Section Editor

Bradley J. Goldstein

Contributors

Benjamin F. Asher

Paul J. Carniol

Gregory L. Craft

David Goldenberg

Jerome C. Goldstein

Ron Mitzner

Rafael Antonio Portela

This book is organized into brief chapters addressing specific clinical entities. The chapters generally follow a standard format that allows readers to readily focus on their information needs. The template includes key features; epidemiology; signs and symptoms; differential diagnosis; evaluation, including history, exam, imaging, and other testing; treatment options, including medical and surgical treatments; and follow-up care. Most chapters also include suggestions for further reading. In this first chapter, we review in detail the approach to an efficient and effective otolaryngologic history and physical examination, which should be especially useful to those new to the care of such patients.

History

Endoscopic Exam

If the mirror examination does not provide an adequate assessment of the nasopharynx, hypopharynx, or larynx, a flexible fiberoptic nasolaryngoscopy is performed. Usually, the nose is decongested with oxymetazoline (Afrin, Schering-Plough Healthcare Products Inc., Memphis, TN) or Neo-Synephrine (Bayer Consumer Health, Morristown, NJ) spray. Topical pontocaine spray may be added for anesthetic. Surgilube jelly (E. Fougera & Co., Melville, NY) is helpful to reduce irritation. Antifog is applied to the tip of the flexible laryngoscope. The patient is best examined sitting upright. The tip of the scope is inserted into the nostril, and under direct vision is advanced inferiorly along the floor of the nose into the nasopharynx. If there is septal spurring or other intranasal deformities, the other nostril may be used. The nasopharynx is assessed for masses or asymmetry, adenoid hypertrophy, and infection. One can comment of the presence of anteroposterior (AP) or lateral collapse in the sleep apnea patient. The scope is then guided inferiorly to examine the base of tongue, valleculae, epiglottis, piriform sinuses, arytenoids, and vocal folds. Again, mucosal lesions, masses, asymmetries, mobility are noted. Asking the patient to cough and to phonate will reveal vocal fold motion abnormalities.

Often, laboratory studies, audiograms, or imaging studies are reviewed. These are summarized in the note after the physical exam section. Whenever possible, radiology images (CTs, MRIs) should be reviewed to confirm that one agrees with the reports.

Impression and Plan

In the documentation of the patient’s visit, the note concludes with an impression and plan. Generally, a concise differential diagnosis is given, listing the entities that are considered most relevant. A plan is then discussed, including further tests to confirm or exclude possible diagnoses as well as medical or surgical treatments that will be instituted or considered. Timing of a return or follow-up visit, if needed, is noted.

A copy of one’s note, or a separate letter, should always be sent to referring physicians.

All forms of surgery in the head and neck region require consideration of airway management, maintenance of ventilation with an adequate form of anesthesia, and prevention of concentrated oxygen in the operative field in the presence of cautery or laser. Various forms of airway management are discussed below, considering anatomy, innervation, indications, instrumentation and equipment, and clinical context. The specific situation of the difficult airway is then discussed.

Airway Anatomy

There are two physiologic entry points to the airway: the nose and the mouth. The epiglottis, located at the base of the tongue, separates the oropharynx from the hypopharynx. The larynx is made up of a cartilaginous structure supported by muscles and ligaments.

Innervation

Oral and Nasal Airways

In anesthetized patients, loss of airway tone allows the tongue and epiglottis to contact the posterior pharyngeal tissue leading to obstruction. Artificial airway devices can be placed in the nose or mouth to provide an air passage. Nasal airways carry a risk of epistaxis and should be avoided in anticoagulated patients. These devices should also be avoided in patients with basilar skull fractures to avoid intracranial penetration of the airway device. If an airway device is indicated in a lightly anesthetized patient, the nasal route is generally tolerated better.

Face Masks

The face mask is designed to contour and conform to a variety of facial features with the intention of creating an airtight seal capable of delivering gasses from the anesthesia equipment.

Laryngoscopes

The most commonly used intubating laryngoscopes by the anesthesiology team have curved (Macintosh) or straight (Miller) blades and an open-blade design. Newer fiberoptic video rigid laryngoscopes are useful, such as the GlideScope (Diagnostic Ultrasound Corporation, Bothell, WA). There are a variety of operative laryngoscopes that may be useful for intubation, such as the Holinger or Dedo laryngoscope.

Airway Assessment

A complete airway examination looks at several aspects of the airway. However, the first priority is to identify patients who may be difficult to ventilate or intubate. This is critically important: induction of general anesthesia with the subsequent inability to adequately ventilate the patient is an acute life-threatening emergency. Thus identification of a patient with a potentially difficult airway before induction will enable the operative and anesthetic team to institute an appropriate plan, backup plans, and assemble and test airway equipment ahead of time.

Fig. 1.2 Cormack & Lehane grades. Grade I: visualization of entire laryngeal aperture. Grade II: visualization of posterior part of the laryngeal aperture. Grade III: visualization of epiglottis only. Grade IV: not even the epiglottis is visible. (From Goldenberg D, ed. Acute surgical management of the airway. Oper Tech Otolaryngol Head Neck Surg 2007;18(2):73. Reprinted with permission.)

• Direct visualization of endotracheal tube passing through the vocal folds

• Carbon dioxide present in exhaled gasses in at least four consecutive breaths (positive end-tidal CO₂)

• Bilateral breath sounds

• Absence of air entry during epigastric auscultation

• Condensation of water vapor in endotracheal tube (ETT) during exhalation

• Maintenance of arterial oxygenation

• Chest x-ray with tip of ETT between the carina and thoracic inlet

Endotracheal Tube Size Recommendations

• Endotracheal tube size (mm): Age/4 + 4 for patients >2 years old.

• Length of insertion: 12 + Age/2. Add 2 to 3 cm for nasal intubation.

• Pediatrics: Uncuffed ETTs are generally used in patients <8 years old.

Types of Endotracheal Tube

• Ring-Adair-Elwyn Endotracheal Tubes. Ring-Adair-Elwyn (RAE) endotracheal tubes are preformed to fit in the nose or mouth and are commonly used in oral or pharyngeal surgery, particularly adenoidectomy or tonsillectomy. The shape prevents obstruction of the surgical field and fits surgical retractors such as the Crow–Davis retractor.

• Armored Endotracheal Tubes. These tubes are commonly used in head and neck surgery. They prevent kinking of the tube when the head is manipulated. This tube works well through a tracheotomy as it can be curved inferiorly out of the surgical field without kinking and sutured in place temporarily.

• Laser-Resistant Endotracheal Tubes. Laser-resistant endotracheal tubes are used in laser surgery, particularly treatment of laryngeal lesions. By preventing an interaction of inhaled oxygen and the laser, these tubes help prevent airway fires.

• Nerve-Monitoring Endotracheal Tubes. For thyroid surgery, a tube with contact electromyographic electrodes positioned at the level of the vocal folds permits intraoperative monitoring of recurrent laryngeal nerve integrity.

Endotracheal Intubation Procedure

• Preoperative evaluation will help determine the route (oral vs. nasal) and method (awake vs. anesthetized) for tracheal intubation.

• Equipment: laryngoscope with working light, appropriate-sized endotracheal tubes, oxygen supply, functioning suction catheter, functioning intravenous (IV) line, and anesthetic medications.

• Cricoid pressure: an assistant’s thumb and forefinger depress the cricoid cartilage downward, compressing the esophagus against the underlying vertebral body. This prevents spillage of gastric contents into the pharynx during the period of time from induction of unconsciousness to placement of the endotracheal tube in the trachea.

• Induction of anesthesia can be achieved by using IV or inhaled agents.

During intubation, possible complications include aspiration, dental damage, laceration of lips/gingiva/palate, laryngeal injury, esophageal intubation, endobronchial intubation, bronchospasm, and activation of sympathetic nervous system (elevated heart rate [HR] and blood pressure [BP]).

After intubation, possible complications include aspiration, laryngospasm, transient vocal fold incompetence, pharyngitis, or tracheitis.

• Miller (straight) blade: the tip of the blade is passed below the laryngeal surface of the epiglottis, which is then lifted to expose the vocal folds.

Regardless of the blade selected, the laryngoscope is lifted upward and forward in the direction of the long axis of the handle. The upper incisors should not be used as a fulcrum for leverage as this may damage teeth.

The vocal folds should be visualized prior to advancement of the endotracheal tube. Passing the endotracheal tube from the right, little resistance should be encountered. The balloon cuff of the endotracheal tube should pass 1 to 2 cm past the vocal folds. Once the proper position of the endotracheal tube is confirmed, it should be secured in place.

Nasotracheal Intubation

Prior to instrumentation, a vasoconstrictor (i.e., oxymetazoline) should be applied to nasal mucosa. After induction of anesthesia and mask ventilation is established the endotracheal tube can be placed.

The naris and endotracheal tube should be generously lubricated. The tube can be softened by placing it in warm water prior to induction. The tube is placed in the nose parallel to the palate, aiming inferiorly to avoid skull base injury, until a loss of resistance is encountered consistent with entrance into the pharynx.

Placement under direct visualization can be performed using a laryngo-scope and McGill forceps to direct the endotracheal tube past the glottic opening. Alternately, a fiberoptic bronchoscope can be placed through the tube and directed past the vocal folds.

Rapid-Sequence Intubation

Indications include aspiration risk (full stomach, history of gastroesophageal reflux disease [GERD], pregnancy, trauma) in a patient who does not appear to be a difficult intubation on physical examination.

Nonparticulate antacids, H2 blockers, and metoclopramide can be administered to decrease the acidity and volume of gastric contents. As with a standard intubation described above, instrumentation should be prepared and available. Preoxygenation with 100% O₂ by mask for 3 to 5 minutes or 4 maximal breaths over 30 seconds is sufficient. Once the paralytic and induction agents are administered, no further ventilation is given.

Induction is accomplished with any induction agent, and the procedure is followed immediately with the administration of a paralytic agent. As the medications are being delivered, cricoid pressure should be applied. Succinylcholine (1–1.5 mg/kg) because of its speed of onset is the drug of choice for rapid sequence induction. As soon as jaw relaxation is present, intubation should be performed. Cricoid pressure should continue until tracheal placement of the endotracheal tube is verified.

Indications include history of difficult intubation, acute infectious/inflammatory process that may involve the airway, mandibular fractures or other facial deformities, morbid obesity, and certain neoplasms involving the upper aerodigestive tract.

The indications and plan should be discussed with the patient. As with a standard intubation all necessary equipment should be available and checked prior to induction. A backup plan should be formulated should intubation be difficult, such as the creation of a surgical airway.

Preparing the airway by decreasing secretions with an antisialagogue (glycopyrrolate 0.2 mg 30 minutes before intubation) will help with visualization. If the nasal route is desired, administer 4 drops of 0.25% Neo-Synephrine to each naris to reduce bleeding. After standard monitors are placed, sedation with fentanyl, midazolam, or dexmedetomidine should be considered.

Topical anesthesia can be achieved using topical agents or nerve blocks. Topical agents include lidocaine jelly, nebulized lidocaine, nasal cocaine, or Cetacaine (Cetylite Industries, Pennshauken, NJ) spray. Regional anesthesia, either alone or in combination with topical agents, is useful in awake intubations. Each major nerve should be approached as described above.

Fiberoptic-Assisted Tracheal Intubation

Indications for a fiberoptic-assisted tracheal intubation include upper airway obstruction, mediastinal mass, subglottic edema, congenital upper airway abnormalities, immobile cervical vertebrae, and confirmation of proper double lumen ETT placement.

Nasal Technique

After vasoconstricting and anesthetizing the airway (see above), the ETT is advanced through the naris into the nasopharynx. The bronchoscope is then inserted into the ETT until the epiglottis and glottic opening are visualized. The scope is then passed through the opening until the carina is in view. While maintaining the carina in sight, the ETT is passed over the scope.

Oral Technique

A bite block should be inserted to protect the fiberoptic scope after anesthetizing the airway (see above). The tracheal tube is inserted into the oropharynx (8–10 cm) and the bronchoscope is inserted through the ETT. The epiglottis and glottic opening should be in view. The ETT is advanced over the scope as the carina is kept in view.

Transtracheal Ventilation

Transtracheal ventilation serves as a temporizing measure if mask ventilation and oxygenation become inadequate or impossible. A catheter (12- or 14-gauge) is inserted into the trachea through the cricothyroid membrane and connected to a jet-type ventilator capable of delivering gas at a pressure of 50 psi. The gas is then delivered using the hand-held jet ventilator. Ventilation is best assessed by observing chest rise and fall. It is advised that an inspiration:expiration (I:E) ratio of 1:4 is utilized.

Laryngeal Mask Airway (LMA)

Indications for the LMA

• Can be used in place of a face mask or ETT

• Can be used in place of an ETT for controlled ventilation as long as the peak pressure does not exceed 30 cm H₂ O

• Can aid in the management of difficult airways by providing ventilation or as a guide for fiberoptic intubation

Contraindications for the LMA

• Does not protect against gastric regurgitation and aspiration because it does not provide an airtight seal of the airway

Insertion of the LMA

• The backside of the LMA should be lubricated with a water-soluble lubricant.

• Unconsciousness is rendered with an induction agent of choice. Typically, propofol at doses of 2 to 3 mg/kg produces reliable jaw and pharyngeal muscle relaxation.

• With the LMA held like a pencil, it is placed into the midline of the mouth and advanced with pressure against the hard palate as it slides into the hypopharynx. When the upper esophageal sphincter is encountered resistance is felt. The LMA is then inflated.

• When placed properly, the black vertical line on the back of the LMA faces backward toward the head of the patient.

• The LMA is then removed upon emergence when the patient can follow commands.

Complications of the LMA

• Possible regurgitation/aspiration

• Negative pressure pulmonary edema can result when placed improperly in a spontaneously breathing patient.

• LMA malfunction in patients with pharyngeal or esophageal disease.

• Placement requires neck extension, which is often contraindicated with cervical spine disease.

The GlideScope

The GlideScope is a video laryngoscope that can be a useful alternative to the fiberoptic scope for placement of an endotracheal tube if a difficult airway is expected. The blade is curved like the Macintosh blade with a 60-degree curvature to match the anatomic alignment. The GlideScope has a digital camera incorporated in the blade, which displays a view of the vocal folds on a monitor. Under visualization on the monitor, an endotracheal tube is passed between the vocal folds.

Closed cylinder-style rigid laryngoscopes with bright fiberoptic light guides such as the Dedo or Holinger are used by the otolaryngologist and have advantages that permit visualization of the glottis and intubation.

The Difficult Airway

Fig. 1.5 Cricothyroidotomy. The airway is entered through an incision of the cricothyroid membrane. In this illustration, a trocar through a tracheotomy tube is used; a no. 15 blade will also suffice. (From Probst R, Grevers G, Iro H. Basic Otorhinolaryngology: A Step-by-Step Learning Guide. Stuttgart/New York: Thieme; 2006:379.)

A percutaneous dilation tracheotomy is not to be used in an emergent airway situation: this procedure is only to be performed on patients who are already intubated. Percutaneous bedside dilation tracheotomy has become a safe alternative to elective open tracheotomy in many ICUs. There are several different techniques all widely based on the Seldinger technique (needle and catheter over guide wire). Indications for a percutaneous dilation tracheotomy (PDT) are identical to those used for a routine open operative tracheotomy. The most common indication is prolonged intubation, mechanical ventilation. However, particular attention should be paid to potential contraindications. Some absolute contraindications for the performance of a PDT are the need for emergency tracheotomy (i.e., an emergent airway), or in a population of infants and children. Relative contraindications include poor neck landmarks, morbid obesity, previous neck surgery, limited neck extension, and severe coagulopathy that is not correctable. Other relative anesthetic contraindications include high positive end expiration pressure (PEEP >18 cm), high airway pressure (>45 cm), high FiO₂ requirement (>80%), retrognathic mandible with limited view of the larynx, and an inability to reintubate.

An appropriate percutaneous tracheotomy kit (i.e., Ciaglia or Griggs kit) and a video bronchoscope are needed to perform this procedure. At least two persons are needed: one to perform the tracheotomy, the other to manage the endotracheal tube and video bronchoscope.

• Percutaneous Dilation Tracheotomy Technique. A shoulder roll is placed beneath the patient’s shoulders and a bronchoscopist should perform simultaneous bronchoscopy through the endotracheal tube during the procedure. An incision is made either horizontally or vertically between the cricoid and the suprasternal notch and an introducer needle is placed into the trachea at about the second ring; this is confirmed with bubbling of air and with simultaneous video bronchoscopy. In addition, transillumination of light from the bronchoscope can be used to help demarcate the best site for the introducer needle. The needle is withdrawn and the overlying plastic cannula is left in place. A J-tipped guide wire is then placed under direct visualization through the catheter into the trachea. Again, every step should be bronchoscopically visualized on the video monitor during the procedure. Dilation is then performed using the provided dilator over the guide wire. This is removed and once dilation of the anterior tracheal wall has been performed, a percutaneous tracheotomy appliance is placed over the guide wire and positioned in the airway. Following this, the bronchoscope should be withdrawn from the endotracheal tube and introduced via the tracheotomy tube to confirm placement in the airway. The placement is confirmed by visualization of the carina. The tracheotomy tube is connected to the anesthesia circuit to confirm bilateral breath sounds and end-tidal CO₂. It is then secured using four sutures on all corners of the flange and a tracheotomy tie is also used to secure the appliance around the neck. Only then can the orotracheal tube be fully removed.

Criteria for Extubation

• Respiratory rate (RR)<30 per minute

• Tidal volume (TV) >5 mL/kg

• Vital capacity (VC) >10 mL/kg

• Negative inspiratory force (NIF) > −_{20 cm H}2 O

• Tidal volume/respiratory rate (TV/RR) >10

• _PaO2 >_{70 mm Hg (40% fraction of inspired oxygen [FiO}2 ])

• _PaCO2 <50 mm Hg

• Level of consciousness (LOC) stable or improving

• Ventilation, dead space/tidal volume ratio (Vd/Vt) <0.6

Further Reading

Caplan RA, Benumof JL, Berry FA, et al. 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(3):597–602

Fowler RA, Adhikari NKJ, Scales DC, Lee WL, Rubenfeld GD. Update in critical care 2008. Am J Respir Crit Care Med 2009;179(9):743–758

Goldenberg D, ed. Acute surgical management of the airway. Oper Tech Otolaryngol Head Neck Surg 2007;18(2):71–160

Hsiao J, Pacheco-Fowler V. Videos in clinical medicine: cricothyroidotomy. N Engl J Med 2008;358(22):e25

Many of the structures of the head and neck are deep and inaccessible to direct visualization, palpation, or inspection. Therefore, valuable information may be obtained by the use of various radiographic techniques. Technologic advances have replaced simple x-ray procedures with computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and positron emission tomography (PET). Other imaging modalities, such as angiography, are used for specific conditions such as vascular lesions.

Computed Tomography

A contrast-enhanced CT scan is typically the first imaging technique used to evaluate many ear, nose, throat, and head and neck pathologies. The CT scan is an excellent method for staging of tumors and identifying lymphadenopathy. A high-resolution CT scan may be used in cases of trauma of the head, neck, laryngeal structures, facial bones, and temporal bone. Temporal bone CT is used to assess middle ear and mastoid disease; paranasal sinus CT is the gold standard test for assessing for the presence and extent of rhinosinusitis. A CT scan is superior to MRI in evaluating bony cortex erosion from tumor. A CT scan is also widely used for posttreatment surveillance of head and neck cancer patients.

Fig. 1.6 Working principle of computed tomography. The x-ray tube rotates continuously around the longitudinal axis of the patient. A rotating curved detector field opposite to the tube registers the attenuated fan beam after it has passed through the patient. Taking into account the tube position at each time point of measurement, the resulting attenuation values are fed into a data matrix and further computed to create an image. (From Eastman GW, Wald C, Crossin J. Getting Started in Clinical Radiology: From Image to Diagnosis. Stuttgart/New York: Thieme; 2006:9. Reprinted with permission.)

Source: Eastman GW, Wald C, Crossin J. Getting Started in Clinical Radiology: From Image to Diagnosis. Stuttgart/New York: Thieme; 2006:9. Reprinted with permission.

Contrast Media

Working Principle of Ultrasound

Fig. 1.7 Working principle of ultrasonography. (From Eastman GW, Wald C, Crossin J. Getting Started in Clinical Radiology: From Image to Diagnosis. Stuttgart/New York: Thieme; 2006:11. Reprinted with permission.)

An esophagram (also known as a barium swallow) is designed to evaluate the pharyngeal and esophageal mucosa; it is distinct from a modified barium swallow (MBS), which evaluates laryngotracheal aspiration and is usually performed in conjunction with a speech pathologist. These techniques are performed utilizing fluoroscopy. Fluoroscopy with intraluminal contrast is invaluable for studying the functional dynamics of the pharynx and esophagus.

An MBS evaluates the coordination of the swallow reflex. It is most often used to determine the etiology and severity of airway aspiration. A speech pathologist is usually in attendance and administers barium suspensions of varying thickness (thin liquid, thick liquid, nectar, paste, and solid) while the radiologist observes fluoroscopically in the lateral projection. One can also assess for esophageal motility/dysmotility, Zenker diverticulum, stricture, mass, hiatal hernia, or obvious free reflux.

Contrast Media

Barium suspension is the most commonly used fluoroscopic contrast agent. If a perforation of the hypopharynx or esophagus is suspected there is a risk for barium extravasation into the soft tissues of the neck and/or chest. Therefore, in these cases, water-soluble contrast agents are used (such as Gastrografin, Bracco Diagnostics, Inc., Princeton, NJ). It is important to note that these agents may cause a chemical pneumonitis or severe pulmonary edema if aspirated into the airway.

Nuclear Medicine Imaging

Positron Emission Tomography with Computed Tomography

PET-CT is essentially a positron emission tomography scan performed and superimposed upon a simultaneous computed tomography scan to allow precise correlation between increased function (enhanced cellular activity) and anatomic evaluation provided by the CT. The PET scanning portion is a functional imaging technique that measures metabolic activity through the use of tagged nuclear isotopes such as a glucose precursor. ¹⁸F-fluoro-deoxyglucose (FDG) is the most commonly used radiotracer and has a half-life of ~110 minutes.

Working Principle of PET-CT

After being emitted from the atom, the positron travels in the tissue for a short distance until it encounters an electron and forms a positronium, which immediately annihilates (converts its mass to energy) forming two photons. These annihilation photons travel away from each other at 180 degrees and are picked up by the detectors placed around the patient. Simultaneous detection of these photons relates them to the same annihilation event and allows spatial localization. Annihilation detection is accomplished by dedicated PET scanners, which yield spatial resolution and sensitivity. The spatial resolution of the final reconstructed images is limited by the number of collected events.

¹⁸F is cyclotron produced and has a half-life of 110 minutes. Tumor concentration of FDG generally peaks at 30 minutes, remains constant for 60 minutes, and then declines.

Note that FDG can also accumulate nonspecifically in other cells that have active glycolysis such as areas of active inflammation and infection. This may lead to a false-positive PET-CT scan. Other activities that may cause false-positive findings include muscular activity, foreign bodies, and granulomas. False-negatives in PET-CT scans may occur when the tumor threshold is too small (<0.5 cm in diameter). In PET scanning, quantification of FDG uptake intensity is generally expressed on an arbitrary scale as standard uptake values (SUVs).

Thyroid Scintigraphy

Thyroid scintigraphy renders, at one point in time, information about the global and regional functional status of the thyroid. It is observer-independent and reproducible with low inherent radiation exposure. Scintigraphic imaging of the thyroid helps determine whether solitary or multiple nodules are functional when compared with the surrounding thyroid tissue. Findings for a nodule may be normal functional (warm), hyperfunctional (hot), or hypofunctional (cold). Scintigraphy can also help determine whether cervical masses contain thyroid tissue, and it can demonstrate whether metastases from well-differentiated thyroid cancer concentrate iodine for the purpose of radioiodine therapy. For thyroid scintigraphy the following radionuclides are in use: technetium-99m (^99mTc), ioflupane (¹²³ I), and iodine-131 (¹³¹I).

Working Principle of Thyroid Scintigraphy

The technique of thyroid scintigraphy is based on the principle that functional active thyroid cells incorporate iodine.

Parathyroid Scintigraphy

Several radiotracers are available for parathyroid scintigraphy. At present, the radiotracer of choice is ^99mTc-sestamibi (aka sestamibi, methoxyisobutylisonitrile, or MIBI). ^99mTc-sestamibi is a lipophilic cation that is taken up in the mitochondria of the cells. Of note, this radiotracer can be used with a wide variety of imaging techniques including planar MIBI, single proton emission computed tomography (SPECT), and fused SPECT-CT.

Sestamibi accumulates in the thyroid and parathyroid tissues within minutes after IV administration, but it has a different washout rate from these two tissues. It is released faster from the thyroid than from the parathyroid. The presence of large numbers of mitochondria-rich cells in parathyroid adenomas is thought to be responsible for their slower release of ^99mTc-sestamibi from hyperfunctioning parathyroid tissue versus the adjacent thyroid tissue. Thus, on 2- to 3-hour washout images, after thyroid uptake has dissipated, the presence of a retained area of activity allows one to identify and localize a parathyroid adenoma. Overall, ^99mTc-sestamibi parathyroid scintigraphy has good sensitivity for the detection and localization of a single adenoma in patients with primary hyperparathyroidism. Correlation with ultrasound findings can also be helpful.

Single Proton Emission Computed Tomography

SPECT scanning for parathyroid disease allows increased accuracy of routine sestamibi scanning by ~2 to 3%. SPECT scanning can be performed within the first several hours after a patient is injected with the sestamibi. During the scan, multiple images are taken of the patient’s head and neck. These images are assimilated to provide a three-dimensional picture. SPECT scanning is typically used when ordinary planar sestamibi scans are inconclusive.

Further Reading

Eastman GW, Wald C, Crossin J. Getting Started in Clinical Radiology: From Image to Diagnosis. Stuttgart/New York: Thieme; 2006

Mafee MF, Valvassori GE, Becker M. Imaging of the Head and Neck. 2nd ed. Stuttgart/New York: Thieme; 2005

Moedder U, Cohnen M, Andersen K, Engelbrecht V, Fritz B. Head and Neck: Direct Diagnosis in Radiology. Stuttgart/New York: Thieme; 2008

Modes of Anesthesia

• General anesthesia: characterized by total loss of consciousness with blunted (or absent) protective upper airway reflexes and the use of an endotracheal tube or supraglottic device (e.g., laryngeal mask airway).

• Sedation: aims to maintain protective upper airway reflexes in patients with iatrogenic altered levels of consciousness. Supplemental oxygen is often required (e.g., nasal cannula), with or without the assistance of an oral/nasopharyngeal airway. It can range from minimal (i.e., patient is responsive to verbal command) to deep (i.e., no response to procedural stimulation).

• Regional anesthesia: involves the use of local anesthetics in conjunction with sedation or general anesthesia to improve analgesia, expedite recovery, and reduce overall IV/inhalational anesthetic requirements. It can be used as a sole anesthetic for minor or superficial procedures.

An ideal anesthetic strikes a balance between the following four essential factors, which in turn are influenced by independent patient risk factors, unique surgical requirements, and circumstances under which recovery is to occur.

• Amnesia/anxiolysis: management of preoperative anxiety and control of intraoperative awareness is a cornerstone of anesthetic care. Various oral, IV, and/or inhalational agents may be used, depending on the desired effect.

• Analgesia: multimodal therapy is the preferred method of achieving intra- and postoperative pain control with a combination of narcotics, nonsteroidal antiinflammatory drugs (NSAIDs), local anesthetics, and/or adjutants [e.g., gabapentin, Ketamine (Pfizer Pharmaceuticals, New York, NY), clonidine].

• Muscle relaxation: depolarizing and/or nondepolarizing muscle relaxants facilitate optimal airway conditions for laryngoscopy and surgical manipulation.

• Antiemetics: postoperative nausea and vomiting (PONV) is a strongly undesirable complication in patients following head and neck surgery. High-risk procedures include otology surgery, adenotonsillectomy, thyroidectomy, as well as head and neck cancer surgery. PONV influences patient satisfaction, length of stay, recovery, and surgical outcome. Multimodal and prophylactic therapy improves outcomes. Emesis may predispose development of wound hematoma, which can become an airway emergency in the presence of a neck wound.

Phases of Anesthesia

• Preinduction: begins in the preoperative area and continues to the point where a patient is positioned on the operating room table with standard monitors (electrocardiogram [ECG], noninvasive blood pressure, pulse oximetry, capnography) and has been adequately preoxygenated.

• Induction: general anesthesia in patients with established IV access is initiated with rapid-acting parenteral drugs to facilitate airway control. Otherwise, inhalational anesthetics are administered via a face-mask; once an adequate depth of anesthesia is achieved, IV access is established and is followed by the placement of an endotracheal tube or supraglottic device (unless a very brief procedure is planned). For sedation cases, IV agents are titrated to effect while maintaining spontaneous ventilation. For difficult airway situations, awake fiberoptic nasotracheal intubation or awake tracheotomy may be indicated to secure the airway, prior to induction of general anesthesia.

• Maintenance: global amnesia is maintained during surgery with inhalational agents and/or parenteral drug infusions. Surgical analgesia is maintained either with a well-established regional block, generous local anesthetic infiltration, intermittent opioid boluses, and/or IV narcotic infusion. Duration of required muscle paralysis depends on several factors, and may be just long enough to facilitate endotracheal tube placement. In some instances (e.g., cases involving extensive neuromonitoring), anesthesia may be maintained through the predominant or exclusive use of parenteral infusions (total intravenous anesthesia [TIVA]). TIVA is sometimes useful to reduce vasodilation and bleeding, i.e., in endoscopic sinus surgery.

• Emergence: extubation upon meeting criteria

• Stage 4: massive anesthetic overdose that causes severe depression of brainstem activity leading to respiratory and/or cardiovascular collapse. This stage should never be reached as it may be lethal even with appropriate cardiovascular and/or respiratory support.

Further Reading

Barash PG, Cullen BF, Stoelting RK, et al. Clinical Anesthesia. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009

Morgan GE, Mikhail MS, Murray MJ. Clinical Anesthesiology. 4th ed. New York:McGraw-Hill Medical; 2005

Benefits of Regional Anesthesia

When combined with a general anesthetic, regional nerve blocks reduce narcotic requirements and their subsequent side effects such as nausea, vomiting, somnolence, and respiratory depression. Time to discharge is reduced.

Contraindications to Regional Anesthesia

Contraindications to regional anesthesia include lack of patient consent and interference with surgical field/technique. Relative contraindications include coagulopathy, infection at the skin site, and presence of neurologic disease.

Complications Common to All Nerve Blocks

Complications common to all nerve blocks include local anesthetic complications (intravascular injection, overdose, and allergic reaction), nerve damage (needle trauma, intraneural injection), and hematoma.

Blocks of the Scalp and Face

Supraorbital and Supratrochlear Nerve

Indications: closure of lacerations, forehead, and ear procedures

The forehead and anterior scalp can be rendered insensate by blocking the supraorbital and supratrochlear branches of the ophthalmic division of the trigeminal nerve where they exit from their respective foramina along the brow line.

A skin wheal is placed over the glabella. A 25-gauge needle, bent to aid in superficial placement, is inserted through the anesthetizing wheal and advanced laterally along the brow. A total of 8 mL of local anesthetic is applied from the glabella to the lateral edge of each brow.

Indications: closure of lacerations

By blocking the greater and lesser occipital nerves, the posterior scalp can be anesthetized. By placing a track of local anesthetic from the mastoid process to the inion (i.e., external occipital protuberance) along the highest nuchal line from each side, both the greater and lesser occipital nerves will receive a dose of local anesthetic and the posterior scalp will become anesthetized.

A large skin wheal is placed over the mastoid process on each side using a 27-gauge needle. Then through this wheal, a wheal is placed from the mastoid process to the inion using a 25-gauge Quincke needle that is bent to facilitate a superficial injection.

Infraorbital Nerve

Indications: closure of lacerations, facial surgery

The maxillary division of the trigeminal nerve innervates the midface, from the inferior portion of the orbit to the mandible. This area includes the area overlying the zygoma, the maxilla, and most of the nose, as well as the philtrum and the hard and soft palate.

The infraorbital foramen is palpable 2 to 3 mm below the rim of the orbit, just medial to the equator of the orbit. A small-gauge needle is used to inject local anesthesia just outside the foramen. Avoid injection into the foramen as the nerve is located in a confined space.

A small amount (2–4 mL) of local anesthetic is sufficient and it should be injected based on which area is to be anesthetized, i.e., emphasize above the foramen for lower lid work, medial to the foramen for lateral nasal work, and inferomedial to the foramen for work on the philtrum.

Blocks of the Neck

Superficial Cervical Plexus

The cervical plexus is composed of four nerve roots, C₁ –C₄, and terminates in four branches: lesser occipital, great auricular, transverse cervical, and supraclavicular nerves. The terminal branches emerge superficially at the posterior border of the sternocleidomastoid (SCM) muscle along the mid-portion of the muscle.

This is a purely cutaneous nerve block; there is no motor block with the superficial cervical plexus block. Neuromonitoring and stimulation of the recurrent laryngeal nerve is not compromised when using this block.

The patient is positioned in the seated position. A line connecting the insertion of the SCM at the midpoint of the clavicle to the mastoid process along the posterior muscle border designates the path in which subcutaneous local anesthetic should be injected. Initially, 3 to 5 mL of local anesthetic is injected at the midpoint of the SCM using a 27-gauge needle. Using a 25-gauge Quincke point spinal needle, subcutaneous injections are then performed from this initial injection site in caudad and cephalad directions along the posterior edge of the SCM. Infiltration along these paths should require 6 to 8 mL of anesthetic in each direction. Aspiration prior to injection is important to avoid intravascular injection.

The deep cervical plexus (DCP) is the collection of the C₂ –C₄ nerve roots as they exit the “gutter” formed by the transverse process of the respective vertebrae. By injecting prior to the division of the cervical roots into dorsal and ventral spinal nerves, a more complete blockade of the ipsilateral neck is achieved—including both sensory and motor elements. This is not commonly used for otolaryngology procedures.

The patient is seated upright in a high Fowler position with a small towel behind the shoulders. The above-mentioned line is drawn between the mastoid process and the anterior tubercle of C₆, which is palpable in the vast majority of patients. A line parallel to this is drawn 1.5 cm behind the first, and the posterior tubercle is palpated on C₂, C₃, and C₄. Deep palpation can be uncomfortable and a light touch is indicated. After a small skin wheal with a 27-gauge needle, a short (2.5 cm) blunt needle is advanced to the posterior process of each of the three vertebrae and then “walked” laterally and anterior to the posterior tubercle. An advance of 1 mm beyond the bony tubercle will suffice. It is not uncommon for the patient to describe a light paresthesia in the dermatome of the root being blocked. After careful aspiration, 4 to 5 cc of local anesthetic (with epinephrine) is injected at each of the three levels. (C₂, C₃, C₄). The proximity to the spinal column and major vascular structures increases the risk of intrathecal or intravascular injection.

Specific Nerve Blocks for the Upper Airway

Maxillary Division of the Trigeminal Nerve (Sphenopalatine Ganglion)

• The transnasal topical approach to the sphenopalatine ganglion involves application of local anesthetic to the mucous membranes surrounding the ganglion.

• Position the patient supine with neck extension. A local anesthetic (typically 80 mg of 4% cocaine) is applied to each nostril. Cotton-tipped applicators soaked in 4% cocaine are gently swirled and advanced into the nares. Each applicator is advanced a little further than the one prior, and once placed the applicator is left there as successive applicators are introduced. Each nostril should receive four to seven applicators as the opening allows. The applicators should remain in the nares for at least 20 minutes allowing the local anesthetic to diffuse through the mucosa overlying the ganglion.

• The sphenopalatine ganglion can also be approached through the greater palatine foramen located at the posterior portion of the hard palate. In this approach, the patient is positioned in the supine position with the neck extended. The foramina can be palpated medial to the gumline of the third molar. A small-gauge needle is advanced <2.5 cm through the foramen in a superior and slightly posterior direction. To avoid an intravascular injection, aspirate prior to injection.

• The glossopharyngeal nerve (CN IX) exits the skull at the jugular foramen and passes between the internal jugular vein and the internal carotid artery. It descends just dorsal to the styloid process before curving forward and anterior to innervate the palatine tonsil, the mucous membranes of the fauces and the base of the tongue. This nerve has motor, sensory, and autonomic components, and supplies lower motor neurons to the stylopharyngeus and parasympathetic innervation of the parotid and mucous glands.

Superior Laryngeal Branch of the Vagus Nerve

• The superior laryngeal nerve can be blocked as it passes into the thyrohyoid membrane inferior to the greater cornu of the hyoid bone and superior to the greater cornu of the thyroid cartilage. This block will provide anesthesia to the glottis above the vocal folds.

• With the patient seated in an upright (high Fowler position) with a towel roll transversely laid behind the shoulders, the thyroid cartilage is palpated. It can be helpful to lightly displace the thyroid cartilage toward the side of the block. Using a small-gauge needle, 2 to 3 mL of local anesthetic is injected near the cartilaginous greater cornu. Aspiration prior to injection will confirm that the needle has not entered the supraglottic air column. This procedure is then repeated on the other side.

Topical Anesthesia of the Subglottic Airway

• The recurrent laryngeal branch of the vagus nerve pierces the subglottic trachea to innervate all the laryngeal muscles other than the cricothyroid muscle as well as provide sensory innervation to the subglottic mucosa.

• The patient is positioned in a high Fowler position with a towel roll laid transversely behind the shoulders. Moderate neck extension is helpful. After skin disinfection, the thyroid cartilage is identified. The next palpable cartilage inferiorly is the cricoid cartilage. The palpable gap between these two structures overlies the cricothyroid membrane. A 22-gauge needle containing local anesthetic (2 to 4 mL 3% chloroprocaine or 2 to 4 mL 4% lidocaine) is advanced perpendicular to the skin while gentle aspiration is applied to the syringe plunger. Air will be freely aspirated when the needle penetrates the cricothyroid membrane, entering the trachea. The patient should be alerted that the injection will induce coughing. The local anesthetic should be rapidly administered and the needle withdrawn. The patient will cough and should be encouraged to do so several times to enhance spread of the anesthetic.

Further Reading

Barash PG, Cullen BF, Stoelting RK, et al. Clinical Anesthesia. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009

Morgan GE, Mikhail MS, Murray MJ. Clinical Anesthesiology. 4th ed. New York: McGraw-Hill Medical; 2005

Opioids

Flumazenil

Flumazenil is a specific benzodiazepine receptor antagonist that reverses most of the effects of benzodiazepines. Onset is rapid (<1 minute) for the hypnotic effects of benzodiazepines. The amnestic effect is less reliably reversed. This agent is a competitive inhibitor at the benzodiazepine receptor. Elderly patients in particular are prone to resedation and should be observed for respiratory depression after flumazenil administration.

Dosing: 0.2 mg (titrate every minute until desired degree of sedation reversal is observed). Sedation reversal typically requires 0.6–1.0 mg. Infusions at 0.5 mg/h are indicated for overdoses of long-acting benzodiazepines.

Alpha-2 Agonists

Dexmedetomidine

Dexmedetomidine (brand name Precedex, Hospira, Inc., Lake Forest, IL) is an β2 agonist with 8 to 10 times greater receptor affinity than clonidine. It has sympatholytic, analgesic, and sedating properties. The effect on the cardiovascular system is to lower heart rate and blood pressure, blunting the typical surgical response. β2 Agonists have minimal respiratory depression. Head and neck surgeons will find this drug useful for conscious sedation cases, augmented sleep studies, and fiberoptic intubations and tracheotomy placement. Also of interest to the otolaryngologist who employs the use of topical cocaine intraoperatively, recent research has suggested dexmedetomidine to be an effective treatment for the dangerous cardiovascular symptoms of cocaine intoxication.

Dosing: Loading dose of 1 μg/kg over 10 minutes followed by IV infusion at 0.2–0.7 μg/kg per hour

Anesthesia Induction Medications

Propofol

Barbiturates have several sites of action resulting in suppression of excitatory neurotransmitters and activation of the inhibitory effects of GABA. The result is inhibition of the reticular activation system. Methohexital and thiopental are the commonly used barbiturates used for induction. As more titratable induction agents have come into use, barbiturates have fallen out of favor. Barbiturates have no analgesic properties and cause dose-related depression of the respiratory, cardiac, and central nervous systems. Thiopental has a short duration of action secondary to a high rate of redistribution from the brain to inactive tissues, which secondary to a high lipid solubility. Barbiturates are contraindicated in patients with intermittent porphyria. Side effects include venous irritation, myoclonus, and hiccupping.

Dosing: Thiopental 3–6 mg/kg IV; methohexital 1–2 mg/kg IV

Inhaled Anesthetics

In the OR, general anesthesia is commonly maintained with inhaled anesthetics. These agents also provide some analgesia, amnesia, and muscle relaxation. In pediatric patients in whom there is no IV access, anesthesia may be induced by inhalation. All of the inhaled anesthetics, with the exception of nitrous oxide, are bronchodilators and may be useful in those with reactive airways. Most inhaled agents reduce blood pressure. The onset of anesthetic induction as well as emergence from anesthesia is based on the lipid solubility characteristics of the inhaled anesthetic: the more insoluble the anesthetic agent, the faster the induction of anesthesia. The agents with high lipid solubility prolong the emergence from anesthesia.

Minimum alveolar concentration (MAC) is defined as the alveolar concentration at which 50% of test subjects will not respond to a surgical stimulus. Dosing of inhaled agents is based on the MAC of each particular agent. The MAC of inhaled agents depends on the individual gas properties of each agent. MAC is additive such that ½ MAC isoflurane combined with ½ MAC nitrous oxide is equivalent to one MAC of sevoflurane.

Isoflurane

Key Features