Anesthesia For Ear, Nose, Throat & Maxillofacial Surgery (PDF)

Anesthesia for Ear, Nose, Throat, and Maxillofacial Surgery Part III PROCEDURES INVOLVING THE FACE, EAR, HEAD, AND NECK Prof. Albert J. Albors DNP, CRNA, APRN University of Puerto Rico Medical Sciences Campus Nurse Anesthesiology Program 1 Objectives • Describe the pertinent anatomy and physiolo...

Anesthesia for Ear, Nose, Throat, and Maxillofacial Surgery Part III PROCEDURES INVOLVING THE FACE, EAR, HEAD, AND NECK Prof. Albert J. Albors DNP, CRNA, APRN University of Puerto Rico Medical Sciences Campus Nurse Anesthesiology Program 1 Objectives • Describe the pertinent anatomy and physiology of the head and neck for the anesthetist. • Reviews specialized anesthetic considerations, reviews surgical and anesthesia equipment used during ENT procedures. • Analyzes some of the common pharmacologic agents used for ENT procedures. • Discuss principles of anesthesia for ENT. 2 Some of the common surgical procedures for the ear and face include myringotomy with insertion of tubes, mastoidectomy, acoustic neuroma, stapedectomy, and tympanoplasty. Introduction During ear surgery the anesthetist must be concerned with four major issues: 1. nerve preservation 2. the effect of N2O on the middle ear 3. control of bleeding 4. PONV 3 Nerve preservation during surgical procedures Intraoperative neuromonitoring is a relatively recent advance in electromyography (EMG) applied to head and neck surgery. Its purpose is to allow real-time identification and functional assessment of vulnerable nerves during surgery. The nerves most often monitored in head and neck surgery are: • the motor branch of the facial nerve (VII) • the recurrent or inferior laryngeal nerves (X) • the vagus nerve (X) • the spinal accessory nerve (XI) • other lower cranial nerves monitored less frequently 4 5 Nerve preservation during surgical procedures • Muscle relaxants should only be used at induction and intubation to prevent interference with the nerve monitoring. • The use of local anesthetics is also contraindicated because of their suppressant effects on muscle action potential amplitudes and muscle movement. • The use of volatile anesthetic agents and N2O is acceptable only if the N2O is discontinued well before closing any cavity. • Midazolam preoperatively helps assure amnesia and rapid emergence. • Selected use of deep extubation helps prevent straining during emergence, as straining increases postoperative bleeding and may necessitate reexploration. 6 Middle ear procedures • The term middle ear refers to the air-filled space between the tympanic membrane and the oval window. • The middle ear contains three ossicles—the malleus, incus, and stapes which transmit sound vibration from the eardrum to the cochlea. • This air-filled cavity is traversed by the facial nerve before it exits the skull via the stylomastoid foramen. The facial nerve provides motor innervation to the muscles of facial expression. • Common surgeries in adults include tympanoplasty, stapedectomy and mastoidectomy. • Common middle ear surgery in children includes tympanoplasty, mastoidectomy, myringotomy, grommet insertion, and cochlear implantation. 7 Middle ear procedures • Middle ear surgery can be accomplished with either local or general anesthesia depending on the patient’s ability to cooperate. • When general anesthesia is chosen, the airway can be maintained with a LMA or endotracheal intubation. • A nerve stimulator is often employed for intraoperative monitoring of evoked facial nerve EMG activity to aid preservation of the facial nerve. • Muscle relaxants are therefore avoided after intubation. • A smooth recovery without coughing or straining is important to prevent prosthesis displacement, especially in patients who have undergone reconstructive middle ear surgery. 8 Middle ear procedures • PONV, a common problem after middle ear surgery, can be minimized by the appropriate choice of anesthetic technique and antiemetic prophylaxis. • Physical and pharmacologic techniques are used to minimize bleeding. They include a head-up tilt of 15 to 20 degrees, avoidance of venous obstruction, normocapnia, and controlled hypotension. An ideal systolic blood pressure range is 80 to 90 mm Hg or a reduction of MAP to 20% of baseline in patients with hypertension. • Pharmacologic agents used for controlled hypotension in ear, nose, and throat surgery include inhalation anesthetics, βadrenoceptor antagonists (labetalol and esmolol), α2adrenergic agonists (dexmedetomidine), opioids (remifentanil), and more recently, magnesium sulfate. 9 Nitrous oxide and middle ear surgery • Nitrous oxide is 34 times more soluble than nitrogen in blood and enters the middle ear cavity more rapidly than nitrogen leaves causing an increase in middle ear pressure if the eustachian tube is obstructed. • During tympanoplasty the middle ear is open to the atmosphere; thus, there is no buildup of pressure, but once a tympanic membrane graft is placed, the continued use of N2O might cause displacement of the graft. • Because N2O is only a supplement to general anesthesia, avoiding it altogether during tympanoplasty is more reasonable. • N2O also may increase PONV, and its use in middle ear surgery may further increase the incidence of PONV above that already associated with this type of surgery. 10 Myringotomy and tube placement • A myringotomy allows the pressure to equalize between the middle ear and the atmosphere, reducing the pressure in the middle ear compartment. • Simple tubes with a lumen (grommets) are placed through the patient’s tympanic membrane to alleviate the pressure created in the middle ear usually seen with chronic serous otitis media or recurrent otitis media. • Mask or IV induction and maintenance using oxygen, N2O, and a volatile inhalation agent such as sevoflurane is routine. • IVs are not usually necessary unless another procedure is performed at the same time. • Bilateral myringotomies with tube insertions are typically very short operations. Sedative pre-medications may outlast the procedure and are usually not necessary. • https://youtu.be/eooAt93bn6A?si=QpX8M_9EYInDImZD 11 12 Tonsillectomy and Adenoidectomy • An adenotonsillectomy, although often considered a simple procedure, has the potential for significant airway challenges. • Considerations of airway obstruction, shared airway, mechanical suspension of the airway, management of intubation and extubation, pain management, and the desire for a rapid awakening are all subtleties of anesthesia for this procedure. • Surgical approaches to tonsillectomy include coblation, cold steel, snare, monopolar cautery, and hot knife techniques. • In adult patients, a tonsillectomy may also accompany a uvulopalatopharyngoplasty (UPPP) for Pickwickian syndrome or obstructive sleep apnea (OSA). • Adult patients with severe OSA may require awake intubation before the induction of general anesthesia. 13 Tonsillectomy and Adenoidectomy • In children, anesthesia is induced most commonly with sevoflurane, oxygen, and N2O by mask depending on the age of the child and IV access. • LMA and ETT may both be used depending on the experience of the operating team. • A cuffed tube is recommended in those older than 8 to 10 years of age, with continued attention given to inflation pressures of the cuff. A properly sized pediatric ETT should allow a leak at 20 cm H2O airway pressure, which reduces the likelihood of postoperative croup and edema. • The choice of maintenance techniques for anesthesia varies. Several goals need to be considered when choosing an anesthetic: (1) provide a depth of anesthesia adequate to blunt strong reflex activity elicited by the procedure, (2) a rapid return of protective airway reflexes, (3) good postoperative analgesia, (4) reduced postoperative bleeding, and (5) minimal PONV. 14 Tonsillectomy and Adenoidectomy • Suggested techniques include modest opioids and IV acetaminophen doses for analgesia, dexamethasone and ondansetron for antiemetic prophylaxis, and deep extubation of the trachea to minimize coughing and airway stimulation when prudent. • Blood loss during tonsillectomy is difficult to assess but has been estimated to average 4 mL/kg or 5% of blood volume. • At the end of the surgical procedure the surgeon may release tension on the mouth gag to ensure that all bleeding has been controlled. The insertion of an orogastric tube and some irrigation may be used to remove blood and secretions from the stomach and oropharynx. • The patient should be transported to the recovery in the “tonsil position”—that is, on one side with the head slightly down. This allows blood or secretions to drain out of the mouth rather than flow back onto the vocal cords. • https://youtu.be/IFYGidWMq3E?si=spbpajJqQR5LrQv5 15 Bleeding Tonsil • Post-tonsillectomy hemorrhage (PTH) is the most common emergency pediatric airway surgery. Rates of PTH are between 0.5% and 7.5% and are most common in patients older than 15 years of age, male gender, patients with frequent infectious tonsillitis, and after hot (electrocautery) versus cold (scalpel) techniques. • Slow oozing of the tonsillar bed is far more common than profuse bleeding. Patients may swallow large volumes of blood before bleeding is discovered. The patient may have signs of hypovolemia evidenced by tachycardia, hypotension, and agitation. If the blood is swallowed, the patient may have nausea and vomiting. • All patients should be assumed to have a significant amount of blood in the stomach and a rapid sequence induction is indicated. • The induction agent selected is based on the hemodynamics and condition of the patient. Emergence and extubation of the trachea should occur after return of protective laryngeal reflexes. 16 Thyroid Surgery • The thyroid gland is butterfly-shaped and composed of two lobes that are connected by a median tissue mass named the thyroid isthmus. • It is located on the anterior and anterolateral aspect of the trachea immediately inferior to the larynx. The thyroid gland is the largest endocrine gland in the body weighing 20 g in the healthy adult. • Its major blood supply arises from the superior and inferior thyroid arteries, which are branches of the common carotid artery. • Motor function associated with movement of the intrinsic muscles of the larynx that abduct, adduct, and tense the vocal cords is supplied by the RLN and the external branch of the superior laryngeal nerve. 17 18 Preoperative Assessment and Preparation • The primary goals during preoperative assessment are ensuring that the patient is euthyroid, assessing the degree of end-organ complications, and determining the extent of airway involvement. • Preoperatively the patient will be taking a combination of antithyroid medications to decrease the synthesis and release of thyroid hormone, and to treat the hyperdynamic state associated with hyperthyroidism. • Patients should continue their regimen of antithyroid medications and β-blockade through the morning of surgery. • Patients with hyperthyroidism have increased T3 and T4 values and decreased or normal thyroid-stimulating hormone (TSH) levels. 19 20 Preoperative Assessment and Preparation • All routine airway assessments should be performed in addition to a full visualization and palpation of the patient’s neck for a thyroid goiter. The patient’s airway should be assessed in the supine position. • If there is any indication of potential for airway compromise, a chest radiograph and a CT scan of the neck and chest should be performed and evaluated prior to induction of anesthesia. • Patients with hyperthyroidism have a higher incidence of myasthenia gravis and may present with skeletal muscle weakness and an increased sensitivity to muscle relaxants. 21 Intraoperative Anesthetic Management • General endotracheal anesthesia is the technique of choice for thyroidectomy, and the standard induction and maintenance drugs are used. • Paralysis may inhibit the surgeon’s ability to assess the integrity of the RLN, and relaxation is avoided after intubation if nerve testing is planned. Succinylcholine is chosen for intubation because of its short duration and spontaneous degradation. • Intraoperative neural monitoring (IONM) during thyroid and parathyroid surgery has gained widespread acceptance as an adjunct to the gold standard of visual nerve identification. • A special ETT, the Medtronic nerve integrity monitor (NIM) EMG endotracheal tube (NIM 3.0 ETT), is frequently used to assess recurrent laryngeal and vocal cord function during surgery. 22 Intraoperative Anesthetic Management • The NIM 3.0 ETT is a flexible silicone elastomer ETT with an inflatable cuff. The tube is fitted with four stainless-steel wire electrodes (two pairs) that are embedded in the silicone of the main shaft of the ETT and exposed only for a short distance, slightly superior to the cuff. • The electrodes are designed to make contact with the patient’s right and left vocal cords to facilitate EMG monitoring of the muscles innervated by the RLN when connected to a four-channel EMG monitoring device. • The red wire pair of the NIM tube should contact the anterior and posterior portion of the right true vocal cord, and the blue wire pair should contact the anterior and posterior portion of the left true vocal cord. 23 24 Intraoperative Anesthetic Management • Maintenance of anesthesia can be provided by inhalational anesthetics with or without N2O. A combined deep and superficial cervical plexus block may be considered for intraoperative and postoperative pain management; additionally, IV anesthesia may also be suitable and provide optimal conditions. • The patient is positioned supine with the head elevated 30 degrees and the neck extended using a roll behind the neck and shoulders (Rose position). • The arms are tucked at the patient’s sides with the ulnar nerves padded and protected. Hyperextension of the neck should be avoided in those patients with atlantoaxial joint instability and/or those with limited range of motion. • If true hypotension occurs, it is best treated with a direct-acting vasopressor (phenylephrine) rather than an indirect-acting vasopressor (ephedrine), which stimulates the release of catecholamines. 25 26 Postoperative Management • Postoperative hypocalcemia can result from hypoparathyroidism. The four parathyroid glands are located on the posterior aspect of the thyroid gland and produce parathyroid hormone, which increases serum calcium. Inadequate release of parathyroid hormone is caused by the inadvertent removal of the parathyroid glands during a total thyroidectomy. • Patients most commonly develop signs and symptoms associated with hypocalcemia 24 to 96 hours postoperatively. • The degree of hypocalcemia coincides with the severity of the symptoms, which include perioral numbness and tingling, abdominal pain, paresthesias of the extremities, carpopedal spasm, tetany, laryngospasm, mental status changes, seizures, Q-T prolongation on the electrocardiogram, and cardiac arrest. 27 28 Postoperative Management Neuromuscular irritability also can be confirmed by assessing for: Chvostek sign-facial contractions elicited by tapping the facial nerve in the periauricular area. Trousseau sign- carpal spasm on inflation of a blood pressure cuff. 29 Postoperative Management • Treatment for severe symptomatic hypocalcemia includes the administration of calcium gluconate or calcium chloride (10 mL of 10% solution) intravenously given over several minutes and followed by a continuous infusion (1–2 mg/kg/hr) until calcium levels normalize. • Unilateral RLN damage causes the ipsilateral vocal cord to remain midline during inspiration resulting in hoarseness. • Unlike unilateral nerve injury, bilateral nerve injury necessitates immediate intervention requiring emergent reintubation or tracheotomy. • Postoperative bleeding of the surgical site results in a neck hematoma, which causes airway obstruction and asphyxiation. This complication represents a true surgical emergency. Common symptoms of neck hematoma include neck swelling, neck pain and pressure, dyspnea, and stridor. • https://youtu.be/M4UDc2jUYmE?si=qxTyUBCMYwqZ8rkV 30 Cleft Palate and Lip • A cleft develops when the bones of the nasal and maxillary or the palatal bones fail to fuse. A fetus can develop both a cleft lip and palate or either alone. Up to 30% of these newborns have other congenital anomalies such as Down syndrome, Pierre Robin syndrome, and Treacher Collins syndrome. • Intubation may sometimes be difficult if the laryngoscope blade slips into the cleft. However, packing the cleft with gauze assists I preventing this from occurring. An oral RAE tube or flexible connector is used and secured at the midline of the lower lip. • Before emergence, a suture is often placed through the tip of the tongue and taped to the cheek. This suture eliminates the need for an oral airway and prevents damage to the palatal repair. • If edema occurs, a more aggressive and immediate airway management technique should be used. Copious secretions and blood may cause laryngospasm after extubation, and therefore a clear airway is imperative. • https://youtu.be/RL3RsSGhqNs?si=vr6hqC6blSJMmls3 31 32 Dental restoration procedures • Dental restoration procedures are performed under general anesthesia for a multitude of reasons. These include multiple cavities, history of cerebral palsy or Down syndrome, and an uncooperative patient who would not be an appropriate candidate for local anesthetic and an office procedure. • In patients with normal airways a standard induction is appropriate, and a nasal intubation usually facilitates the dental procedure. The application of a topical vasoconstrictive nasal spray during the preoperative period reduces or prevents bleeding during the insertion of the nasotracheal tube. • Throat packs may be placed to prevent blood from entering the stomach and causing nausea and vomiting; monitoring their removal is essential to preventing respiratory obstruction after extubation. 33 Sinus and nasal procedures • Nasal and sinus procedures for drainage of chronic sinusitis, polyp removal, repair of a deviated septum, or closed reduction of fractures generally involves the young and healthy patient population. • Nasal polyp removal, for example, may be necessitated by Samter syndrome. A patient with Samter triad has nasal polyps, asthma, and an aspirin allergy. • Nasal surgery may be successfully accomplished with local anesthesia, local combined with IV sedation, or general anesthesia. • Suctioning of the stomach prior to extubation is desirable and may attenuate postoperative retching and vomiting. 34 Trauma • Initial management of the airway depends on the situation at hand. In the case of severe facial or neck trauma, alternative methods of tracheal intubation (e.g., fiberoptic laryngoscopy, retrograde wire placement, jet ventilation via cricothyrotomy, or emergent tracheostomy) may be necessary to secure the airway. • Possible mechanisms by which the upper or lower airway may become obstructed include edema, bleeding from the oral mucosa and palate, intraoral fracture sites, distortion of the nasal passages, injury of the pharynx and sinuses, open lacerations, and the presence of foreign bodies such as avulsed teeth, blood clots, or bony fragments • Injuries of the head and neck may include cervical spine or cranial injury. The seventh cervical vertebra is the most common site of traumatic fracture of the spine. • The use of manual axial inline stabilization and/or a rigid cervical collar in place is recommended. 35 Maxillofacial Trauma and Orthognathic Surgery • The three types of Le Fort fractures, which describe a pattern of fractures involving multiple facial bones are divided into Le Fort I, II, and III. • The Le Fort I fracture is a horizontal fracture of the maxilla extending from the floor of the nose and hard palate, through the nasal septum, and through the pterygoid plates posteriorly. The palate, maxillary alveolar bone, lower pterygoid plate, and part of the palatine bone are all mobilized. • The Le Fort II fracture is a triangular fracture running from the bridge of the nose, through the medial and inferior wall of the orbit, beneath the zygoma, and through the lateral wall of the maxilla and the pterygoid plates. • The Le Fort III fracture totally separates the midfacial skeleton from the cranial base, traversing the root of the nose, the ethmoid bone, the eye orbits, and the sphenopalatine fossa. 36 37 Maxillofacial Trauma and Orthognathic Surgery • A Le Fort I fracture generally causes little difficulty for the anesthesia provider. Patients may be intubated orally or nasally, and the airway secured without a problem. • The Le Fort II and III fractures are of particular concern when contemplating nasal intubation. In both these fractures, disruption of the cribriform plate may occur, opening the underside of the cranial cavity. • The presence of cerebral fluid in the nose, blood behind a tympanic membrane, periorbital edema, or “raccoon-eyes” hematoma are indications that attempts to pass an ETT or nasogastric tube through the nares could lead to inadvertent intracranial placement. 38 Radical neck dissection • Radical neck dissection is required when cancerous tumors have invaded the musculature and other structures of the head and neck. • Determining the appropriate techniques for airway management entails consultation with the surgeon as to the nature, extent, and location of the tumor; therapy administered (radiation or chemotherapy); CT results; history and physical examination; and relevant preoperative laboratory values. • Maintenance of anesthesia is often performed with an inhalation agent and supplemental narcotics. The use of a nondepolarizing muscle relaxant must be discussed with the surgical team preoperatively because a nerve stimulator is frequently used. • The head-up position and open neck veins during surgery may lead to venous air embolism. • Postoperative considerations consist of tracheostomy care, controlled ventilation, chest radiography (to rule out pneumothorax, hemothorax, pulmonary edema), and monitoring for laryngeal edema induced by thrombosis. • https://youtu.be/WQfXc4FprfA?si=HnZIsu4ZfEx6Z3_X 39 40 Conclusion Administering anesthesia for ENT and maxillofacial procedures requires knowledge in both basic and advanced anesthesia techniques. The usual tenets of safe practice must often be adhered to while remaining at a distance from the airway. Good preparation remains imperative. Cooperation and communication between the surgeon and anesthesia provider will improve the quality of care for patients having ENT surgery. 41 References Nagelhout JJ, Elisha S, Heiner JS, eds. (2020). Nurse anesthesia (7th ed.). Philadelphia: Elsevier. Apex Anesthesia Review (2023) 42