right vocal cord. (D) Kissing nodule on the right vocal cord. (E) Anterior webbing of the vocal cord. (F) Intubation granuloma.

From Feldman MA, Patel A. Anesthesia for eye, ear, nose, and throat surgery. In: Miller RD, ed. Miller’s Anesthesia . 7th ed. Philadelphia: Churchill Livingstone; 2010:2357–2388.

Vocal cord lesions with significant airway compromise.

(A) Papilloma of both vocal cords. (B) Bilateral Reinke edema. (C) Left vocal cord polyp. (D) Anterior glottic granuloma. (E) Epiglottic edema. (F) Vocal cord cyst.

From Feldman MA, Patel A. Anesthesia for eye, ear, nose, and throat surgery. In: Miller RD, ed. Miller’s Anesthesia. 7th ed. Philadelphia: Churchill Livingstone; 2010:2357–2388.

Vocal cord lesions with severe airway compromise.

(A) Papilloma of vocal cord. (B) Severe subglottic stenosis (2-mm airway). (C) Bilateral papilloma. (D) Extensive supraglottic carcinoma.(E) Acute epiglottitis. (F) Laryngeal carcinoma.

From Feldman MA, Patel A. Anesthesia for eye, ear, nose, and throat surgery. In: Miller RD, ed. Miller’s Anesthesia. 7th ed. Philadelphia: Churchill Livingstone; 2010:2357–2388.

Anesthesia for Panendoscopy

Panendoscopy, sometimes known as triple endoscopy, involves three diagnostic components: laryngoscopy, bronchoscopy, and esophagoscopy. Such procedures and others involving the larynx, pharynx, or trachea often require specialized ENT laryngoscopes, frequently in conjunction with a small-diameter ETT or a tube specifically designed for laser surgery. Panendoscopy is used in patients with head and neck cancer to search for vocal cord lesions, obtain tissue biopsies, monitor for tumor recurrence, and so on. In such cases, one should consider the following specific issues in discussion with the surgical team: what is the anticipated pathologic process, and how is it expected to affect intubation or ventilation? (In some cases the patient’s disease may not allow the use of an ETT, so that jet ventilation or a rigid bronchoscope is needed.) What is the plan for airway management, and how does it affect the delivery of anesthesia? How does the presence of coexisting disease (e.g., coronary artery disease, chronic obstructive pulmonary disease, gastroesophageal reflux disease) affect management? What specialized equipment may be needed? (For example, when airway obstruction is present, the surgeon may employ dilatational balloons, lasers, or a microdébrider to open up the airway.)

Five airway options for panendoscopy exist: (1) use of an ETT, typically a narrow-bore MLT that provides the surgeon with a superior glottic view; (2) jet ventilation in conjunction with a rigid ENT laryngoscope, without the use of an ETT; (3) hybrid methods, such as the intermittent use of an SGA or an MLT tube in conjunction with a rigid laryngoscope, jet ventilation, or intermittent apnea; (4) tracheostomy using local anesthesia before inducing general anesthesia; and (5) elective placement of a specially designed transtracheal jet ventilation cannula (e.g., Ravussin jet ventilation catheter before induction ). The last two options are only occasionally used for patients with a suspected difficult airway; awake tracheal intubation is the most common approach in patients with a difficult airway. Moreover, when jet ventilation is used, total intravenous anesthesia (TIVA), for example with infusions of propofol and remifentanil, is needed. Finally, when panendoscopy is combined with laser surgery, a laser-safe ETT is often used.

Panendoscopy is generally done while the patient is under general anesthesia with the patient’s neck flexed and the head extended, usually employing a shoulder roll and a head ring (Jackson position). Typically, an anterior commissure laryngoscope is used and fixed into position by suspension ( Fig. 70.8 ). This technique allows the surgeon’s hands to be free and the operating microscope to be used. Other specialized ENT surgical laryngoscopes that are commonly used, often in conjunction with a microscope for laryngeal microsurgery, include the Dedo laryngoscope (Elmed, Addison, IL) and the Universal Modular Glottiscope (Endocraft, Providence, RI). Here, once the laryngoscope is correctly configured (“suspended”), the surgeon brings the operating microscope into the field and uses a variety of microlaryngeal instruments to treat the patient.

Patient undergoing an ear, nose, and throat procedure using a suspended anterior commissure laryngoscope. A jet ventilation attachment is taped to the handle. A fiberoptic bronchoscope with a laser fiber is in use to deliver laser pulses to areas of pathologic tissue.

Image courtesy Dr. Basem Abdelmalak, Cleveland Clinic.

A variety of anesthetic techniques can be used for panendoscopy procedures. The most common approach is to perform the procedure while the patient is under general anesthesia with muscle relaxation in conjunction with an MLT-type tracheal tube ( Fig. 70.9 ). This technique is familiar to anesthesiologists, provides both airway protection and control of ventilation, allows for reliable capnographic carbon dioxide (CO ₂ ) measurements, and allows for the use of volatile anesthetics without operating room pollution. Disadvantages of the technique include higher than usual ventilation pressures as a consequence of the tube’s narrow diameter, somewhat hindered surgical access, and concerns for tube ignition when a laser is in use.

Regular 7.5-mm inner diameter (ID) tracheal tube (top) in comparison with a 5.0-mm ID microlaryngeal (MLT) –type tracheal tube (bottom). The MLT tube has a narrow lumen that provides the surgeon with improved glottic exposure at the cost of higher ventilation pressures.

Because a tracheal tube may impair access to some glottic structures, however, some cases are performed using intermittent apnea during general anesthesia and administration of neuromuscular blocking drugs. Disadvantages of this technique include the need for a TIVA technique, the need for repeated intubation-extubation cycles (potentially producing glottic trauma), fragmentation of the surgical work into brief apneic segments, and the repeated interruption of ventilation and oxygenation.

Next, panendoscopy is often performed using supraglottic jet ventilation. This technique requires TIVA and entails some special issues because it involves the delivery of high-pressure oxygen pulses (typically 20-50 psi in adults, frequently delivered 1 second on/3 seconds off), usually through an adapter that attaches to the surgical laryngoscope. Additionally, subglottic methods (e.g., using a Hunsaker catheter ) and transtracheal methods of jet ventilation have been described. Each pulse of oxygen entrains room air, thus increasing the gas volume delivered and diluting the oxygen concentration (Venturi effect). Disadvantages of jet ventilation include the need for TIVA, the potential for barotrauma (remember that a pressure of 50 psi is equivalent to 3515 cm H ₂ O), an inability to measure either end-tidal CO ₂ (ETCO ₂ ) or tidal volume easily, and the fact that the technique is often suboptimal in obese individuals. Finally, a variant of jet ventilation known as high-frequency jet ventilation is sometimes used in these cases, often in conjunction with a special ventilator, an intratracheal catheter, and transcutaneous CO ₂ monitoring.

Otolaryngologic Trauma

Although the topic of anesthesia care for the trauma patient is the subject of Chapter 66 , a few special points pertaining to patients who have undergone head and neck trauma should be emphasized. First, patients with head and neck trauma may have a concurrent brain injury or injury to the cervical spine. Until cleared of a possible cervical spine injury, patients should be placed in a rigid cervical collar. In addition, although placing the patient’s head in the customary “sniffing” position can facilitate laryngoscopy, this technique is contraindicated in patients with a suspected cervical spine injury for fear of exacerbating any injury. Additionally, jaw thrust and chin lift maneuvers can be more difficult when a cervical collar is used or when comminuted mandibular fractures are present.

Second, facial injuries can produce extensive bleeding, as well as the aspiration of blood, bone, cartilage, teeth, and tissue fragments. Third, the airway may be compromised, especially when bilateral mandibular fractures are present. Airway trauma from blunt or penetrating injuries, burns, inhalational injury, or even iatrogenic causes may be present. Immediate airway management options include orotracheal intubation (awake versus rapid-sequence induction), a surgical airway carried out using local anesthesia, or even intubation through an open airway in cases of tracheal transection. Oropharyngeal airways may not be tolerated in patients with an intact gag reflex, and inserting a nasopharyngeal airway may exacerbate bleeding.

Although fiberoptic intubation would seem to offer many advantages in trauma cases, clinical experience suggests otherwise, at least in some cases, because navigating through a distorted airway filled with blood and foamy secretions challenges even the most experienced bronchoscopists. Special concerns exist when the trachea is intubated in a patient with laryngeal trauma because this may result in further injury or even complete airway loss (e.g., in the event of inadvertent ETT placement through a laryngeal fracture into the mediastinum). Clinical findings suggestive of laryngeal trauma include abrasions, discoloration, indentation, bleeding, or pain in the region of the larynx, as well as dyspnea, dysphagia, dysphonia, stridor, hemoptysis, subcutaneous emphysema, and hoarseness. Signs of pneumothorax may also be present, whereas fiberoptic endoscopic examination may reveal edema, the presence of bleeding or hematoma, or abnormal vocal cord function. If endotracheal intubation is attempted in this setting, a fiberoptic bronchoscope with a small-diameter ETT can be used carefully, bearing in mind the foregoing concerns about fiberoptic intubation in the trauma setting. Additionally, positive-pressure ventilation by mask or SGA in this setting may worsen any subcutaneous emphysema. A tracheostomy may be the most prudent course in some cases. Finally, the application of cricoid pressure in blunt laryngeal trauma may result in cricotracheal separation and so is contraindicated. In any event, in both facial trauma and airway trauma, initial management is dictated by the degree of respiratory distress or potential airway compromise, the available equipment, and clinical preferences.

Midfacial fractures deserve special mention. These fractures are defined by the Le Fort classification. A Le Fort I fracture is a horizontal fracture that involves the inferior nasal aperture, separating the maxillary alveolus from the rest of the midfacial skeleton. Le Fort II fractures are pyramidal nasomaxillary fractures that break from the upper craniofacial skeleton. Le Fort III fractures, less commonly encountered than the others, involve the separation of the facial skeleton from the skull base. These fractures are illustrated in Figure 70.10 .

Classification of midfacial fractures.

Le Fort I: alveolar fracture. Le Fort II: zygomatic-maxillary complex fracture. Le Fort III: cranial facial dysostosis with separation of the midface from the skull.

From Schuller DE, Schleuning AJ. Otolaryngology: Head and Neck Surgery. 8th ed. St. Louis: Mosby; 1994:157.

Nasal Surgery

Nasal surgery can involve external procedures, procedures within the nasal cavity, surgery involving the nasal bones, and nasal sinus surgery. Besides the usual concerns, preoperative assessment should focus on the suitability of topical nasal vasoconstrictor use, the possibility of undiagnosed OSA, and the potential presence of the Samter triad (nasal polyps, asthma, and a sensitivity to aspirin and NSAIDs that may produce deadly bronchospasm). Because postoperative bleeding is a common complication after nasal surgery, patients should not be taking NSAIDs and aspirin for 1 to 2 weeks preoperatively.

Preoperative planning begins by deciding whether the procedure is best performed with local (usually accompanied by intravenous sedation) or general anesthesia. Although local anesthesia may be suitable for simple procedures such as cauterization or straightforward polypectomy or turbinectomy surgery in adults, often general anesthesia is required. When general anesthesia is chosen, a choice must then be made among a simple facemask (as may be appropriate for pediatric myringotomy surgery), an SGA device (e.g., flexible LMA), and a tracheal tube (e.g., an unkinkable wire-reinforced design). This decision should be made jointly with the surgeon. Although the use of an SGA during ENT surgery has its enthusiasts, negative experiences, such as airway obstruction related to device malpositioning, have led many clinicians to prefer a tracheal tube in such cases.

Patients undergoing rhinoplasty are typically young, healthy individuals requiring reconstruction of the external nose for deformity treatment. Septoplasty (correction of a deviated septum) and surgery to remove nasal polyps are often performed to improve nasal airflow and ventilation of the sinuses. Some malignant lesions require excision of the entire nose with follow-up staged reconstruction using a forehead flap. Open nasal fracture reduction procedures are usually performed after the initial swelling has resolved; if the injury is corrected too late, the bones can be difficult to align and can lead to significant surgical bleeding. General endotracheal anesthesia is usually carried out in such cases, often using a midline reinforced ETT taped to the chin. In closed nasal fracture reduction, the surgeon applies forceful pressure to realign the nasal bones, a procedure that usually takes only a few seconds but nevertheless is so intensely painful that the procedure is usually preceded by a single induction dose of propofol, followed by airway support as needed as a nasal cast is applied. However, when the reduction is expected to be bloody or otherwise complicated, the airway is usually protected with an ETT or an SGA device. In many of these procedures, nasal packs, stents, and/or casts are placed; nasal stents offer an advantage over packs in that one can breathe through them.

In many ENT cases, a “throat pack” made of a long piece of saline-soaked gauze is stuffed around the ETT to prevent blood and surgical debris from entering the pharynx and larynx. Typically, a few inches of gauze are kept outside the mouth as a reminder of its presence, because an inadvertently retained pack can lead to catastrophic airway obstruction after extubation. In addition to suctioning, many clinicians follow throat pack removal with pre-extubation laryngoscopy and a neck flexion-extension maneuver to encourage any residual clot (the so-called “coroner’s clot”) to fall past the soft palate into a position where it can be removed under direct vision.

Gentle awakening in nasal surgery is important because coughing and bucking on emergence frequently produce undesirable bleeding. Techniques that are often helpful include the use of a remifentanil infusion and the application of lidocaine down the ETT with the cuff temporarily deflated while the patient is still under deep anesthesia. Oral and gastric suction before emergence will decrease the incidence of postoperative nausea and vomiting (PONV). When nasal packing is used, patients should be advised before induction of anesthesia that, on emergence, they should breathe through the mouth. On awakening, applying pressure on the nose with a facemask should not be done for fear of ruining the surgeon’s handiwork. In addition, all postoperative patients with nasal packs will have obstructed nasal passages unless nasopharyngeal airways are incorporated into the nasal pack, and patients with OSA are in particular need of careful postoperative respiratory monitoring. Finally, postoperative pain in these procedures usually does not require opiates, and the use of oral acetaminophen and an NSAID usually suffices.

In many of these procedures, a topical vasoconstrictor such as phenylephrine, oxymetazoline, or cocaine is used. Although these topical agents are important drugs that reduce bleeding and improve visualization during nasal and endoscopic procedures, they sometimes produce cardiovascular toxicity. The cardiovascular effects of cocaine, usually administered as a 4% (40 mg/mL) topical solution, result from the drug’s blocking the reuptake of norepinephrine at sympathetic nerve terminals. Consequently, cocaine would not be a first-choice vasoconstrictor in patients with coronary artery disease or hypertension, or in patients taking monoamine oxidase inhibitors. When cocaine use is appropriate, the dose should not ordinarily exceed 1.5 mg/kg.

Phenylephrine is an α-adrenergic agonist topical vasoconstrictor either used alone or in combination with lidocaine. The initial dose should not exceed 500 μg (<20 μg/kg in children ≤25 kg). Because severe hypertension sometimes results following phenylephrine use, blood pressure monitoring is particularly important. Instances of unacceptable hypertension should be treated with direct vasodilators or α-receptor antagonists; the use of β-adrenergic and calcium channel blockers should be avoided because they may worsen cardiac output and produce pulmonary edema.

Oxymetazoline, a selective α ₁ -agonist and partial α ₂ -agonist imidazoline-derivative, is perhaps the most popular topical vasoconstrictor in ENT surgery, primarily because of its excellent safety profile and availability as an over-the-counter product. Three sprays of 0.05% solution are administered in each nostril. This drug should be avoided in patients taking monoamine oxidase inhibitors. However, despite its relative safety, complications have been reported.

Tonsillectomy and Adenoidectomy

The adenoids are a mass of lymphoid tissue located posterior to the nasal cavity, in the roof of the nasopharynx. If this tissue becomes hyperplasic, nasopharyngeal obstruction and a number of related problems can occur such that the adenoids merit surgical removal (adenoidectomy). When removed, the tonsils are usually taken as well. Other indications for tonsillectomy include tonsillar hyperplasia, recurrent tonsillitis, and malignant disease. An especially important consideration here is that chronic oropharyngeal airway obstruction as a consequence of tonsillar hypertrophy can lead to OSA and its attendant complications (daytime sombulence, cor pulmonale, pulmonary hypertension, right ventricular hypertrophy, cardiomegaly). In addition to the usual, preoperative assessment focuses on findings suggestive of OSA, possible cardiac comorbidities, and a history of recurrent upper respiratory tract infections. The presence of a fever or a productive cough may be grounds for postponement of the surgery or for postoperative care in setting of increased vigilance (e.g., ICU or step-down facility), especially in infants.

Induction of anesthesia in adults usually entails administering intravenous drugs, whereas inhaled inductions are popular with children, followed by placement of an intravenous catheter and administration of glycopyrrolate. Oral RAE (named after the inventors Ring, Adair, and Elwyn) tracheal tubes or wire-reinforced tubes, taped in the midline to the mandible, are often preferred by surgeons and are less likely to kink following retractor placement. When a tonsillar or parapharyngeal abscess is present, the patient may have a compromised airway complicated by trismus and pharyngeal edema. Although awake abscess decompression by needle aspiration before the induction of anesthesia is sometimes done, awake fiberoptic intubation is the usual approach in this setting.

At the end of the surgical procedure, the throat pack, if previously placed, should be removed, the oropharynx should then be suctioned, and an orogastric tube should be used to empty the stomach. Extubation is sometimes performed using deep anesthesia but more commonly is carried out when the patient has intact airway reflexes. Coughing on the tracheal tube on emergence may be attenuated by the administration of lidocaine, either given intravenously or placed down the tracheal tube with the cuff temporarily deflated. Emergence on a light remifentanil infusion can also be beneficial.

Posttonsillectomy hemorrhage is a dreaded surgical emergency, especially in children. It usually occurs within the first six postoperative hours, but it can also occur several days later. When possible, the patient should receive appropriate intravenous fluids preoperatively (including blood products when necessary). The presence of hypovolemia may dictate a reduction in induction drug dosage or the use of etomidate. Because the stomach may contain a considerable amount of blood, a rapid-sequence induction with cricoid pressure is usually performed with a view to protect the airway from aspiration of gastric contents. Vigorous suctioning is also needed to remove the copious oropharyngeal blood likely to be found during laryngoscopy.

Endoscopic Sinus Surgery

Endoscopic sinus surgery has become a common ENT procedure. Indications are varied and include conditions such as nasal polyposis, recurrent or chronic sinusitis, epistaxis control, tumor excision, orbital decompression (e.g., for Graves ophthalmopathy), foreign body removal, treatment of sinus mucoceles, and more.

Proper anesthetic management helps ensure a good outcome. Considerations in such cases include local versus general anesthesia, SGA device versus ETT, and inhaled anesthesia versus TIVA, and preferences of the surgeon and anesthesiologist as well as patient comorbidities are taken into account. The most important goals are a blood-free surgical field, patient immobility, stable cardiorespiratory conditions, and gentle emergence from anesthesia. Controlled hypotension is sometimes used to improve surgical conditions; when this approach is used, intraoperative β-adrenergic blockade is associated with better operating conditions than when vasodilation drugs are administered.

Despite minimal arterial blood pressure differences, propofol-remifentanil intravenous anesthesia may provide better surgical conditions as compared with a traditional balanced technique (e.g., using an isoflurane-opiate technique), possibly because of lower heart rates and cardiac output. Use of an SGA device is preferred to an ETT because of better surgical conditions and smoother emergence. However, SGA devices are prone to malpositioning and provide less protection from gastric regurgitation as compared with an ETT.

The procedure typically begins with decongestion of the nose and infiltration of 1% lidocaine with 1:100,000 epinephrine, often followed by the bilateral nasal placement of pledgets soaked in 4% cocaine. In most cases, an image-guided surgical system is used; this allows the surgeon to know exactly where he or she is operating by using a preoperative CT scan. This technology allows the surgeon to visualize four different views simultaneously: the coronal, sagittal, and axial CT scan images at the same time as the real-time endoscopic view. This system requires a special headset that may preclude the use of electroencephalographic (bispectral index) monitoring.

Given the close proximity of major blood vessels and nerves, the orbit, and the brain, complications are possible, especially when the surgical landmarks are obscured by blood. Some major complications include orbital hematoma formation, blindness from orbital trauma or damage to the optic nerve, formation of cerebrospinal fluid leak, carotid or ethmoid artery invasion, entry into the cranial cavity, severe hemorrhage, and death.

Finally, not all sinus surgery is endoscopic. For example, although now largely replaced by endoscopic methods, the once common Caldwell-Luc procedure involves fenestration of the anterior wall of the maxillary sinus with surgical drainage of this sinus into the nose through an antrostomy.

Thyroid and Parathyroid Surgery

The usual indications for thyroid surgery include thyroid cancer, symptomatic thyroid goiter, and failed medical management of hyperthyroidism; the surgical procedure is almost always elective. The most common indication for parathyroid surgery is hypercalcemia from hyperparathyroidism secondary to a benign parathyroid adenoma. When the hypercalcemia is severe, preoperative treatment (e.g., fluids, furosemide, bisphosphonates) may be needed.

Hyperthyroid patients should be treated preoperatively to reduce the risk of thyroid storm (thyrotoxicosis). Thyrotoxic patients may experience sinus tachycardia, atrial fibrillation, myocardial ischemia, congestive heart failure, nervousness, tremulousness, insomnia, heat intolerance, weight loss, and other findings.

Large goiters may result in deviation of the larynx, tracheal compression leading to considerable airway narrowing, Horner syndrome, or superior vena cava obstruction, especially with retrosternal extension. Preoperative airway evaluation by endoscopic examination and by CT is often useful to determine the extent of the disease and the possibility that sternotomy will be needed.

General anesthesia with tracheal intubation and muscle relaxation is usually employed, although many surgeons routinely use a nerve integrity monitor (NIM) ETT for neuromonitoring, in which case neuromuscular blocking drugs must be avoided in the postintubation period. Gentle emergence from anesthesia is necessary to avoid coughing on the ETT and the possibility of hematoma formation from venous engorgement. The use of a small-dose remifentanil infusion (0.01-0.05 μg/kg/min) in the extubation period is a popular means to diminish coughing on the ETT. Although deep extubation also reduces the incidence of bucking and straining, many clinicians avoid this technique wherever possible because of airway obstruction.

Possible complications of thyroid and parathyroid surgery include hematoma formation (possibly resulting in airway impairment), vocal cord dysfunction from recurrent laryngeal nerve injury, pneumothorax, and other conditions. In patients with compressive goiters, postthyroidectomy tracheomalacia may occur following goiter excision. In postoperative patients who have undergone parathyroid and total thyroidectomy, serial calcium levels are taken to detect inadvertent hypocalcemia.

Airway Fires

An airway fire is a potentially deadly complication that may occur during tracheotomy surgery, during laser surgery to the airway, and elsewhere. For a fire to occur, the triad of fuel (e.g., ETT, drapes, sponges), oxygen, and an ignition source (e.g., laser or electrocautery) is needed. The ASA published an Operating Room Fires Algorithm ( Fig. 70.11 ), to which the reader is referred. An additional helpful resource is a checklist developed by Dr. B. Abdelmalak ( Box 70.2 ). Prevailing conventional wisdom, at least until recently, holds that cases of airway fire call for immediate removal of the ETT. Although this is a reasonable rule of thumb, it should also be noted that in some patients removal of the ETT would result in irreversible loss of the airway. Clinicians in such a setting face a particularly difficult choice: leave the ETT in place and risk fire-related injury to the patient, or remove the ETT and risk deadly loss of the airway.

American Society of Anesthesiologists’ Operating Room Fires (1) Ignition sources include but are not limited to electrosurgery or electrocautery units and lasers. (2) An oxidizer-enriched atmosphere occurs when there is any increase in oxygen concentration above room air level, and/or the presence of any concentration of nitrous oxide. (3) After minimizing delivered oxygen, wait a period of time (e.g., 1-3 min) before using an ignition source. For oxygen dependent patients, reduce supplemental oxygen delivery to the minimum required to avoid hypoxia. Monitor oxygenation with pulse oximetry, and if feasible, inspired, exhaled, and/or delivered oxygen concentration. (4) After stopping the delivery of nitrous oxide, wait a period of time (e.g., 1-3 min) before using an ignition source. (5) Unexpected flash, flame, smoke or heat, unusual sounds (e.g., a “pop,” snap or “foomp”) or odors, unexpected movement of drapes, discoloration of drapes or breathing circuit, unexpected patient movement or complaint. (6) In this algorithm, airway fire refers to a fire in the airway or breathing circuit. (7) A CO2 fire extinguisher may be used on the patient if necessary.

Algorithm. CO ₂ , carbon dioxide; OR, operating room.

From American Society of Anesthesiologists. Practice advisory for the prevention and management of operating room fires. Anesthesiology. 2008;108:786–801. Copyright 2013, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins. Anesthesiology 2013; 118:00-00

Ear Surgery

Ear operations range from simple, brief procedures such as myringotomy and tube placement to much more involved procedures such as skull-based surgery. These procedures are best divided into external ear procedures (e.g., removal of exostoses or foreign bodies), middle ear procedures (e.g., myringotomy, tympanoplasty, stapedectomy), mastoid operations (e.g., mastoidectomy), and inner ear procedures (e.g., cochlear implant placement). In such procedures, and especially with inner ear procedures, patients are particularly prone to PONV.

Although many simple procedures can be performed in well-selected individuals by using local anesthesia and intravenous sedation, more complex procedures, especially those requiring an operating microscope (for which immobility is essential), are usually best accomplished using general anesthesia with the presence of a secure airway. Regardless, in all such cases the anesthesiologist must consider issues such as the appropriate form of airway management, whether nitrous oxide is contraindicated, the possibility that postintubation muscle relaxants should be avoided to permit facial nerve monitoring, and the possible need for antiemetic prophylaxis. Most patients require a tracheal tube; the unkinkable, wire-reinforced variety is commonly used to avoid airway trouble following head rotation. Alternatively, preformed tracheal tubes (e.g., RAE tubes) are commonly used.

Nitrous oxide is avoided in middle ear procedures because it diffuses from blood to the middle ear, thereby increasing middle ear pressure and potentially distending any carefully placed tympanic membrane grafts. However, many ENT surgeons now use “underlay” grafts, in which increased middle ear pressures can actually help hold the graft in place, as opposed to older “overlay” grafts, in which a high middle ear pressure would dislocate the graft.

Many middle ear operations are performed to ameliorate hearing loss from infection or inflammation. The most frequent of these procedures, myringotomy with tube placement, is most commonly performed in children by using simple sevoflurane mask anesthesia, in conjunction with acetaminophen or (less commonly) fentanyl to treat postoperative pain. The procedure can usually be safely accomplished without establishing intravenous access.

Stapedectomy, typically performed to treat otosclerosis, is usually performed using general anesthesia and may involve the use of surgical lasers (hence a potential need for laser precautions), as well as facial nerve monitoring (hence a potential need for periods with minimal neuromuscular blockade). The use of a volatile anesthetic in combination with a remifentanil infusion helps provide mild hypotension (which reduces blood loss), as well as surgical immobility. Nitrous oxide can theoretically be used early in the procedure, but it must be avoided later on to avoid damaging possible “overlay” grafts to the tympanic membrane. However, most clinicians simply avoid nitrous oxide entirely, to reduce the incidence of PONV. Gentle emergence, often involving a remifentanil infusion, helps avoid coughing or “bucking” with the tracheal tube present, with possible displacement of the bone prosthesis. Not surprisingly, extubation of the trachea during deep anesthesia is sometimes performed. Ossiculoplasty procedures involve similar considerations.

Common inner ear procedures include surgery to the cochlea, endolymphatic sac, and labyrinth. Patients with pathologic processes in the labyrinth and endolymphatic sac, such as patients with Meniere disease, often suffer from vertigo and hearing loss and are especially prone to PONV. In cochlear implant surgery, mastoidectomy is performed to implant the signal coupler while the electrode array is implanted into the cochlea, a procedure often taking over 4 hours. Considerations similar to those for stapedectomy apply, including the potential need for nerve monitoring, the avoidance of PONV, and gentle emergence from anesthesia. Some surgeons also request a degree of hypotension as a means to reduce blood loss.

Untreated chronic otitis media often leads to mastoiditis, tympanic membrane perforation, and damage to the ossicular chain. Additionally, the formation of a cholesteatoma (an invasive growth of keratinizing squamous epithelium) may spread into the mastoid cavity, inner ear, and even the brain to cause additional damage. When antibiotic treatment fails, mastoidectomy (removing infected material, draining subperiosteal abscesses, and reestablishing middle ear ventilation) may be indicated. Because blood loss can be substantial, controlled hypotension is sometimes requested. The nerve identification and gentle emergence issues discussed earlier often apply as well. Nitrous oxide is often avoided, at least in the later stages, because of the tympanoplasty component of the procedure.

Surgical procedures of the outer ear may be used to correct congenital and acquired malformations. Although these patients often present no special challenges, beware of patients whose malformation is part of Goldenhar syndrome or Treacher Collins syndrome because these patients frequently offer airway challenges. General anesthesia is typically employed, and postoperative pain can be substantial when a rib graft is used.