Anesthesia for Ear, Nose, Throat, and Maxillofacial Surgery Part 2 PDF

Anesthesia for Ear, Nose, Throat, and Maxillofacial Surgery Part II PREPARATION AND CONSIDERATIONS FOR EAR, NOSE, AND THROAT PROCEDURES Prof. Albert J. Albors DNP, APRN, CRNA University of Puerto Rico Medical Sciences Campus Nurse Anesthesiology Program 1 Objectives • Describe the pertinent anat...

Anesthesia for Ear, Nose, Throat, and Maxillofacial Surgery Part II PREPARATION AND CONSIDERATIONS FOR EAR, NOSE, AND THROAT PROCEDURES Prof. Albert J. Albors DNP, APRN, CRNA 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. • Discusses principles of anesthesia for ENT. 2 Introduction Operative procedures involving the airway, mouth, or bony structures of the face involve a true sharing of the airway between the surgeon and the anesthetist. Therefore, proper preparation requires planning and communication between the surgeon, surgical personnel, and the anesthetist prior to the surgical procedure. Sharing the airway also requires preparing and planning the use of the appropriate equipment. 3 Obtaining a thorough history and performing an extensive evaluation of the airway for the ENT patient is crucial. A good examination of the airway will: History and airway evaluation I. allow for a careful and deliberate approach to airway management. II. aid in evaluating the need for additional equipment and assistance. III. include alternative approaches for the difficult airway if the initial plan proves not to be successful. In ENT surgery the head of the table is often rotated 90 to 180 degrees away from the anesthetist, resulting in a vulnerable airway to which the anesthetist may have little or no access. 4 Shared airway considerations Signs of air leak around tube • Bubbling • Sound of air escaping • Smell of anesthetic agent Occlusion • CO2 waveform • Inspiratory pressures • Chest wall motion • Good auscultation 5 Position for surgery 6 Preparation for surgery • The anesthesia circuit and other monitors should be temporarily and briefly disconnected before the bed is turned. This will prevent undue tension on the circuit and other lines that could lead to traumatic extubation or loss of access. • Ventilation of the patient with 100% oxygen and adequate tidal volumes for 3 to 5 minutes before disconnection will denitrogenate the functional residual volume and provide an extra reservoir of oxygen during the turn, preventing even a short period of hypoxia. • However, if a volatile agent is the primary source of anesthesia, the addition of IV anesthesia during this preoxygenation is necessary to maintain an adequate level of anesthesia and/or amnesia during this period. A saturation of 100% is a reasonable goal before the disconnection and table movement. 7 Specialized equipment in ENT surgery • Standard ETTs equipped with flexible or straight connectors are appropriate for many ENT procedures. The diameter and length of the ETT will affect ventilation and seal of the airway. • A variety of designs are used to limit encroachment of the ETT into the surgical field, prevent kinking of the ETT when severe angles are necessary, prevent fires in the airway during laser therapy, and provide maximal patient ventilation and safety. • Several ETTs have been introduced for use in ENT anesthesia. The purpose for the evolution of these various types of ETT cuffs was to reduce cuff pressure on the tracheal wall allowing for improved tracheal perfusion, mitigate tracheal injury, and optimize airway access. 8 Oral RAE tubes Oral RAE tubes (named after inventors Ring, Adair, and Elwyn) are an excellent choice for cleft palate repair, tonsillectomy, uvulopalatopharyngoplasty, and procedures of the eye or upper face. 9 Nasal RAE tubes Nasal RAE tubes are particularly well suited to maxillofacial surgery that does not allow for oral intubation. The nasal RAE can be used for cosmetic procedures of the face, surgical procedures of the oral cavity and mandible, or to correct malocclusion. 10 Armored or reinforced ETTs • Armored or reinforced ETTs all have an embedded coiled wire or plastic coil strand to produce a tube with greater flexibility and memory. • Armored tubes for oral or nasal intubation resist kinking and retain their original integrity. • They are useful when acute neck flexion or severe angles of the ETT are required, as in procedures involving the base of the skull or posterior aspect of the neck. 11 Armored or reinforced ETTs 12 Metal-impregnated tubes Several varieties of metal-impregnated tubes are available for use with laser surgery; these are designed to reduce the occurrence of an airway fire. The cuff of the laser tube is usually filled with saline to dampen or prevent ignition. In addition, it is recommended that the cuff be filled with methylene blue-dyed saline so that a cuff perforation is easily detected. 13 Intubating LMA Although not classified as an ETT, the laryngeal mask airway (LMA) and the intubating LMA may be used to facilitate intubations, as well as control the airway. The LMA does not produce tracheal stimulation, which can be a considerable advantage in ENT procedures. https://youtu.be/P4gHL3cKXmc 14 Pharmacologic Considerations The use of local anesthetics is particularly prevalent during nasal and sinus surgery. The most used local anesthetics for ENT surgery include the amide-based drugs. Though many procedures are performed using topical and local anesthesia as the sole agent, this may also occur in combination with IV sedation, monitored anesthesia care, or general anesthesia. 15 Topical Anesthetic Drugs 16 Vasoactive Drugs • The duration of action of a local anesthetic is proportional to the time the drug is in contact with nerve fibers. For this reason, epinephrine in varying concentrations (1:200,000 or 5 mcg/mL; 1:100,000 or 10 mcg/mL; and 1:50,000 or 20 mcg/mL) may be added to local anesthetic solutions to produce vasoconstriction. • Vasoconstriction limits systemic absorption and maintains a higher drug concentration in the vicinity of the nerve fibers to be anesthetized, thus extending the effects of the local anesthetic. Addition of epinephrine to a local anesthetic prolongs the duration of blockade and decreases systemic absorption and plasma concentrations, thus decreasing toxicity. 17 Anticholinergics • The antisialagogue effects are useful in certain intraoral procedures that require a drier operative field. • Glycopyrrolate may be a better choice than atropine because it produces less tachycardia in comparison to atropine. • Glycopyrrolate also does not readily cross the blood-brain barrier and thus lacks sedative effects. 18 Corticosteroids • Glucocorticoids may be administered preoperatively and intraoperatively to decrease laryngeal edema formation, reduce nausea and vomiting, and prolong the analgesic effects of local anesthetics. • Dexamethasone was also reported to prolong the analgesic effects of local anesthetics. • Although the use of steroids may be beneficial, they can also create sufficient immunosuppression to mask inflammation or infection. 19 Postoperative Nausea and Vomiting • ENT procedures, particularly of the middle ear, are associated with a high incidence of PONV. • The accumulation of blood in the posterior oropharynx, which may drain into the stomach or be swallowed during the postoperative period, can lead to PONV. • Care must be taken that the patient is awake, all surgical packs are removed, and suctioning of the airway precedes the extubation process, producing a clear airway and ensuring the control of protective airway reflexes. 20 Deliberate Controlled Hypotension • The surgeon may request deliberate controlled hypotension to reduce blood loss. Patients must be individually evaluated prior to controlled hypotension to determine a safe mean pressure. • Extensive dissection is required for many head and neck tumors with operative times extending to 12 or more hours. Considerable fluid replacement, blood loss, electrolyte imbalances, and cardiovascular and respiratory changes may occur during surgery. • Although the research is conflicting as to what values are best practice, the author’s practice is to not allow the mean pressure to fall below 50 to 60 mm Hg or a greater than 20% decrease of baseline MAP. • Regardless of the technique or medication chosen, it is imperative that urine output, mean arterial blood pressure, cerebral and cardiac perfusion pressure, and arterial blood gases be closely monitored and maintained. 21 22 Select techniques for ENT surgery • Laser technology is discussed in detail in chapter 47 from Nagelhout. Some specific issues concerning lasers are relevant to ENT surgery. The two most common lasers used in ENT surgery are the CO2 (10,600nm) and Nd:YAG (1,064nm). • The wavelength of the Nd:YAG laser beam is shorter as it passes through the garnet than that of the CO2 laser. The shorter wavelength allows less absorption by water and therefore less tissue penetration. • The CO2 laser produces a beam with a relatively long wavelength that is absorbed almost entirely by the surface of these tissues, vaporizing cellular water. • For example, the shorter wavelength of the Nd:YAG allows the laser light to pass through the cornea, whereas the longer wavelength of the CO2 laser would burn the cornea. 23 Laser safety • Specific concerns include eye protection with appropriate colored glasses, avoidance of the dispersion of noxious fumes, and fire prevention. • Stray or reflected beams of the Nd:YAG laser can traverse the eye to the retina; therefore green-lensed eye protection for all personnel is mandatory during use of the Nd:YAG laser. • The required protective eyewear for CO2 lasers can be any clear glass or plastic that surrounds the face. • Orange-red eye protection is required for the potassium titanylphosphate (KTP) laser, and orange glasses are required for the argon laser. 24 25 26 27 Endoscopy • Endoscopic surgery includes panendoscopy, laryngoscopy, microlaryngoscopy (laryngoscopy aided by an operating microscope), esophagoscopy, and bronchoscopy. All these procedures can be performed using a rigid or flexible endoscope. • One of the most common endoscopic procedures performed is endoscopic sinus surgery. • Endoscopic sinus surgery is often associated with recurrent and seasonal allergies leading to polyps. Patients undergoing endoscopic surgery are often also being evaluated for pathology responsible for hoarseness, stridor, or hemoptysis. • Other possible reasons for endoscopic examination include foreign-body aspiration, papillomas, trauma, tracheal stenosis, obstructing tumors, or vocal cord dysfunction. 28 Endoscopy • Several complication can arise with endoscopic surgery: eye trauma, epistaxis, laryngospasm, and bronchospasm; excessive plasma levels of local anesthesia and epinephrine have also been reported. • Premedication with an antisialagogue to dry secretions and a full regimen of acid aspiration prophylaxis in aspiration-prone patients may be indicated. An awake oral or nasal intubation with minimal sedation and topical anesthesia of the oral cavity, pharynx, larynx, and nasopharynx is common. • Emergence should include adequate oropharyngeal suctioning, humidified oxygenation, and observation in the PACU for laryngeal spasm, or post extubation croup or stridor. 29 Jet Ventilation • Jet ventilation has been used extensively for laryngeal surgery. When the trachea is not intubated, a metal needle mounted in the operating laryngoscope or passed through the cords can be used for jet ventilation. • Jet ventilation may be performed manually, using a simple hand valve attached to an appropriate oxygen source, or together with various mechanical devices that allow for adjustment of rate and oxygen concentration. Because oxygen can support combustion, the lowest concentration of oxygen possible should be used. • There is no absolute contraindication to high-frequency jet ventilation (HFJV); however, it can be difficult maintaining oxygenation and/or CO2 elimination in certain patients. These include patients who are morbidly obese, have a stiff thorax, or advanced forms of restrictive and/or obstructive lung disease, lung fibrosis, and reduced alveolar-capillary diffusion capacity, such as with pulmonary edema. Jet ventilation should be avoided in any situation in which an unprotected airway is a concern (e.g., full stomach, hiatal hernia, or trauma). 30 Jet Ventilation • Common types of HFJV include supraglottic, infraglottic, transtracheal, and via a rigid bronchoscope. • HFJV is ventilation at low tidal volumes with high respiratory rates. A needle connected to a high-pressure hose with a regulator to adjust rate and volume is used to deliver the ventilation. With the tip of the needle either above or below the glottis, the anesthetist directs a high-velocity jet stream of oxygen into the airway lumen. • The lungs are ventilated as the mixture of oxygen forces air into the lumen. Introduction of high-pressure (up to 60 psi) jet-injected oxygen entrains room air into the lung, allowing the jet stream of gases into the airway for ventilation. • IV anesthetic techniques are used with HFJV because environmental contamination by leaking volatile agents is a concern. 31 https://youtu.be/Ia0KC61pAVc?si=8JKnDcx-fxvKTvga 32 Foreign-Body Aspiration • Aspiration of foreign bodies is a common problem that carries high morbidity and mortality, particularly in children. • A common site of foreign-body aspiration is the right bronchus. If the patient is supine when the aspiration occurs, the object will most likely be found in the right upper lobe. • Signs of aspiration include wheezing, choking, coughing, tachycardia, aphonia, and cyanosis. These signs indicate an obstructive, severe irritation and swelling in the airway. • Although rigid bronchoscopy has been the traditional diagnostic gold standard, the use of CT, virtual bronchoscopy, and flexible bronchoscopy is increasing. 33 Foreign-Body Aspiration • Anesthetic management depends on the location of the airway obstruction, the size and location of the object, and the severity of the obstruction. If the foreign body is located at the level of the larynx, a simple laryngoscopy with Magill forceps should allow for easy removal of the object. Care must be taken not to dislodge the object and allow it to fall deeper into the airway. • If the foreign body is in the distal larynx or trachea, the patient should have an inhalation induction performed in the operating room, maintaining spontaneous respiration. With the patient spontaneously breathing, the surgeon will most likely use a rigid bronchoscope for extraction of the foreign body. • An antisialagogue, H2 antagonist, and metoclopramide are often administered intravenously to decrease secretions and promote gastric emptying; the secretions may obscure the view through the bronchoscope. 34 Foreign-Body Aspiration • Laryngeal and subglottic edema may occur for 24 hours after removal of a foreign body. • To check for airway edema, the cuff of the ETT can be deflated, if not contraindicated, and the lumen of the ETT should be occluded for one or two breaths during inspiration and expiration while listening for air movement around the tube. • If there is no air escaping around the ETT, postoperative sedation and ventilation might be considered. • Please watch the following video for reference https://youtu.be/3Oxe2Q6DZ_Y?si=OsrxEFKYIIbNQre9 35 References Nagelhout JJ, Elisha S, Heiner JS, eds. (2020). Nurse anesthesia (7th ed.). Philadelphia: Elsevier. Apex Anesthesia Review (2023) 36