Anesthesia for laryngeal surgery

INTRODUCTION — A variety of laryngeal procedures may be performed to improve respiratory function or phonation, or to resect diseased tissue. Anesthetic concerns specific to these procedures include potential difficulty with airway management, sharing the airway with the surgeon, the effects of preoperative treatment for laryngeal pathology (particularly radiation for cancer), and the patient comorbidities that predispose to laryngeal disease. Laryngeal surgery requires especially close coordination with the surgeon, whether the procedure is minor or more complex.

This topic will discuss general principles of anesthetic management for laryngeal procedures, and management for some common procedures.

Anesthesia management for head and neck surgery in general is discussed separately. (See "Anesthesia for head and neck surgery".)

Anesthesia for tracheal surgery, management of the difficult airway, and airway management for patients with laryngeal trauma are also discussed separately.

●(See "Management of the difficult airway for general anesthesia in adults".)

●(See "Anesthesia for adult trauma patients", section on 'Airway management'.)

LARYNGEAL ANATOMY — The larynx is comprised of a cartilaginous skeleton, muscles (extrinsic and intrinsic), and a mucosal lining. The main functions of the larynx involve phonation, maintenance or airway patency and protection, and generation of Valsalva. The anatomy of the larynx, including the cartilages, vocal folds (cords), muscles, and nerve supply are discussed in detail separately (figure 1 and figure 2). (See "Hoarseness in adults", section on 'Laryngeal anatomy and physiology'.)

Anatomic changes related to cancer of the larynx or nearby structures, or to cancer treatment, can increase complexity and difficulty with airway management. The fat filled spaces anterior and posterior to the epiglottis and lateral to the vocal folds, if involved with tumor, can decrease tissue compliance, narrow the airway, change the axial alignment of intubation path, and increase difficulty with passage of an endotracheal tube (ETT). In addition, radiation damage, inflammation, or mass effect on lymphatic or venous drainage can cause laryngeal edema, resulting in tissue friability and airway narrowing. Lymphatic drainage of the larynx is discussed separately. (See "Treatment of early (stage I and II) head and neck cancer: The larynx".)

PREANESTHETIC ASSESSMENT — A medical history and anesthesia-directed physical examination should be performed for all patients who undergo anesthesia. (See "Preoperative evaluation for anesthesia for noncardiac surgery" and "Anesthesia for head and neck surgery", section on 'Assessment of comorbidities'.)

For patients who undergo laryngeal surgery, we focus the preanesthesia evaluation on the airway, and on those medical conditions that are associated with complications during and after these procedures.

Airway assessment and planning — All patients should have a preanesthesia airway assessment, with the goal of identifying possible difficulty with airway management and risk factors for aspiration during anesthesia. (See "Airway management for induction of general anesthesia", section on 'Airway assessment'.)

Difficulty with airway management is more common for patients who undergo head and neck procedures, particularly for cancer, than for many other surgical patients. (See "Anesthesia for head and neck surgery", section on 'Incidence of airway difficulty'.)

Difficulty with airway management in patients with laryngeal cancer varies, and may depend on the stage and the location of the cancer. Early laryngeal cancer (eg, carcinoma in situ, stages T1 and T2) primarily consists of soft tissue pathology, and passing an endotracheal tube (ETT) through the tumor site is usually not difficult. As an example, early glottic cancer may impair vocal fold mobility, but the vocal fold is not usually fixed or obstructive [1]. However, in more advanced cancer with damage of the underlying cartilage, the airway lumen may be narrowed and tissue compliance may be decreased, such that passing an ETT can be difficult or impossible. Thus, in patients with advanced cancer, the plan for airway management should be discussed with the surgeon, including the appropriate size of an ETT and the possibility of awake intubation or tracheostomy. (See 'Surgical considerations and team planning' below.)

The 2022 Practice Guidelines for Management of the Difficult Airway from the American Society of Anesthesiologists lists 15 items that can be used to predict airway difficulty, including facial features, anatomical metrics, and ratios (table 1) [2]. Some commonly assessed features and non-reassuring findings are shown in a table (table 2). These fundamental tools are essential for routine use, but are insufficient for patients who undergo laryngeal procedures. Many patients will also undergo awake transnasal flexible laryngoscopy as part of preoperative evaluation to assess the view of the glottis, the maximal airway capacity at the disease site, axial alignment of the airway, presence and position of obstructive lesions, condition of the mucosa and edema, and vocal fold motion. For patients with laryngeal cancer, repeat flexible laryngoscopy should be performed on the day of surgery in selected cases, as lesions can progress and change quickly (picture 1).

For patients with laryngeal pathology, airway-related imaging or stroboscopy (which assesses vocal fold motion) may help identify the potential problems with airway management mentioned above, and should be reviewed as part of perioperative airway assessment. Computed tomography (CT) or magnetic resonance imaging (MRI) can identify masses, anatomic distortion, and evidence of tissue edema. However, the limits of radiographic studies for evaluation of the laryngeal airway should be appreciated. A study performed a few weeks prior to surgery may not reflect the airway condition at the time of the procedure for rapidly progressing disease. In addition, CT cannot be used to evaluate vocal fold mobility unless multiple images are acquired at various stages of the respiratory cycle, and CT studies do not reliably estimate the maximal lumen of the airway. Virtual endoscopy [3,4], airway ultrasound, and cone beam CT [5] are emerging technologies for airway evaluation whose clinical applications have not been established.

Comorbidities — Laryngeal cancers and some benign laryngeal conditions (eg, vocal fold polyps, Reinke's edema) (picture 2) are associated with tobacco and/or alcohol use, which predispose patients to cardiopulmonary, liver, and other comorbidities that may affect anesthetic management. (See "Epidemiology and risk factors for head and neck cancer", section on 'Risk factors' and "Anesthesia for head and neck surgery", section on 'Assessment of comorbidities'.)

Prior radiation therapy — Radiation therapy (RT) is commonly used as the primary therapy for laryngeal cancer. Many patients undergoing cancer surgery have been previously treated with RT, which can cause acute and long-term consequences, including laryngeal edema (picture 3 and image 1) and/or tissue fibrosis, any of which can result in difficulty with airway management. Important issues related to prior RT include the following:

●Patients who have received RT may be volume depleted, malnourished, and anemic, and are at risk for profound hypotension during induction of anesthesia.

●Mumbling or difficulty swallowing are often signs of laryngeal edema or significant mucositis in upper aerodigestive tract, and may predict difficulty with airway management.

●Radiation-induced skin reactions (eg, facial and neck erythema or edema), although possibly concomitant with upper aerodigestive tract edema, are not reliable predictors of laryngeal edema; patients with skin changes may not have coexisting laryngeal edema, and vice versa.

●Postradiation tissue fibrosis involves tissue atrophy and contractures (such as trismus), and cannot be relaxed with neuromuscular blocking agents (NMBAs).

●Neck RT can also cause acute or chronic baroreflex dysfunction (or rarely, baroreflex failure), which is more common in patients with bilateral neck radiation and those who have completed a full course of treatment [6,7]. While most patients with impaired baroreflexes remain asymptomatic during routine activity [8,9], they may exhibit labile blood pressure and heart rate during anesthesia [10,11]. The incidence of baroreflex dysfunction after RT is unknown. Although routine preoperative screening for impaired baroreflex sensitivity is impractical and unnecessary, repeat episodes of orthostatic hypotension in a patient who have undergone neck RT may suggest baroreflex dysfunction and should raise the concern for possible hemodynamic instability during the perioperative period.

SURGICAL CONSIDERATIONS AND TEAM PLANNING — The surgeon and the anesthesiologist share the airway during laryngeal surgery. Thus the plan for anesthesia management requires close coordination with the surgeon, particularly with respect to airway management. The following issues should be considered preoperatively, and are discussed in more detail separately (see "Anesthesia for head and neck surgery", section on 'Surgical considerations'):

●Selection of airway management device

●Intubation technique and backup plans

●Ventilation strategy (eg, spontaneous ventilation, standard mechanical ventilation, jet ventilation [JV], apneic ventilation)

●Need for neuromuscular blockade

●Fire risk

●Orientation of the operating table during the procedure (turning, or 90 versus 180 degrees away from anesthesia machine), and arm positioning including tucking one or both arms

ENDOSCOPIC TRANSORAL LARYNGEAL SURGERY

Choice of anesthetic technique — Many endolaryngeal procedures are performed under general anesthesia, and therefore require airway management and ventilation. Surgery for some benign laryngeal lesions must or can be performed under local anesthesia, with or without sedation. (See 'Common laryngeal procedures' below.)

Intravenous induction of anesthesia is usually performed in adults, unless inhalation induction is indicated based on patient factors. (See "Induction of general anesthesia: Overview".)

If endotracheal intubation is performed, either inhalation or intravenous anesthetics can be used for maintenance of anesthesia, with drugs and doses based on patient factors, and practice varies (see "Anesthesia for head and neck surgery", section on 'Choice of anesthetic agents'). If a tubeless method of airway management is chosen, intravenous anesthetics must be used to maintain stable levels of anesthesia and to avoid pollution of the operating room with anesthetic gases. (See 'Tubeless ventilation techniques' below.)

Airway management and ventilation — Airway management and ventilation for head and neck procedures in general are discussed separately (see "Anesthesia for head and neck surgery", section on 'Airway management strategy'). Issues specific to laryngeal surgery are discussed here.

Supraglottic airways — Supraglottic airways (SGAs) are rarely used for laryngeal procedures, though they may be used for flexible scope assisted procedures (eg, laryngeal or subglottic biopsy).

Endotracheal intubation — Endotracheal intubation is performed for many laryngeal procedures; a cuffed endotracheal tube (ETT) secures the airway, facilitates mechanical ventilation, prevents leakage of anesthetic gases or oxygen from the trachea into the airway, and prevents soiling of the lungs with blood or debris. However, the ETT may interfere with visualization and dissection of the laryngeal lesion. During intubation it is important to avoid traumatizing laryngeal lesions.

After intubation, the ETT should be positioned according to the surgeon's preference to facilitate introduction of surgical instruments. It must be securely taped to the lower jaw or the corner of the mouth to avoid outward displacement of the ETT when the mouth is opened and the neck is extended for laryngeal suspension. This is particularly important because immediate access to the airway will be difficult or impossible once the head of the operating table is turned 90 or 180 degrees away from the anesthesiologist. The anesthesia breathing circuit should be configured to allow unrestricted surgical access.

Choice of endotracheal tube — In general, the smallest ETT capable of supporting appropriate ventilation is used. In most cases, a 5 or 5.5 mm inner diameter (ID) microlaryngeal tube is adequate to meet respiratory and surgical needs. However, the cuff of 5 or 5.5 mm ID tube may not adequately seal the adult tracheal lumen without overinflating the cuff. Thus, cuff pressure should be checked after a seal is achieved with one of these small ETTs, and if necessary, the tube should be replaced with a slightly larger one.

Laser-resistant endotracheal tubes — Laser-resistant ETTs are used for laryngeal laser surgery to reduce the risk of airway fire. The selection of the laser-resistant ETT should be based on the type of laser used for the procedure. Laser-resistant tubes vary with respect to their materials, the portions of the tube that are laser resistant, the relative size, and the type of laser for which they may be used. Laser-resistant ETTs have larger external diameters for a given internal diameter because of the laser resistant coating or materials.

Most laryngeal surgery is performed with carbon dioxide (CO₂) lasers. A commonly used laser-resistant ETT, the Laser-Flex cuffed ETT, is CO₂ and KTP laser resistant and has two cuffs (picture 4). The second, distal cuff provides a backup gas seal if the proximal cuff is damaged. The proximal ETT cuff should be placed well below the vocal folds to minimize the chance of damage, while taking care to avoid endobronchial intubation, and both cuffs should be inflated. The cuff position should be rechecked after the patient is positioned for surgery, since neck extension can move the tube closer to the vocal folds. As a practical matter, there are no depth markings on the Laser-Flex ETT, so the ETT position is difficult to assess. The author marks the tube at 23 cm from the tip prior to use. The tube is then passed through the vocal cords and advance to the point at which the 23 cm mark is at the teeth, and withdrawn as necessary to achieve bilateral breath sounds. After the suspension laryngoscope is in place, the cuff position below the glottis opening is confirmed visually.

The American Society of Anesthesiologists Practice Advisory for the Prevention and Management of Operating Room Fires recommends that the ETT cuff should be filled with saline tinted with methylene blue, to alert the clinician to an ETT cuff rupture during airway laser surgery [12]. Further, the surgeon should alert the anesthesiologist several minutes before the laser will be activated; the fraction of inspired oxygen (FiO₂) should be reduced to <30 percent, and nitrous oxide should be discontinued since it can leak around the ETT cuff, after which several minutes should be allowed to pass if a higher concentration of oxygen had been in use [13]. Prevention and management of airway fire is discussed further separately. (See "Fire safety in the operating room", section on 'Special precautions during airway surgery'.)

Tubeless ventilation techniques — The "tubeless" ventilation techniques, including supraglottic or subglottic jet ventilation (JV) and apneic oxygenation (eg, high flow nasal oxygen [HFNO]), may be used for microlaryngeal surgery for various procedures (eg, phonosurgery, resection of laryngeal pathology, removal of a laryngeal foreign body), generally for short or simple procedures. The need for tubeless ventilation is primarily the surgeon's decision. General considerations include the following:

●Total intravenous anesthesia is required if JV or HFNO is used, since ventilation is performed without the use of the anesthesia machine and the ability to deliver anesthetic gases (picture 5).

●Tubeless techniques may not provide adequate oxygenation in obese patients, or during prolonged procedures. The limits of a tubeless technique should be discussed with the surgeon preoperatively, and a backup plan should be formulated.

●High FiO₂ is used to reduce oxygen desaturation during tubeless techniques, so airway fire risk is high and must be addressed. (See "Fire safety in the operating room", section on 'Risk prevention: High-risk procedures'.)

●Low-flow apneic oxygenation technique may also be used in selected cases, such as the patients with a low body weight. In a single institution observational study of 64 adults who underwent microlaryngeal surgery with oxygen provided at 0.5 to 1 L/minute via a 10 French catheter tracheal catheter placed through the glottis, all but two cases were completed using low-flow oxygen without oxygen desaturation, with a mean duration of surgery of 18.7 minutes [14]. In two patients the technique was abandoned due to desaturation to ≤92 percent. Compared with a high-flow technique, the advantages of low flow are that it provides a quiet field and reduces field contamination from surgical debris.

●Tubeless techniques should be considered carefully, along with the surgeon, for patients with predicted difficulty with endotracheal intubation, since intubation may be required quickly if adverse airway events occur during surgery, such as aspiration or the inability to oxygenate or ventilate with JV.

Spontaneous ventilation — Spontaneous ventilation may be used in certain phonosurgery procedures such as thyroplasty. If intraoperative stroboscopy is planned, the patient must be conscious and able to cooperate.

Apneic intermittent ventilation — With this technique, ETT is intermittently removed and replaced by the surgeon through the lumen of the operating laryngoscope, to allow surgery on still and unobstructed airway structures.

Jet ventilation — Both low- and high-frequency JV can be used for laryngeal surgery. JV provides a relatively quiet surgical field, with minimal laryngeal motion, without the need to interrupt ventilation. Laryngeal tissue vibration is a concern with supraglottic JV, whereas barotrauma is a concern with subglottic JV. Supraglottic JV via a jet compatible laryngoscope is a commonly used technique. JV is discussed separately. (See "Anesthesia for head and neck surgery", section on 'Jet ventilation' and "Anesthesia for adult bronchoscopy", section on 'Jet ventilation'.)

High flow nasal oxygen — Transnasal humidified high flow nasal oxygen (HFNO) is another technique that allows apneic oxygenation without an airway device in place. For laryngologic surgery, HFNO is typically used for preoxygenation at a flow rate of 30 L/minute. After induction of anesthesia, HFNO is temporarily stopped to confirm the ability to ventilate by face mask, then restarted at 70 L/minute. Airway patency must be meticulously maintained until the surgical laryngoscope is inserted. Since capnography is not possible when using HFNO, transcutaneous carbon dioxide monitoring should be used where available during laryngologic surgery.

Examples of studies of the use of HFNO for airway management during general anesthesia include the following:

●In a landmark study, 25 patients who had general anesthesia were preoxygenated with a high-flow nasal oxygen (HFNO) system at 70 L/min, which was continued for apneic oxygenation [15]. The patients underwent a variety of surgical procedures, including laryngologic surgery, which required different methods for definitive airway management. No patient desaturated to <90 percent peripheral arterial oxygen saturation (SpO₂), during apneic periods lasting 5 to 65 minutes. The rate of risk of end-tidal CO₂ (EtCO₂) was 1.13 mmHg (or 0.15 kPa) per minute, lower than reported rates of 3 to 4.2 mmHg/minute with classic apneic oxygenation [16-18].

●In an observational study of 30 patients who underwent laryngologic surgery using HFNO at 70 L/minute for up to 30 minutes of apnea, no patient had an SpO₂ <91 percent [19]. PaCO₂ rose at 1.8 mmHg/minute. In one patient, JV was started when the partial pressure of arterial carbon dioxide (PaCO₂) reached 82.5 mmHg.

Experience with HFNO for laryngeal surgery is limited and requires further study. The author usually uses it as part of a combined technique, along with JV backup if necessary. With this technique, the author sets up a JV handle with the pressure regulated at 30 psi, with a 5.5 or 6 mm ID microlaryngeal tube. The surgeon uses a JV compatible laryngoscope. HFNO is used for oxygenation while the surgeon engages and adjusts the laryngoscope, and is continued during surgery as long as the patient remains well oxygenated. If oxygen desaturation occurs, JV is initiated, and if necessary, endotracheal intubation is performed.

HFNO is discussed in more detail separately. (See "Preoxygenation and apneic oxygenation for airway management for anesthesia".)

Surgical exposure (suspension laryngoscopy) — After induction of anesthesia the surgeon may examine the airway using direct laryngoscopy and if necessary, proceed to suspension laryngoscopy. Suspension laryngoscopy frees the surgeon to use two hands for the procedure. The laryngoscope is held in place with a mechanism that either rests on the patient’s chest (fulcrum based suspension) (picture 6), or is attached to the frame of the operating table (gallows type suspension).

The surgeon can choose from a wide variety of laryngoscope blades depending on the procedure. Examples of laryngoscopes used for laryngeal procedures are shown in a figure (picture 7). The use of a video monitor connected to either a camera inserted in the laryngoscope or a microscope can allow the anesthesiologist to monitor the airway and the progress of the procedure.

Intense surgical stimulation — Endolaryngeal surgery does not typically cause more than mild postoperative pain, but is associated with intense intraoperative stimulation, from the surgical retractor and from laryngeal manipulation. Laryngoscopy and placement or adjustment of the surgical retractor causes abrupt pressure on airway structures (primarily the base of the tongue and hypopharynx) which is intensely stimulating [20-22], and often requires rapid adjustment of anesthetic depth and/or administration of rapid-acting vasoactive agents (eg, esmolol, nicardipine). Rarely, severe bradycardia or sinus pause may occur in response to either placement of the retractor, or the start of laryngeal resection [11]. Releasing the retractor and administration of ephedrine (10 mg IV) often quickly restores adequate hemodynamics; for cardiac arrest, cardiac compressions and advanced cardiac life support may be required.

Patients with prior neck radiation may be at increased risk of transient sinus pause due to baroreflex dysfunction (see 'Prior radiation therapy' above) We administer prophylactic glycopyrrolate (0.2 to 0.4 mg IV) prior to retractor placement in patients with baseline bradycardia (ie, heart rate 40 to 50 beats per minute).

Need for neuromuscular blockade — Neuromuscular blockage is usually monitored with a twitch monitor at the adductor pollicis muscle (APM). However, the laryngeal muscles recover from neuromuscular block faster than the APM (see "Monitoring neuromuscular blockade", section on 'Differential muscle sensitivity'). The need for neuromuscular blockade should be discussed with the surgeon preoperatively. Profound muscle paralysis is essential during microlaryngeal resection [23]. Thus the author maintains deep neuromuscular blockade (ie, zero twitches using train-of-four stimulation with a peripheral nerve stimulator). (See "Monitoring neuromuscular blockade", section on 'Train-of-four'.)

Smooth emergence and extubation — Emergence from anesthesia after laryngeal surgery should include a smooth, rapid awakening and extubation, devoid of coughing, bucking, and straining. Ongoing communication with the surgeon regarding progress and timing of completion of the procedure is important for preparing for anesthetic emergence. The author usually allows recovery of spontaneous ventilation prior to starting emergence, and prefers to extubate when awake and following commands. Planning for extubation and techniques for a smooth extubation are discussed separately. (See "Anesthesia for head and neck surgery", section on 'Emergence from anesthesia' and "Extubation following anesthesia", section on 'Management of extubation'.)

Postoperative care — Patients who undergo laryngeal procedures should be monitored closely for stridor, wheezing, and signs of respiratory obstruction. Postoperative airway obstruction is rare, and most microlaryngeal surgery can be performed on an outpatient basis. Mild post-extubation inspiratory strider may occur as a result of residual anesthesia or opioids; continuous positive airway pressure (CPAP) support often resolves stridor while the patient fully awakens.

Patients with postoperative obstructive local edema or hemorrhage require emergency airway management in the operating room with the surgeon present. Flexible scope intubation is an option for management of a stable airway, whereas tracheostomy may be required for emergency management. (See "Overview of the management of postoperative pulmonary complications".)

COMMON LARYNGEAL PROCEDURES — General principles for anesthetic management are discussed above. Anesthetic considerations for specific common procedures are discussed here.

Phonosurgery — Phonosurgery refers to the procedures performed primarily to treat voice disorders. A variety of conditions can cause hoarseness and changes in voice quality. (See "Hoarseness in adults", section on 'Benign vocal fold lesions'.)

Procedures that do not require microsurgery can often be performed with regional and/or topical anesthesia administered by the surgeon, with or without sedation [24]. The procedure may require that the patient remains conscious during the adjustment of vocal folds in order for the surgeon to assess respiratory function and voice improvement. In some cases, patients may be awakened from general anesthesia during the procedure to test voice function.

Procedures that require direct or suspension microlaryngoscopy, surgical innervation of the larynx, and excision of some soft tissue lesions require general anesthesia.

Laryngoplasty — The terms laryngoplasty and thyroplasty refer to a number of procedures that may be performed to improve either respiratory function (usually to make glottic opening larger) or voice (to make vocal folds closer). The anesthetic technique should be discussed with the surgeon, and may be determined by the need (or lack thereof) for assessment of function during surgery.

Injection laryngoplasty — Injection laryngoplasty is an endoscopic procedure performed for glottic insufficiency and/or voice disorders. A bulking agent (eg, bovine collagen, gelfoam, hyaluronic acid gel) is injected into the larynx to medialize the vocal fold and bring the vocal folds closer. Injection laryngoplasty usually takes 15 to 20 minutes. It can often be performed with local anesthesia with no or minimal sedation. General anesthesia may be required in select cases to immobilize the surgical field for precision injection, or for patients who are highly anxious.

Airway and ventilation management for endolaryngeal procedures under general anesthesia are discussed above. (See 'Airway management and ventilation' above.)

Injection laryngoplasty results in only mild postoperative throat discomfort, and opioids should not be required for analgesia. Therefore, for patients who receive general anesthesia, the author usually administers short-acting agents (eg, esmolol, nicardipine) if necessary to treat intraoperative hypertension or tachycardia, rather than opioids.

For general anesthesia for these brief procedures, the author does not typically perform endotracheal intubation. He uses a succinylcholine infusion for neuromuscular blockade, aiming for no twitches with twitch monitoring, and uses facemask ventilation during anesthetic induction. After induction of anesthesia and onset of neuromuscular block, the surgeon engages the suspension laryngoscope and performs the quick procedure. At the end of surgery, mask ventilation is used to support the airway until spontaneous ventilation is adequate. If surgery lasts longer than expected, jet ventilation (JV) may be used to continue oxygenation and ventilation. Placement of a supraglottic airway (SGA) should be avoided, as the SGA can disrupt the injection site.

Operative laryngoplasty — Operative laryngoplasty or thyroplasty procedures are usually performed with local anesthesia with or without sedation. Phonation is necessary for voice adjustment or for performing stroboscopy during the procedure.

A variety of laryngoplasty or thyroplasty procedures are performed to modify vocal fold function. Medialization laryngoplasty is commonly used to correct unilateral vocal paralysis. During the procedure, a permanent wedge (eg, Montgomery implant) is implanted to medialize the impaired vocal cord through a small incision in the neck.

When anesthesia is required, mild to moderate sedation is usually sufficient. The procedure typically takes 45 to 90 minutes. Pain is minimal and the anxiety level is moderate during the surgery. The procedure and anesthesia goals should be thoroughly discussed with the patient to reduce emotional distress during voice adjustment. For patients who are particularly anxious, moderate sedation can be administered during tissue dissection, lightened during voice testing, and readministered during skin closure. The author usually uses propofol sedation for these procedures. (See "Monitored anesthesia care in adults", section on 'Propofol'.)

Supplemental oxygen (2 to 4 L/min) via nasal cannula may be required if sedation is used. Fire precautions should be followed if electrocautery is used. (See "Fire safety in the operating room", section on 'Risk prevention: High-risk procedures'.)

Postoperative pain is minimal after operative laryngoplasty, and is usually well controlled with nonopioid analgesics. Nonsteroidal anti-inflammatory drugs (NSAIDs) should be administered only after discussion with the surgeon, due to the possibility of postoperative bleeding. Patient should be instructed to abstain from speech. The risk of postoperative airway obstruction is low since breathing and voice are finely adjusted during the procedure. One single institutional study of 147 patients with type I thyroplasty (vocal fold medialization) reported that the overall postoperative complication was 7 percent. Three percent of patients developed postoperative airway compromise, but none of them needed surgical intervention or tracheal intubation [25].

Microlaryngeal surgery — Microlaryngeal surgery is performed for excision of a variety of vocal fold lesions, including scarring, inflammatory tissue, vascular lesions, and early laryngeal cancers (picture 8).

These procedures are performed with specialized laryngoscopes under general anesthesia. Airway and ventilation management are discussed above (see 'Airway management and ventilation' above). The duration of microlaryngeal surgery varies, but rarely lasts beyond two hours.

General anesthesia with endotracheal intubation is preferred for laryngeal microsurgery to achieve positive pressure ventilation and to maintain a steady surgical field. The tube should be placed with clear visualization of the intubation path at the lesion site. Traumatic tracheal intubation may cause cancellation of the surgery.

Procedures for vocal fold paralysis — Vocal cord paralysis is usually due to neurologic injury, either central (eg, dysfunction of brainstem nuclei after head trauma), or peripheral (eg, damage of the vagus, superior laryngeal, or recurrent laryngeal nerves). The most common etiology for vocal cord paralysis is surgical injury of the recurrent laryngeal nerve [26,27].

Unilateral vocal cord paralysis — Unilateral vocal fold paralysis is rarely an immediate life-threatening situation. Surgical options include injection laryngoplasty, medialization laryngoplasty (discussed above), and laryngeal reinnervation. (See 'Laryngoplasty' above.)

Bilateral vocal fold paralysis — Acute onset of bilateral vocal cord paralysis often results in respiratory distress. The patient may be intubated for immediate airway control while a care plan is developed. In some cases, a tracheostomy is performed prior to a definitive surgical procedure. Although a temporary or permanent tracheostomy is often performed for bilateral vocal fold paralysis, conservative management with steroid administration or surgical interventions such as endoscopic laser cordectomy or laser arytenoidectomy may also be used in selected cases.

Intubation is not typically difficult in patients with vocal cord paralysis, since the endotracheal tube (ETT) is usually easily passed between flaccid vocal folds. However, effective mask ventilation may be a challenge due to a significantly narrow laryngeal airway. Therefore, if time permits, adequate preoxygenation should be performed before induction of anesthesia, and apneic oxygenation during laryngoscopy should be considered. (See "Preoxygenation and apneic oxygenation for airway management for anesthesia".)

Laryngeal reinnervation — Laryngeal reinnervation is performed to restore adequate airway capacity after bilateral or unilateral vocal fold paralysis [28,29]; to improve voice quality [30]; or to restore laryngeal sensory function resulting from injury of the recurrent laryngeal nerve (RLN) and its branches, superior laryngeal nerve (SLN), or both. These procedures are performed via a neck incision under general anesthesia with endotracheal intubation. Anesthetic considerations include the following:

●Intraoperative motor nerve monitoring is often used to identify the donor nerve or to test the nerve-muscle integrity. Administration of neuromuscular blocking agents (NMBAs), which are usually used for endotracheal intubation, should be managed such that at least two twitches are apparent with train-of-four twitch monitoring by the time nerve stimulation is performed. Options for administration of NMBAs for intubation in this setting include the use of succinylcholine, use of a nondepolarizing NMBA followed by reversal as need prior to nerve stimulation, or use of high dose remifentanil intubation. (See "Neuromonitoring in surgery and anesthesia", section on 'Neuromuscular blocking agents'.)

●Emergence from anesthesia should include a smooth, rapid awakening and extubation, devoid of coughing, bucking, and straining, to avoid bleeding and a neck hematoma.

●Laryngeal function will be the same as preoperative baseline at the end of surgery, as improvement in nerve function is not immediate, and occurs months after successful reinnervation. Patients with bilateral vocal cord paralysis without a tracheostomy tube in place should be extubated fully awake. Importantly, patients with preoperative respiratory compromise must be monitored closely for respiratory problems during emergence, extubation, and recovery from anesthesia.

●Postoperative pain is generally mild to moderate, given a small operative area, such that acetaminophen or very low dose opioids are usually sufficient for pain control.

Laser lateralization procedures — Laser cordectomy and/or arytenoidectomy are irreversible endolaryngeal procedures used to widen the glottic opening in patients with bilateral vocal fold paralysis. General principles for anesthesia for endolaryngeal procedures are discussed above. (See 'Endoscopic transoral laryngeal surgery' above.)

A laser-resistant ETT is required for laser cordectomy or arytenoidectomy, appropriate for the intended type of laser (see 'Laser-resistant endotracheal tubes' above). For patients who have a tracheostomy in place, the tracheostomy tube should be replaced with a laser resistant ETT after induction of anesthesia.

In some cases, a degree of respiratory compromise persists after laser lateralization procedures, and repeat procedures are required [31]. Postoperative respiratory depression should be avoided. We control the sympathetic response to surgical stimulation with rapid onset, short-acting vasoactive agents (eg, esmolol, nicardipine), rather than high dose opioids, as there is minimal postoperative pain after these procedures. (See 'Intense surgical stimulation' above.)

At the end of surgery, patients should be extubated fully awake, after completely deflating the ETT cuff. Smooth emergence and extubation are particularly important to avoid disrupting the surgical site.

Laterofixation — Laterofixation (ie, suture laterofixation and suture lateralization) of the arytenoid and/or the attached vocal fold using a combination of endolaryngeal and percutaneous approaches has emerged as a reversible alternative surgical approach for bilateral vocal cord paralysis [32]. Anesthesia is managed as it would be for other endolaryngeal procedures. (See 'Endoscopic transoral laryngeal surgery' above.)

LARYNGEAL CANCER SURGERY — The primary anesthetic challenge for patients with laryngeal cancer is airway management. Potential problems include mass effect, local tissue inflammation (picture 8 and picture 1), post radiation edema or tissue fibrosis, and effects of previous surgery (picture 9) (see 'Airway assessment and planning' above). Other significant issues in cancer patients include high levels of anxiety, malnutrition, and hypovolemia. (See 'Prior radiation therapy' above.)

Endoscopic transoral laser microsurgery — General principles for management for endoscopic transoral microsurgery are discussed above (see 'Endoscopic transoral laryngeal surgery' above). Issues specific to cancer surgery are discussed here.

●Hemorrhage is the most common postoperative complication after microlaryngeal surgery for cancer, with a reported incidence 5 to 8 percent. Risk factors for postoperative hemorrhage include advanced cancer pathology and a large area of tumor resection [33,34]. Straining during emergence and cough after extubation may increase postoperative bleeding.

●Most postoperative bleeding is identified in the post-anesthesia care unit (PACU), indicated by coughing and spitting up blood. However, the degree of hemorrhage may be difficult to determine as patients can swallow a significant amount of blood.

●Patients who require surgical re-exploration should be expected to have difficult airways and managed in an operating room unless bedside flexible scope assessment predicts otherwise. Concealed local bleeding can create a hematoma that obstructs the airway.

●Postextubation stridor most commonly occurs in patients who remain overly sedated at the time of extubation, and is rare in patients who are extubated awake. It is usually transient and self-limited. Continuous positive airway pressure (CPAP) is often effective for postextubation stridor in this setting.

●Postoperative pain is usually mild and adequately controlled with acetaminophen, with low dose opioid in the recovery room as necessary, while monitoring closely for respiratory depression. Nonsteroidal anti-inflammatory drugs (NSAIDs) are usually avoided due to bleeding concerns.

Transoral robotic surgery — Transoral robotic surgery (TORS) is performed to resect benign or malignant lesions in hypopharynx or larynx that are too large or complex to be resected with standard microsurgery, and that would otherwise require open surgery. TORS is performed under general anesthesia. These cases typically take much longer than standard microsurgical procedures, and often last several hours (picture 10). Important issues for management of anesthesia include the following:

●We have a low threshold to place an arterial catheter for continuous arterial blood pressure monitoring, to facilitate rapid management of hemodynamic changes and adjustment of anesthetic depth, particularly in patients with cardiovascular disease or prior neck radiation. (See 'Prior radiation therapy' above and 'Intense surgical stimulation' above.)

●For patients without a tracheostomy, nasal intubation with a small diameter endotracheal tube (ETT) is used to maximize oral capacity for surgical equipment. The author routinely uses a 6 mm inner diameter (ID) wire-reinforced ETT (picture 11).

●Deep muscle relaxation (zero twitches with a train-of-four peripheral nerve monitor) is maintained to avoid swallowing and patient movement. (See 'Need for neuromuscular blockade' above.)

●Postextubation airway obstruction is a significant concern after TORS. In some centers, extubation is routinely delayed until the first postoperative day, particularly for procedures that last longer than three or four hours. Prolonged surgical retraction and tissue manipulation can cause airway edema, and resection of a relatively large tissue surface may increase the risk of postoperative airway bleeding. In select cases, a prophylactic tracheostomy is performed.

When a tracheostomy is not indicated, the author usually extubates the trachea at the end of surgery, as long as he and the surgeon agree that there is appropriate hemostasis and no evidence of excessive airway edema. We often place a nasal airway prior to extubation in patients with history of OSA or a large BMI, elevate the head of the bed to 15 to 30 degrees, and extubate the patient fully awake. We have emergency airway equipment immediately available during extubation (including videolaryngoscope), and have the surgeon present for extubation in case an emergency surgical airway is required.

●Transient and mild inspiratory stridor after tracheal extubation is not uncommon. CPAP may be an effective management strategy if stridor occurs. The author uses a Boussignac CPAP system to manage transient airway obstruction (picture 12).

●We routinely monitor ventilation with end-tidal carbon dioxide (ETCO₂) in the PACU in patients who undergo TORS. Patients with airway edema and with impaired consciousness due to residual anesthesia or opioids coupled with elevated carbon dioxide (CO₂) can quickly become unarousable and require emergency airway management.

Laryngeal conservation procedures for cancer — Conservation laryngeal procedures (eg, vertical or horizontal [or supraglottic] hemilaryngectomy, near-total laryngectomy, supracricoid partial laryngectomy) are performed to maximally preserve laryngeal function and avoid a permanent tracheostomy. These procedures are performed under general anesthesia with endotracheal intubation; difficulty with airway management is common (see 'Airway assessment and planning' above). After induction and intubation, the surgeon may work around the ETT or may remove and replace the ETT under direct vision as necessary. Patients are usually extubated at the end of the procedure. Anticipated blood loss for an uncomplicated surgery is 50 to 200 mL (see 'Airway assessment and planning' above). Postoperative pain management is similar to any other open neck procedure.

Total laryngectomy with free flap surgery — The two major anesthetic concerns for patients who undergo total laryngectomy are the possibility of difficulty with airway management and potential for hypotension during anesthetic induction. (See 'Airway assessment and planning' above.)

●Surgical procedure – A total laryngectomy involves en bloc removal of the larynx together with the hyoid bone, thyroid cartilage, and cricoid cartilage. A permanent tracheostoma is formed at the end of surgery. Microvascular free-flap reconstructive surgery is usually performed to repair the large tissue defect. At the author’s institution, total laryngectomy lasts two and one-half to three hours, with approximate blood loss of 100 to 200 ml, and 1500 to 2000 mL intravenous crystalloid administration.

●Airway management – Total laryngectomy requires general endotracheal anesthesia, with induction and initial airway management as appropriate for patient factors. During surgery, the surgeon places an ETT into the trachea and manages further insertion and removal throughout the procedure, until a tracheostoma is created at the conclusion of the procedure.

●Hemodynamic management – We place an arterial catheter preoperatively for continuous hemodynamic monitoring and to facilitate prompt treatment of hypotension and bradycardia. Patients who undergo these procedures are chronically hypovolemic due to dysphagia. Those who have been treated with radiation therapy (RT) may also be at risk for baroreflex dysfunction, which can cause an exaggerated vagal response with stimulation of the distributions of the glossopharyngeal or vagal nerves, or the carotid baroreceptor [10]. (See 'Prior radiation therapy' above.)

The goals for hemodynamic management during free flap reconstruction are to optimize perfusion to the transferred tissue while avoiding the local and systemic adverse effects of fluid overload. We aim for euvolemia with respect to fluid administration, and administer vasoactive agents judiciously based on patient factors and clinical assessment. General anesthetics tend to induce hypotension, which is often counteracted with a combination of fluid administration and vasoactive drugs. Whether to use vasopressors, specifically vasoconstricting drugs, is controversial. The best available evidence suggests that intraoperative use of vasopressors does not increase the risk of flap failure or complications in patients who undergo head and neck surgery. A 2019 meta-analysis of 12 studies (one randomized controlled trial, 11 observational studies) including approximately 8000 patients who underwent free flap surgery reported a lower incidence of flap failure in patients who received vasopressors, compared with those who did not (OR 0.71, 95% CI 0.5-0.99) [35]. In a large, single institution retrospective review of patients who underwent free flap reconstruction for head and neck, breast, extremity, or trunk surgery for cancer, judicious use of phenylephrine, ephedrine, or calcium chloride to maintain blood pressure within 20 percent of baseline was not associated with increased flap failure or pedicle compromise [36].

Evidence for the choice of a specific vasopressor for maintenance of flap perfusion is limited. In one small prospective study of the treatment of postoperative hypotension in patients who had undergone free flap surgery, norepinephrine resulted in improved flap blood flow compared with epinephrine, dobutamine, or dopexamine [37]. Whether these results are applicable to intraoperative use of vasopressors during flap surgery is unknown.

Excessive fluid administration can cause medical complications (eg, pulmonary edema) and edema of the flap and surrounding tissues. In a retrospective study of patients who had free flap surgery for breast reconstruction, intravenous fluid overload was associated with anastomotic thrombosis and flap complications [38].

SUMMARY AND RECOMMENDATIONS

●Airway assessment

•Difficulty with airway management is a primary concern for patients who undergo laryngeal procedures, particularly for laryngeal cancer. Comprehensive airway assessment may include review of imaging, stroboscopy, and/or transnasal flexible laryngoscopy. (See 'Airway assessment and planning' above.)

•Prior neck radiation therapy (RT) can cause tissue fibrosis and edema, which may increase difficulty with airway management. Patients who have received RT are often malnourished and hypovolemic, and are predisposed to hypotension on induction of anesthesia. Neck radiation can also cause baroreflex dysfunction and may predispose patients to hemodynamic instability during anesthesia. (See 'Prior radiation therapy' above.)

●Anesthetic management

•Endoscopic transoral surgery performed with endotracheal intubation requires the use of small endotracheal tubes (ETTs; eg, 5 or 5.5 mm inner diameter [ID] microlaryngeal tube). Tubeless ventilation (eg, apneic intermittent ventilation, jet ventilation [JV], high flow humidified nasal oxygen) is another option for airway and ventilation management. (See 'Airway management and ventilation' above.)

•Laryngoscopy and laryngeal manipulation are intensely stimulating, and may require rapid adjustment of anesthetic depth and/or administration of rapid-acting vasoactive agents (eg, esmolol, nicardipine). (See 'Intense surgical stimulation' above.)

●Common procedures

•Laryngoplasty and thyroplasty – Many laryngoplasty and thyroplasty procedures can be performed with local anesthesia, with or without mild to moderate sedation. Patient cooperation may be required to assess phonation or respiratory function, or to perform stroboscopy. (See 'Laryngoplasty' above.)

•Procedures for vocal fold paralysis – A variety of procedures may be performed to treat vocal fold paralysis. Endoscopic laser procedures and laryngeal reinnervation require general anesthesia. Preoperative respiratory compromise may persist postoperatively; they must be monitored closely for respiratory problems during emergence, extubation, and recovery from anesthesia. (See 'Procedures for vocal fold paralysis' above.)

•Endoscopic transoral surgery for laryngeal cancer – These patients are at risk for postoperative hemorrhage. Patients who require surgical reexploration should be expected to have difficult airways. (See 'Endoscopic transoral laser microsurgery' above.)

•Transoral robotic surgery (TORS) – These are long procedures associated with a high risk of postoperative respiratory obstruction. In some centers, extubation is delayed until the day after surgery. The author extubates patients at the end of the case if there is no evidence of airway edema, with the surgeon and emergency airway equipment in the operating room in case an emergency airway is required, and routinely monitors end-tidal carbon dioxide (ETCO₂) in the post-anesthesia care unit (PACU). (See 'Transoral robotic surgery' above.)

•Total laryngectomy

-Patients who undergo total laryngectomy are often hypovolemic, and are at risk for hypotension during induction of anesthesia. (See 'Total laryngectomy with free flap surgery' above.)

-The goals for hemodynamic management during free flap reconstruction for laryngectomy are to optimize perfusion to the transferred tissue, while avoiding the local and systemic adverse effects of fluid overload. The best available evidence suggests that administration of vasoactive agents does not increase the risk of flap failure or complications. We administer intravenous fluid to achieve euvolemia, and administer vasoactive agents judiciously based on patient factors and clinical assessment. (See 'Total laryngectomy with free flap surgery' above.)