Handbook of Clinical Anesthesia
Anesthesia for Otolaryngologic Surgery
Significant obstruction and anatomic distortion caused by tumor, infection, or trauma may be present in a patient with minimal evidence of disease because clinically evident upper airway obstruction is a late sign (Ferrari LR, Gotta AW: Anesthesia for otolaryngologic surgery. In Clinical Anesthesia. Edited by Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC. Philadelphia: Lippincott Williams & Wilkins, 2009, pp 1305–1320). In the presence of tumor or infection in the airway, radiologic evaluation may be useful.
- Anesthesia for Pediatric Ear, Nose, and Throat Surgery
- Tonsillectomy and Adenoidectomy.Patients with cardiac valvular disease are at risk for endocarditis from recurrent streptococcal bacteremia secondary to infected tonsils. Tonsillar hyperplasia may lead to chronic airway obstruction, resulting in obstructive sleep apnea (OSA) syndrome, carbon dioxide retention, and cor pulmonale.
- Preoperative evaluationincludes a thorough history (antibiotics, aspirin-containing medications, sleep apnea) and physical examination (wheezing, stridor, mouth breathing, tonsillar size). In children with a history of cardiac abnormalities, an echocardiogram may be indicated.
- Anesthetic Management(Table 50-1)
- Sedative premedication should be avoided in children with OSA. Premedication often includes an antisialagogue.
- Induction of anesthesia is usually with a volatile anesthetic and nitrous oxide (parental presence is a consideration, especially with an anxious child) followed by administration of a nondepolarizing muscle relaxant to facilitate tracheal intubation.
Table 50-1 Goals of Anesthesia for Tonsillectomy and Adenoidectomy
- A specially designated laryngeal mask airway (LMA) that easily fits under the mouth gag permits surgical access while the lower airway is protected from exposure to blood during the procedure. Positive pressure ventilation should be avoided, although gentle assisted ventilation is both safe and effective if peak inspiratory pressure is kept below 20 cm H2O.
- Emergenceshould be rapid, and the child should be able to clear blood or secretions from the oropharynx. (Maintenance of a patent upper airway and pharyngeal reflexes is important in the prevention of aspiration, laryngospasm, and airway obstruction.)
- It is recommended that patients be observed for early hemorrhage for the first 6 hours and be free from significant nausea, vomiting, and pain before discharge.
- Complications(Table 50-2)
- Preoperative preparation of the patient who requires return to the operating room for surgical hemostasis includes hydration. (The practitioner should check for orthostatic changes.)
- A rapid sequence induction of anesthesia with a styletted endotracheal tube is often recommended.
- Dependable suction is mandatory because blood in the pharynx may impair visualization.
- Hospital Discharge.Patients undergoing adenoidectomy may be safely discharged on the same day after recovering from anesthesia. The trend is also to discharge patients undergoing tonsillectomy on the day of surgery.
Table 50-2 Postoperative Complications of Tonsillectomy
- After tonsillectomy, patients should be observed (for 4 to 6 hours) for early hemorrhage and be free from significant nausea, vomiting, and pain before discharge. The ability to take fluid by mouth is not a requirement for discharge. Excessive somnolence and severe vomiting are indications for hospital admission.
- Examples of patients in whom early discharge is not advised after tonsillectomy include those younger than 3 years of age and those with abnormal coagulation values, evidence of obstructive sleep disorder or apnea, presence of a peritonsillar abscess, and conditions (distance, weather, social conditions) that would prevent close observation or prompt return to the hospital.
- Peritonsillar abscess(Quinsy tonsil) may interfere with swallowing and breathing. (Symptoms and signs include fever, pain, and trismus.)
- Treatment consists of surgical drainage and intravenous (IV) antibiotic therapy.
- Although the upper airway seems compromised, the abscess is usually in a fixed location in the lateral pharynx (visualization of the vocal cords should not be impaired because the pathology is supraglottic and well above the laryngeal inlet) and does not interfere with ventilation of the patient's lungs by mask after induction of general anesthesia.
- Direct laryngoscopy must be carefully performed to minimize the risk of rupture of the abscess and spillage of purulent material into the patient's trachea.
Table 50-3 Anesthetic Considerations for Tympanoplasty and Mastoidectomy
- Ear Surgery
- Myringotomy and Tube Insertion
- Anesthesia may be provided with a volatile anesthetic and nitrous oxide.
- Recurrent upper respiratory infections (URIs) may not resolve until middle ear fluid is eradicated. Because tracheal intubation is not required, the presence of symptoms of an URI may not mandate a delay of surgery.
- Middle Ear and Mastoid
- Tympanoplasty and mastoidectomy are two of the most common procedures performed on the middle ear.
- Anesthetic Considerations(Table 50-3)
III. Airway Surgery
- Stridoris noisy breathing caused by airway obstruction (Table 50-4).
- Inspiratory stridor results from upper airway obstruction, expiratory stridor results from lower airway obstruction, and biphasic stridor is present with midtracheal lesions.
- Information indicating positions that make the stridor better or worse are helpful for positioning the patient to take advantage of gravity in decreasing airway obstruction during induction of anesthesia.
Table 50-4 Causes of Stridor
- Laryngomalacia caused by a long epiglottis that prolapses posteriorly is the most common cause of stridor in infants.
- Signs and Symptoms(Table 50-5)
- Goals of anesthesia include a quiet surgical field (coughing or straining during instrumentation with a rigid bronchoscope may result in damage to the patient's airway), use of an antisialagogue to decrease secretions that may obscure the view through the bronchoscope, and rapid return to consciousness with intact upper airway reflexes.
- In children, an inhalation induction of anesthesia is common, but IV drugs are usually administered to adults. Maintenance of anesthesia often includes a volatile anesthetic and muscle relaxant.
Table 50-5 Signs and Symptoms Specifically Examined in Patients with Stridor
- Because ventilation of the lungs may be intermittent, it is recommended that 100% oxygen be used as the carrier gas during bronchoscopic examination.
- If a rigid bronchoscope is used, ventilation of the lungs is accomplished through a side port (man-ual vs Sander's jet ventilation).
- At the conclusion of rigid bronchoscopy, an endotracheal tube is usually placed to control the patient's airway during recovery of anesthesia.
- Pediatric Airway Emergencies
- Epiglottitisis an infectious disease (caused by Haemophilus influenzae) of children (usually 2–7 years of age) and adults that can progress rapidly from a sore throat to total upper airway obstruction.
- Characteristic signs and symptoms include sudden onset of fever, dysphagia, and preference for the sitting position.
- Direct visualization of the epiglottis and sedation outside the operating room should not be attempted because total upper airway obstruction may result.
- If the clinical situation allows, oxygen should be administered by mask, and lateral radiographs of the soft tissues in the neck may be obtained.
- Children with severe airway compromise should proceed from the emergency room to the operating room accompanied by the anesthesiologist and surgeon.
- In all cases of epiglottitis, an artificial airway is established by means of tracheal intubation (Table 50-6).
- Laryngotracheobronchitis (LTB; Croup)
- LTB is usually a viral illness that occurs most often in children age 6 months to 6 years.
- The onset of LTB is more insidious than the onset of epiglottitis, with the child presenting with a low-grade fever, inspiratory stridor, and a barking cough.
- Treatment includes a cool, humid mist and oxygen, and in severe cases, nebulized racemic epinephrine and a short course of steroids.
- Foreign Body Aspiration
- This diagnosis should be suspected in any patient who presents with wheezing and a history of coughing or choking while eating.
Table 50-6 Establishment of an Artificial Airway in the Presence of Epiglottitis
- Most foreign bodies are radiolucent, and the only findings on radiography are air trapping, infiltrate, and atelectasis.
- Aspirated foreign bodies are considered an emergency requiring removal in the operating room.
- Inhalation induction of anesthesia with halothane (sevoflurane is an alternative) in oxygen may be prolonged secondary to obstruction of the airway.
- Nitrous oxide may be avoided to decrease the likelihood of air trapping distal to the obstruction.
- Spontaneous ventilation may be preserved until the location and nature of the foreign body have been determined.
- Respiratory compromise secondary to airway edema or infection is a possible complication in the postoperative period.
- Anesthesia for Pediatric and Adult Surgery
- Laser Surgery of the Airway
- Lasers provide precision in targeting lesions, minimal bleeding, and edema as well as preservation of surrounding structures and rapid healing.
- The carbon dioxide laser has particular application in the treatment of laryngeal or vocal cord papillomas and coagulation of hemangiomas.
Table 50-7 Anesthesia for Laser Surgery
- Misdirected laser beams may cause injury to the patient or to unprotected operating room personnel. (Eye goggles with side protectors should be used.)
- Laser smoke plumes may cause damage to the lungs or serve as a vehicle for spread of viral particles (possibly human immunodeficiency virus).
- Anesthetic Management(Table 50-7)
- Nasal Surgery
- Regardless of the anesthetic technique selected (general anesthesia or conscious sedation), it is likely that local vasoconstriction (topical local anesthetics, cocaine, and epinephrine) will be used.
- A moderate degree of controlled hypotension combined with head elevation serves to decrease bleeding at the surgical site.
- Maxillofacial Trauma
- Challenges to the anesthesiologist in caring for patients with maxillofacial trauma include securing the upper airway in the presence of unknown anatomic alterations, sharing the airway with the surgeon, and determining when it is safe to extubate the patient's trachea.
- In any patient with severe midfacial trauma, a fracture of the base of the skull must be considered.
- The mandible has a unique horseshoe shape that causes forces to occur at points often distant from the point of impact.
- The LeFort classification of fractures(LeFort I, II, and III) depicts the common lines of fracture of the midface.
- Neoplastic growths may occur anywhere within the airway and may achieve significant size with little evidence of airway obstruction.
- Attempted tracheal intubation may produce hemorrhage and edema, leading to airway obstruction.
VII. Upper Airway Infection
- Ludwig's angina is a septic cellulitis of the submandibular region that typically occurs in a patient who has undergone dental extraction of the second or third mandibular molars.
- Soft tissue edema coupled with upward and posterior displacement of the tongue and the frequent presence of laryngeal edema may result in upper airway obstruction.
VIII. Temporomandibular Joint Arthroscopy
- Temporomandibular joint (TMJ) pathology is often caused by spasm of the muscles of mastication secondary to chronic tension of these muscles (as an involuntary mental tension-relieving mechanism).
- Many patients with chronic TMJ dysfunction have significant psychopathology (depression, preoccupation with facial pain) and use mood-altering or tension-abating drugs.
- Nasotracheal intubation is usually chosen.
- Extracapsular extravasation of fluid used to irrigate the joint during arthroscopy may compromise the patency of the airway that manifests on tracheal extubation.
- Patient Evaluation
- Patients who have sustained facial trauma should be evaluated for other injuries (cervical spine fractures, cranial fractures, intracranial injury).
- Patients with Ludwig's angina are often septic and poorly hydrated.
- Tumors of the head and neck are usually associated with cigarette and alcohol abuse with associated abnormalities of pulmonary and hepatic function.
- Securing the Airway
- Awake tracheal intubation or tracheostomy may be indicated in patients with upper airway tumor, infection, or trauma.
- The technique of an “awake look” before a decision to induce anesthesia and administer a muscle relaxant may be misleading because skeletal muscle tone in the awake state that helps identify anatomic structures is absent after anesthesia and skeletal muscle paralysis are produced.
- After maxillofacial trauma, the ability to open the mouth may be limited because of pain, trismus, edema, or mechanical dysfunction of the TMJ.
- Pain does not influence mouth opening in an anesthetized and paralyzed patient.
- Trismus succumbs to an anesthetic and muscle relaxant unless there is fibrosis of the masseter muscles, which is possible if trismus has been present for 2 weeks or longer.
- Awake Intubation
- The airway must be anesthetized using a combination of topical anesthesia and superior laryngeal nerve block.
- Superior Laryngeal Nerve Block
- The external branch of the superior laryngeal nerve innervates the cricothyroid muscle (tensor of the vocal cords), and the internal branch provides sensory innervation from the base of the tongue to the vocal cords.
- With the patient lying supine, a 22-gauge needle attached to a syringe containing 2 mL of 2% lidocaine is introduced until it contacts the hyoid bone.
- When the needle contacts the hyoid bone, it is redirected caudad until it just steps off the bone penetrating the thyrohyoid membrane.
- After negative aspiration, the local anesthetic is injected, and the block is repeated on the opposite side.
- Complications of superior laryngeal nerve block include intravascular injection of local anesthetic solution. (The carotid artery lies just posterior to the site of needle placement for performance of the block.)
- Topical anesthesia includes local anesthetic instilled into the nose (a vasoconstrictor such as 0.5% phenylephrine should be added to shrink the nasal mucosa), mouth (nebulized in a hand-held nebulizer and inhaled by the patient), or both.
- Topical anesthesia may be applied below the level of the vocal cords by introducing a 22-gauge needle through the cricothyroid membrane and rapidly injecting 4 mL of 2% lidocaine.
- The resulting cough reflex distributes the local anesthetic along the tracheal mucosa and inferior surface of the vocal cords.
- An LMA may be useful in temporarily securing a compromised airway, and a tracheal tube (guide over a bronchoscope inserted through an LMA) is necessary to protect the airway from aspiration of blood. The LMA-Fastrach is a modification of the intubating LMA that was designed specifically for anatomically difficult airways.
XII. Lefort III Fractures
- This type of fracture may involve the cribriform plate of the ethmoid bone and cause separation of the nasopharynx from the base of the skull.
- Nasotracheal intubation introduces the risk of delivering foreign material from the nasopharynx into the subarachnoid space.
- Even positive pressure ventilation of the patient's lungs can increase pressure in the nasopharynx and force foreign material or air into the skull.
- The problems of securing the airway in a patient with a LeFort III fracture are usually obviated by performing a preliminary tracheostomy.
XIII. Anesthetic Management for the Traumatized Upper Airway
- After tracheal intubation or tracheostomy has been performed, general or IV drugs may be administered.
- Because a significant incidence of intracranial injury is associated with maxillofacial trauma, the brain must be protected from increases in intracranial pressure.
- When awake fiberoptic intubation is the preferred method of securing the airway (as in patients with
cervical spine injury), dexmedetomidine (1 µg/kg over 10 minutes followed by 0.2–0.7 µg/kg/hr) provides a moderate level of conscious sedation without causing respiratory depression or hemodynamic instability.
- When a tracheostomy has been performed, the decision at the conclusion of surgery is whether to allow spontaneous breathing or to create suitable conditions (opioids, muscle relaxants) for continued mechanical ventilation of the patient's lungs.
- After trauma, infection, or extensive oral resection for tumor, the endotracheal tube must not be removed until there is subsidence of edema (especially submandibular edema) or infection that might compromise the unprotected airway.
- An orotracheal tube may be removed over a tube changer.
Editors: Barash, Paul G.; Cullen, Bruce F.; Stoelting, Robert K.; Cahalan, Michael K.; Stock, M. Christine
Title: Handbook of Clinical Anesthesia, 6th Edition
Copyright ©2009 Lippincott Williams & Wilkins
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