Anesthesia for head and neck surgery

INTRODUCTION — The spectrum of head and neck (H&N) surgery is broad, ranging from simple procedures, such as tonsillectomy to precision laryngologic, neurotologic, and image-guided skull-base surgery, complex obstructive sleep apnea (OSA) surgery, sophisticated transoral robotic surgery (TORS), and major H&N cancer surgery with extensive free-flap reconstruction.

This topic will discuss general principles of anesthetic management for H&N surgery, including airway management specific to these cases. Airway evaluation, management of routine and difficult airways for anesthesia, and anesthesia for tonsillectomy, laryngeal surgery, and thyroid surgery are discussed more fully separately.

●(See "Airway management for induction of general anesthesia".)

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

●(See "Anesthesia for tonsillectomy with or without adenoidectomy in children".)

●(See "Anesthesia for patients with thyroid disease and for patients who undergo thyroid or parathyroid surgery".)

●(See "Anesthesia for laryngeal surgery".)

PREOPERATIVE EVALUATION — A medical history and anesthesia-directed physical examination should be performed for all patients who undergo anesthesia. In anticipation of head and neck (H&N) surgery, we focus the preoperative evaluation on the airway and on those medical conditions that are associated with complications during these procedures.

Assessment of comorbidities — A number of medical conditions are either more likely or of particular concern for patients who undergo H&N surgery.

●For patients with uncontrolled hypertension, cerebrovascular disease, coronary artery disease, chronic renal insufficiency, or advanced liver disease, controlled hypotensive techniques should be avoided, and intraoperative hypotension should be treated aggressively. (See 'Moderate controlled hypotension' below and "Evaluation of cardiac risk prior to noncardiac surgery" and "Anesthesia for the patient with liver disease".)

●Patients with lung disease and ventilation/perfusion (V/Q) mismatch may not be suitable candidates for intraoperative ventilation techniques such as spontaneous ventilation, apneic intermittent ventilation, or jet ventilation. (See 'Ventilation' below and "Evaluation of perioperative pulmonary risk" and "Anesthesia for patients with chronic obstructive pulmonary disease".)

●Obstructive sleep apnea (OSA) is common among patients who undergo H&N procedures, and may be undiagnosed [1]. Patients with OSA are more sensitive to sedatives and opioids and are predisposed to airway obstruction during induction of anesthesia, on emergence, and in the postoperative period [2-4]. (See "Intraoperative management of adults with obstructive sleep apnea" and "Surgical risk and the preoperative evaluation and management of adults with obstructive sleep apnea" and "Postoperative management of adults with obstructive sleep apnea".)

●Lower cranial nerve involvement in neurotologic patients (cranial nerves X, XI, and XII) may increase the risk of aspiration or airway obstruction with induction of anesthesia and complicate difficult airway management. (See "Management of the difficult airway for general anesthesia in adults", section on 'Airway Approach Algorithm'.)

The following issues are of particular concern in patients with H&N cancer:

●Most cases of H&N cancer are associated with tobacco and alcohol use, which predispose patients to cardiopulmonary, liver, and other comorbidities that may affect anesthetic management.

●Patients with H&N cancers are commonly anemic. Hemoglobin or hematocrit and electrolytes should be measured preoperatively, in addition to other laboratory tests, as indicated.

●Radiation for H&N cancers can result in dry mouth, airway swelling, dysphagia, poor oral intake, and dehydration, which may predispose these patients to hypotension with induction of anesthesia. Radiation may also make tracheal intubation and mask ventilation difficult by causing tissue fibrosis, loss of tissue compliance, restricted mouth opening and neck extension, and glottic and epiglottic edema [5].

Airway evaluation — Difficulty with airway management is more common for patients who undergo H&N procedures than for many other surgical patients. Prior anesthesia records should be reviewed, focusing on airway management. Comprehensive preoperative airway evaluation should include assessment of predictors of difficult/impossible mask ventilation, their association with difficult direct laryngoscopy (DL), and predictors of difficult videolaryngoscopy (VL).

A history of difficult tracheal intubation is one of the most important predictors of difficult airway management [6-9], though a prior easy intubation does not guarantee subsequent uneventful airway management in H&N patients, due to progression of the underlying disease.

Incidence of airway difficulty — Estimates of the incidence of airway difficulty in these patients come from a number of sources.

●For the Fourth National Audit Project (NAP4) from the Royal College of Anaesthetists and the Difficult Airway Society in the United Kingdom (UK), reports of major airway complications were prospectively collected in nearly three million anesthetized patients throughout the UK [10]. H&N patients comprised nearly 40 percent of cases with airway management-related complications and almost 75 percent of cases where emergency surgical airway (ESA) was required for "cannot intubate, cannot ventilate" (CICV) situations [11,12].

●A higher incidence of ESA in H&N patients was further confirmed in a retrospective study of 452,461 patients in Danish Anaesthesia Database [13]. In this study, 20 of the 27 patients who required ESA were undergoing ear nose and throat (ENT) surgery and three additional patients had pathology of the neck or oropharynx. The overall incidence of ESA in ENT patients was recorded at 1.6 events per thousand, which was 27 times higher than in the general surgical population (0.06 per thousand).

●Several large studies have reported that difficult tracheal intubation, defined as three or more attempts at direct laryngoscopy, may occur in up to 7 to 9 percent of H&N cases [14-16], which is at least two to four times higher than in the mixed surgical population [17-20].

●H&N cancer patients are at highest risk for difficult airway management among those having H&N surgery.

•A study of 1200 surgical patients reported difficult intubation in 12 percent of H&N cancer patients, compared with 3.5 percent of those who underwent noncancer H&N surgery and 2 percent of general surgical patients [14].

•In NAP4, of the 21 cases of severe airway difficulty on induction of anesthesia, 13 occurred in patients with upper airway tumors [11].

•In a small prospective observational study of intubation in 19 patients who underwent head and neck surgery for cancer, difficult direct laryngoscopy occurred in 53 percent of patients [21].

•Data from another prospective observational trial of 44 patients similarly indicate low (53.8 percent) first pass success rate (FPS) with DL in H&N cancer patients, with associated high risk of periprocedural hypoxemia (68 percent incidence of difficult bag mask ventilation and 34 percent incidence of desaturation [22].

●The incidence of difficult videolaryngoscopy (VL) is also significantly higher in patients with H&N pathology than in other patients and may be associated with up to a 37 percent incidence of complications [22]. A prospective observational study of 92 patients with predicted difficult airways due to H&N pathology found a high incidence of inability to obtain a view of the glottis even with acute-angle video laryngoscopy, particularly in patients with airway masses [23]. The incidence of Grade 3 or 4 view of the larynx ranged between 30.4 and 40.2 percent depending on the device used. The reported range of First pass success with VL in H&N cancer patients is from 58 to 87.5 percent, depending on the nature of the pathology and the degree of airway compromise [22,23].

Some identified predictors of difficulty with VL may assist a clinician devise an optimal airway management plan. In a retrospective review of over 2000 GlideScope intubations, the strongest predictors of GlideScope failure were conditions that are likely to exist in H&N patients, including prior neck radiation, abnormal neck anatomy, and airway masses (table 1) [24]. In another study of 1100 patients with predicted difficult DL, there were 300 patients with difficult acute-angle VL (ie, GlideScope or C-Mac with D blade) [25]. Predictors of difficult VL included the sniffing head position for laryngoscopy (compared with neutral position), intubation by an attending anesthesiologist, undergoing cardiac or otolaryngologic surgery, and limited mouth opening.

Airway examination — We perform a systematic and comprehensive preoperative airway assessment, starting with a careful history and the physical characteristics included in the American Society of Anesthesiologists (ASA) 11-point bedside airway assessment tool (table 2) [26]. While we routinely perform these tests, their value is limited in patients with H&N pathology since they do not account for risk of aspiration, lower airway problems, the severity of upper airway disease, or base of tongue pathology (eg, lingual tonsillar hypertrophy), all of which may affect the degree of airway difficulty.

Postradiation changes in the neck and decreased mandibular protrusion are common in patients with H&N pathology, and advanced disease may make an ESA difficult or impossible.

Signs and symptoms of airway obstruction should be elicited, including dyspnea at rest or on exertion, dysphagia, stridor, cough, and voice changes. A muffled voice may indicate supraglottic disease, whereas glottic lesions often result in a coarse, scratchy voice. Physical findings may include hoarseness; agitation; and intercostal, suprasternal, and supraclavicular retraction.

Drooling, dysphagia, and expiratory snoring are the signs of marked pharyngeal restriction [27,28], but inspiratory stridor at rest represents the most worrisome sign, suggesting a reduction in airway diameter at the supraglottic, periglottic, or glottic level of at least 50 percent [29,30].

Airway compromise in H&N patients may also involve the lower airways. Tracheal or tracheobronchial narrowing typically causes expiratory stridor, whereas biphasic inspiratory-expiratory stridor usually results from obstructive subglottic disease [31].

Special attention should be paid to risk factors for impossible mask ventilation, difficult mask ventilation, and their association with difficult direct laryngoscopy (table 3 and table 4).

The airway examination and risk factors for difficult airway management are discussed separately (table 1 and table 3 and table 4). (See "Airway management for induction of general anesthesia", section on 'Airway assessment' and "Management of the difficult airway for general anesthesia in adults", section on 'Recognition of the difficult airway'.)

Endoscopy and imaging studies — The airway anatomy and extent of disease is usually comprehensively evaluated preoperatively by routine chest radiography, computed tomography (CT), magnetic resonance imaging (MRI), and flexible nasal laryngoscopy (ie, nasal endoscopy). The results help define the location, size, spread, and vascularity of obstructive lesions, the degree of obstruction, the mobility of the vocal cords, and the extent of laryngeal and tracheal deviation or compression [31-33]. In some cases, preoperative examination of flow-volume loops may be helpful [34]. (See "Evaluation of perioperative pulmonary risk".)

In patients with H&N cancer, airway imaging and nasal endoscopy are required for assessing airway management options, especially if symptoms of airway obstruction are present [12,35]. For high-risk patients, these results should be reviewed and discussed jointly with the surgeon [35].

Preoperative nasal endoscopy is routinely performed by the H&N surgeon, but with sufficient practice, preoperative endoscopic airway evaluation (PEAE) can be performed by the anesthesiologist when necessary. In H&N cancer patients PEAE can provide precise information about the upper airway and laryngeal anatomy and upper airway dynamics to facilitate formulation of airway management strategy [36]. It can also help determine the feasibility of supraglottic airway (SGA) placement after induction of general anesthesia. (See 'Supraglottic airways' below.) Even when used for patients who undergo non-cancer related H&N surgery, PEAE can help improve predictability of difficult intubation and improve upon the routine bedside airway evaluation [37].

SURGICAL CONSIDERATIONS — The plan for anesthesia management for H&N surgery requires especially close coordination with the surgeon (table 5).

●Airway management strategy – For high-risk patients, the strategy for airway management should be formulated with the surgeon, including review of preoperative imaging studies and endoscopy, selection of airway management device, route for tracheal intubation (TI), use of jet ventilation, and backup strategies, including preparation for a surgical airway in selected cases. (See 'Airway management strategy' below.)

●Shared airway – The airway is shared by the anesthesiologist and the surgeon during many H&N procedures. For the majority of cases, immediate access to the patient’s airway by the anesthesiologist is either difficult or impossible.

•During oral and intranasal surgery, the airway must be protected from blood, debris, and irrigation fluid; this may require placement of a throat pack. Endotracheal tubes (ETTs) must be appropriately sized and adequately secured to avoid accidental displacement or extubation intraoperatively.

•The size and type of ETT should be discussed with the surgeon.

-A 6-mm internal diameter (ID), wire-reinforced, flexible ETT is frequently selected for intraoral surgery.

-Nasal intubation is routinely required for base of the tongue (BOT) surgery, transoral robotic surgery (TORS), orthognathic surgery, and maxillomandibular advancement (MMA) for obstructive sleep apnea (OSA), and may be requested by the surgeon for parotidectomy and some dental procedures. A nasal ETT must be appropriately sized to assure adequate depth of tracheal placement to avoid circuit leak, and must be properly secured to prevent pressure against the nasal ala. A 6-mm ID microlaryngeal tube (MLT) is frequently required to facilitate surgical access for TORS.

-For microlaryngeal surgery, a small-sized ETT (eg, a 5-mm ID MLT) is commonly used. For these cases, the ETT should be moved to the left corner of the patient's mouth to facilitate introduction of surgical instruments. It must be securely taped to the lower jaw to avoid outward displacement of the ETT when the mouth is opened and the neck is extended for laryngeal suspension.

-Specialized laser-safe and nerve integrity monitor (NIM) ETTs may be used for specific procedures.

-Supraglottic airways (SGAs) may be effectively used and even preferred instead of ETTs for some of the H&N procedures to facilitate smooth emergence from anesthesia.(See 'Smooth extubation strategy' below.)

•The anesthesia breathing circuit should be configured to allow unrestricted surgical access. As an example, the breathing circuit should connect to the ETT from the head of the operating table over the top of the patient's head during TORS, orthognathic, or MMA surgery.

●Still surgical field – Many H&N procedures require a completely still surgical field for precision dissection (eg, otologic and neurotologic surgery, laser otolaryngologic surgery, functional endoscopic and cranial-base surgery, TORS). For these cases, patient movement, motion associated with monitoring devices (eg, blood pressure [BP] cuff inflation), and accidental OR table movements must be avoided. The surgeon should be notified before any action on the part of the anesthesiologist that may interfere with precision surgery. For precision endoscopic procedures (eg, middle ear surgery), we typically place the BP cuff on the patient's side opposite the surgeon, to avoid iatrogenic tremor-induced interference with microdissection. (See 'Prevention of patient movement' below.)

●Neuromonitoring – Neuromonitoring may be used during H&N procedures and may preclude the administration of neuromuscular blocking agents (NMBAs).

●Fire risk – The risk and prevention of airway fire should be explicitly discussed with the surgeon and operating room nurses preoperatively, and the "laser time out" should be observed in the OR. Airway fire is a rare but potentially devastating event that may occur whenever an oxidizing agent (eg, oxygen [O₂] or nitrous oxide [N₂O]), a fuel source (eg, prep solution, endotracheal tube), and an ignition source (eg, laser, electrocautery) are present. Airway fire is discussed more fully separately. (See "Fire safety in the operating room", section on 'Incidence and impact of operating room fires' and "Fire safety in the operating room", section on 'Fire in the airway'.)

ANESTHESIA MANAGEMENT — The objectives and strategies for anesthesia for head and neck (H&N) procedures are shown in a table (table 5).

Choice of anesthetic technique — For most H&N procedures, general anesthesia is the preferred technique. Compared with monitored anesthesia care (MAC), general anesthesia protects the patient's airway, assures adequate gas exchange, abolishes patient movement, reliably provides amnesia, and avoids distracting the surgeon.

MAC may be performed for selected H&N procedures. As an example, laryngeal framework surgery may require spontaneous ventilation and a responsive patient. MAC without immediate access to the patient's airway may be challenging, given the fluctuating level of surgical stimulation.

Monitoring — Standard American Society of Anesthesiologists (ASA) monitors (eg, blood pressure [BP], electrocardiography, O₂ saturation, capnography, and temperature) are usually sufficient during H&N surgery, even when controlled hypotension is used. Additional monitors may be added as follows:

●Continuous arterial blood pressure monitoring – An intra-arterial catheter should be placed, as required by the patient's medical condition (eg, significant coronary artery disease [CAD], hypertension, cerebrovascular disease, chronic renal insufficiency [CRI]), the potential for hemodynamic instability (eg, carotid baroreceptor responses during extensive neck operations, brainstem and trigeminal reflexes during skull-base and neurotologic procedures), the need for free flap perfusion monitoring (eg, during H&N free flap reconstructions), or the expectation of significant blood loss.

●Central venous catheter – A central venous catheter (CVC) is occasionally placed when there is potential for significant hemodynamic instability to allow rapid central administration of vasoactive drugs. Central venous pressure (CVP) monitoring is usually reserved for patients with significant CRI presenting for major and prolonged H&N surgery associated with potentially significant fluid shifts.

●Processed electroencephalogram – We use processed electroencephalogram (EEG) monitoring routinely to help assess the depth of anesthesia and to guide anesthetic drug dosing, particularly in the following situations:

•During total intravenous anesthesia (TIVA). (See "Accidental awareness during general anesthesia", section on 'Total intravenous anesthesia'.)

•For patients with increased sensitivity to anesthetic medications (eg, older or frail patients).

•When neuromuscular blocking agents (NMBAs) are avoided, to assure adequate depth of anesthesia and avoid patient movement.

Processed EEG monitoring may also be helpful for detecting brain hypoperfusion during intraoperative hypotension or an acute intracerebral thrombotic event during complex neck dissection.

●Neuromonitoring – If neuromonitoring is used during H&N procedures (eg, electromyographic [EMG] monitoring of facial nerve), the anesthetic technique may require modification. The effects of anesthetics on neuromonitoring are discussed separately. (See "Neuromonitoring in surgery and anesthesia".)

Airway management strategy — A successful airway strategy requires a pre-formulated plan for managing difficult, delayed, and failed intubation and for achieving and maintaining adequate ventilation, oxygenation, and protection against aspiration (algorithm 1 and table 6) [38]. The optimal airway management approach depends on the surgical procedure, location of the lesion, patient symptoms, acuity of the situation, and the patient's tolerance of the airway management procedure. It may also be dictated by the anesthesiologist's skill set and equipment availability.

Patients who undergo complex H&N procedures are most appropriately cared for in high-volume centers with experienced staff that includes anesthesiologists with special expertise in these cases and complex airway management. A prospective study of 150 intubations in patients with difficult airways due to H&N pathology reported that anesthesiologists specializing in H&N procedures achieved faster intubation, better patient oxygenation, and fewer airway plan changes than nonspecialist anesthesiologists [15].

The optimal strategies for airway management for high-risk patients should be discussed with the surgeon, who should be present for all aspects of airway management.

The overall approach to difficult airway management is discussed more fully separately. (See "Management of the difficult airway for general anesthesia in adults".)

Airway management issues specific to H&N procedures are discussed here.

Laryngoscopy technique — Airway management may deteriorate after single or especially repeated attempts at direct laryngoscopy (DL), particularly in patients with H&N pathology [11]. H&N tumors can cause airway distortion and can be friable, leading to bleeding, fragmentation, airway soiling, and rapid edema formation with laryngoscopy. If DL is chosen as a primary approach to tracheal intubation, multiple attempts should be avoided to avert total airway obstruction.

Videolaryngoscopy (VL) should be strongly considered as the primary intubation technique for H&N patients to increase the FPS. (See "Video laryngoscopes and optical stylets for airway management for anesthesia in adults", section on 'Intubation success and outcomes with video laryngoscopes'.)

However, similar to any airway management technique, VL may be difficult or fail, and alternative airway strategies should be planned (table 1). (See 'Incidence of airway difficulty' above.)

Endotracheal intubation by the surgeon — If DL or VL fails, the surgeon may be able to intubate using the operating laryngoscope or rigid bronchoscope [26,39-41]. The anterior commissure scope may afford a view of the glottis when other techniques fail, and an endotracheal tube (ETT) or a bougie introducer can be inserted through its lumen [42].

The surgeon can also use a rigid bronchoscope for ventilation after failed intubation or acute airway obstruction resulting from foreign bodies, hemoptysis, or tumors [43,44].

Flexible scope intubation — Both awake and asleep flexible scope intubations have relatively high failure rates in patients with H&N pathology, with reported failure rates between 9 and 60 percent [11,15].

The most common reasons for failure of flexible scope intubation in these patients include inability to identify the glottis, difficulty passing the scope, bleeding, and airway obstruction [11]. (See "Flexible scope intubation for anesthesia".)

Optical and video stylets — The intubation stylets (eg, Bonfils, Shikani, SensaScope, Clarus Video System) may offer an advantage over flexible scopes in patients with H&N cancer. These rigid devices may bypass mobile supraglottic and glottic masses in situations when a flexible scope will not pass. (See "Video laryngoscopes and optical stylets for airway management for anesthesia in adults".)

Supraglottic airways — Supraglottic airways (SGAs) may be difficult to insert or seat in patients with H&N pathology. History of neck radiation; limited mouth opening; and glottic, hypopharyngeal, and subglottic pathology, all of which may be present in these patients, are predictors of difficulty with SGA ventilation. (See "Management of the difficult airway for general anesthesia in adults", section on 'Recognition of the difficult airway'.)

●Laryngeal mask airways (LMAs) – For H&N surgery, we suggest using a second-generation SGA rather than a first-generation device to improve ventilation and reduce the risk of aspiration. (See "Supraglottic devices (including laryngeal mask airways) for airway management for anesthesia in adults", section on 'Choice of supraglottic airway'.)

We use a bougie introducer-assisted insertion technique for most second-generation SGAs, and specifically for the LMA ProSeal, to maximize the first-pass success rate and to assure optimal esophageal and laryngeal seals [45].

The LMA Fastrach, which is an intubating LMA (iLMA), provides excellent ventilation and achieves a 92 to 94 percent success rate of blind tracheal intubation (TI) in patients with anticipated difficult airways [46,47]. In patients with glottic or infraglottic pathology, blind TI intubation should be avoided. Instead, a flexible scope can be passed through the iLMA and used to exchange it for an ETT. (See "Supraglottic devices (including laryngeal mask airways) for airway management for anesthesia in adults", section on 'Use of flexible intubating scope'.)

●Tubular SGAs – Tubular SGAs, such as the Combitube and laryngeal tubes (LTs), are especially useful in H&N patients with limited mouth opening or significant upper airway bleeding or regurgitation, when rapid control of the airway is necessary. These devices are more commonly used in prehospital emergency airway management and in the emergency department (ED). In anesthetized patients, the LT may provide an advantage over mask ventilation for some patients with H&N pathology. One small study reported successful ventilation with an LT in 22 of 23 patients with airway tumors, compared with 15 patients who were successfully mask ventilated [48]. We have successfully used LTs for some patients with small mouth openings and predictors of difficult mask ventilation for ventilation and as a bridge to tracheal intubation. (See "Extraglottic devices for emergency airway management in adults", section on 'Combitube'.)

●Use of the SGA as a primary ventilatory device – The use of the SGA in lieu of ETT may be highly preferred for many elective H&N surgical procedures, such as ear surgery, nasal and intranasal surgery, and facial cosmetic surgery, for which smooth emergence from anesthesia is essential. (See 'Smooth extubation strategy' below.)

Both retrospective and prospective studies on the use of LMA (or flexible LMA [FLMA]) as a primary ventilatory device in H&N surgery demonstrate decreased incidence of upper airway trauma and adverse respiratory events, eliminating the need for the use of NMBAs, improved maintenance of a stable plane of anesthesia and controlled hypotension, and smoother and faster emergence from anesthesia [49-57].

•For the otologic surgery, we prefer to use a second generation SGA, most commonly LMA-Proseal or LMA-Supreme, to assure proper SGA positioning and function. (See "Supraglottic devices (including laryngeal mask airways) for airway management for anesthesia in adults", section on 'Choice of supraglottic airway'.)

The use of these devices does not interfere with the surgical field, as the patient's head is not manipulated until after the end of surgery for the dressing application.

•For nasal, intranasal, and facial cosmetic surgery we prefer to use FLMA to facilitate surgical access. The properly placed FLMA creates a reliable oropharyngeal seal, adequately protecting the lower airway from blood, secretions, irrigation fluid, and surgical debris [58-60], eliminating the need for the use of a throat pack by the surgeon [50,57,61].

•When using SGA as the primary airway for elective H&N surgery, proper device position and function should be confirmed before surgery starts. Special attention shall be directed to assuring the device's proper positioning and function before the surgery commences. Safety considerations include standard SGA insertion technique, adequate SGA ventilatory performance, and adequate airway protection from above and below SGA cuff (ie, adequate airway seal pressure and absent gastric insufflation during positive pressure ventilation [PPV]). We prefer to use PPV through the SGA (usually, a pressure-controlled ventilation mode) intraoperatively. (See "Supraglottic devices (including laryngeal mask airways) for airway management for anesthesia in adults", section on 'Pressure-controlled ventilation'.)

•A retrospective study of 685 patients has demonstrated an overall 92.6 percent success rate of the use of FLMA when the above strict safety precautions were followed [57].

Combined intubation techniques — The combined endoscopy technique of using VL with a flexible scope or optical stylet is increasingly common in difficult and complex airway management. In a randomized trial of 180 patients comparing the use of the GlideScope alone with the GlideScope-flexible scope combination in patients with difficult airway, the latter resulted in 26 percent higher FPS, shorter intubation time and 91 percent reduction in airway injury [62]. VL provides an enlarged view of the glottis and facilitates manipulation of the flexible scope or optical stylet in patients with distorted anatomy or airway tumors. The combined technique allows continuous visualization of the intubation procedure both from above and below the vocal cords, with less chance of tumor disturbance and immediate confirmation of proper ETT tracheal placement and position.

Oxygenation strategies — Oxygenation-centered airway management is critical for H&N patients, who present with a higher incidence of failed tracheal intubation and "cannot intubate, cannot ventilate" (CICV) situations.

The use of high flow nasal oxygen (transnasal humidified rapid insufflation ventilatory exchange [THRIVE]) prolongs apnea time, and should be strongly considered in anticipated difficult airway management [63,64] (see "Preoxygenation and apneic oxygenation for airway management for anesthesia", section on 'Heated humidified high flow nasal oxygen'). The placement of a transtracheal jet ventilation (TTJV) catheter or cannula before induction of anesthesia for providing tracheal oxygen (O₂) insufflation or high-frequency TTJV [65,66] can be considered in complex cases.

Alternatively, the Arndt cricothyroidotomy catheter can be placed. Its 3-mm internal diameter (ID) lumen allows ventilation using a low-pressure gas source, such as an anesthesia breathing circuit or Ambu bag [67].

Surgical airway — A tracheostomy may be planned as the primary intubation strategy for patients who are expected to have significant airway compromise after surgery.

Most H&N surgeons prefer to perform tracheostomies under controlled conditions, after induction of anesthesia, to avoid airway trauma, tumor disturbance, and tracheostomy tube displacement or obstruction [15]. The suitability of this plan depends on the predicted difficulty of airway management after induction of anesthesia.

If awake tracheostomy is deemed necessary, it should be performed under local anesthesia without sedation. An alternative is an awake dilator cricothyroidotomy [15,68].

For emergency airway management, surgical cricothyroidotomy is strongly preferred over percutaneous access through the cricothyroid membrane. In the Fourth National Audit Project (NAP4) of airway complications in the United Kingdom, emergency transcutaneous cannula cricothyroidotomy failed in 60 percent of H&N patients [11,12].

Induction of anesthesia — A variety of medications and techniques can be used for induction of anesthesia and are chosen based on patient factors.

Intravenous versus inhalation induction — For most adults, intravenous (IV) induction is performed with propofol. Inhalation induction may be warranted in selected cases but may frequently fail. (See "Induction of general anesthesia: Overview".)

Inhalation induction is of limited value in complex H&N pathology, especially in patients with advanced upper airway obstruction. In the NAP4, inhalation induction failed in 12 of 16 (75 percent) of H&N patients with compromised airways, and in nearly all these patients (11 of 12), spontaneous ventilation became impossible [11]. (See 'Incidence of airway difficulty' above.)

Inhalation induction should be considered for patients with H&N cancer only after consultation with the surgeon and evaluation of the predicted difficulty with mask ventilation, and may be best reserved for patients with noncollapsing lesions [15]. Inhalation induction may be highly problematic for patients with difficult mask ventilation.

Neuromuscular blocking agents — An NMBA is usually administered during induction to facilitate mask ventilation and tracheal intubation. When neuromonitoring is used, the administration of NMBAs should be avoided intraoperatively. (See "Neuromonitoring in surgery and anesthesia", section on 'Neuromuscular blocking agents'.)

Positioning — Positioning for H&N surgery requires meticulous attention to detail. General concerns include the following:

●The patient's arms are usually tucked in by the sides. Pressure points should be padded, as should all plastic connectors and the other parts of IV tubing and monitoring devices to prevent skin pressure and nerve injury.

●The head of the operating table is usually turned 90 or 180 degrees away from the anesthesiologist, preventing immediate access to the airway. The ETT should be effectively secured to prevent accidental extubation or ETT pullback. The breathing circuit should be firmly attached to the ETT and supported to prevent disconnection.

●The patient's eyes should be adequately protected. We cover the eyes with occlusive dressing to keep the lids closed and prevent skin preparation solution from entering the eyes. In addition, protective goggles should be placed for surgeries involving heavy instrumentation around the patient's face (eg, during transoral robotic surgery).

●The operating table may be placed in a steep lateral position during otologic and neurotologic surgery. We apply three straps, one each over the chest, pelvis, and legs, to prevent patient shifting on the operating table.

Maintenance of anesthesia — Many H&N procedures involve delicate surgery on complex, reflexogenic anatomy. A variety of inhalation and IV anesthetic agents may be administered, with the following goals:

●Maintenance of a stable plane of anesthesia during varying degrees of stimulation

●Minimizing bleeding to maintain a clear, dry surgical field

●Maintenance of a still surgical field

●Prevention of postoperative nausea and vomiting (PONV)

●Planning for smooth emergence

●Preparation for rapid recovery and fast-track discharge, where appropriate

Choice of anesthetic agents — Inhalation anesthetics, IV anesthetics, and a combination of both classes of anesthetic agents may be administered for the maintenance of anesthesia for H&N surgery. For patients at high risk of postoperative nausea and vomiting (PONV), and for those who undergo H&N procedures that are particularly emetogenic (eg, middle ear surgery, neurotologic surgery), propofol-based anesthesia may reduce the incidence of PONV. Our technique of choice for most H&N procedures is total intravenous anesthesia (TIVA) and target-controlled infusion (TCI) of propofol and opioids.

Total intravenous anesthesia — We prefer TIVA with propofol and an opioid with intraoperative processed EEG monitoring for most H&N procedures. For most surgical procedures that are associated with mild-to-moderate postoperative pain (table 7), TCI with propofol 3 to 3.5 mcg/mL and remifentanil 2 to 5 ng/mL should be appropriate, especially if neuromuscular block is maintained or if an LMA is used [69-72]. Doses should be modified for older patients and for patients with comorbidities.

Advantages of this technique include the following:

●The synergism between propofol and opioid (ie, remifentanil, sufentanil, fentanyl, and alfentanil) allows quick titration of anesthesia to the desired clinical effect [73,74].

●TIVA with propofol/opioid facilitates intraoperative hemodynamic control and rapid recovery from anesthesia.

●TIVA with propofol/opioid produces profound depression of pharyngeal and laryngeal reflexes and muscle tone [75] and suppresses the hormonal stress response to H&N surgical procedures [76], thereby facilitating induced hypotension. (See 'Moderate controlled hypotension' below.)

●Compared with inhalation anesthesia, TIVA may result in faster early recovery after surgery and a reduction in PONV [58,77-81].

●TIVA is almost always used during jet ventilation or an intermittent apnea technique for laryngologic surgery.

TCI technology is not available in the United States.

Opioids during maintenance of anesthesia — We administer opioids by infusion during H&N surgery as an integral component of anesthesia maintenance. We choose the drug and dose based on the expected degree of intraoperative stimulation and postoperative pain, duration of surgery, patient factors (eg, opioid-naïve or not), and the individual surgical technique (table 7).

The advantages of opioid-based anesthetic techniques for these patients include the following (table 8):

●Suppresses airway reflexes

●Decreases requirement for other anesthetic agents

●Aids controlled hypotension

●Decreases patient movement

●Facilitates processed EEG monitoring

●Facilitates neuromonitoring

●Allows smooth emergence from anesthesia

●Improves postoperative pain control

Continuous opioid infusion may decrease the total dose of opioid administered and improve hemodynamic stability compared with intermittent boluses [69,82,83].

Remifentanil is an ultrashort-acting opioid that can be administered at high doses to achieve profound intraoperative analgesia without postoperative residual effects [59]. Compared with fentanyl [60] and alfentanil [84-87], remifentanil may result in increased hemodynamic stability and faster recovery from anesthesia. The choice of opioids, stratification according to the surgical procedure, and infusion doses are shown in a table (table 7) [58,60,69,73,77,84,88-104]. (See "Perioperative uses of intravenous opioids in adults: General considerations".)

Inhalation anesthetics — When inhalation anesthesia is used, sevoflurane may be preferred for outpatient surgery compared with desflurane and isoflurane. Sevoflurane is less of an airway irritant and is associated with less postoperative coughing than desflurane [105,106], and early recovery from anesthesia may be more rapid with sevoflurane than it is with isoflurane [89,106].

Inhalation anesthetics are associated with increased PONV compared with propofol-based anesthesia. We routinely administer multimodal prophylaxis for PONV for all patients who undergo H&N surgery. (See 'Prophylaxis for postoperative nausea and vomiting' below.)

If nitrous oxide (N₂O) is indicated clinically, its use should be discussed with the surgeon during middle ear procedures. N₂O diffuses into closed spaces, including the middle ear in patients with eustachian tube dysfunction, and can displace tympanic grafts and other middle ear structures [107]. N₂O also supports combustion and should be avoided when airway fire risk is high. (See "Fire safety in the operating room", section on 'Risk prevention: High-risk procedures'.)

Moderate controlled hypotension — Controlled hypotension (ie, systolic blood pressure [BP] below 100 mmHg or mean arterial pressure of 60 to 70 mmHg) is desirable for many H&N procedures (eg, middle ear surgery, neck dissection, endoscopic procedures, etc) to maintain a bloodless surgical field. The need for controlled hypotension and the goal BP should be discussed with the surgeon, considering patient comorbidities. Controlled hypotension should be avoided in patients with uncontrolled hypertension, cerebrovascular disease, significant coronary artery disease, chronic renal insufficiency, or advanced liver disease.

A variety of medications can be administered to induce hypotension. In practice, remifentanil infusion with either propofol or inhalation anesthesia usually results in the desired degree of hypotension without administration of vasoactive medications [108,109]. The incidence of rebound hypertension and tachycardia with the use of remifentanil appears to be low.

Other medications that have been used to induce hypotension during H&N surgery include sodium nitroprusside, beta blockers (eg, esmolol, labetalol, metoprolol), calcium channel blockers (eg, clevidipine, nicardipine), alpha₂-adrenoreceptor agonists (eg, dexmedetomidine), magnesium sulfate, and potent inhalation anesthetics (eg, sevoflurane, isoflurane, desflurane) [72,108-113].

Prevention of patient movement — NMBAs may be administered to prevent patient movement during many delicate H&N procedures. When NMBAs must be avoided (eg, neuromonitoring for thyroid and parathyroid surgery), deeper anesthesia is frequently required to prevent patient movement. Highly titratable opioid infusion (eg, remifentanil) can help maintain a stable level of anesthesia without affecting neuromonitoring. (See 'Opioids during maintenance of anesthesia' above.)

Facial nerve monitoring is often used during craniofacial, middle ear, and skull-base surgery. Facial nerve electromyographic (FNEMG) monitoring used by the surgeon may alert the anesthesiologist to a decrease in anesthetic depth and may predict patient movement [90,114]. A study including 60 patients who underwent craniofacial or skull-base surgery reported that FNEMG changes predicted patient movement better than changes in the bispectral index (BIS; processed EEG) monitor [90].

Ventilation — Several specialized ventilation strategies can be used to improve surgical access during laryngologic surgery. Supraglottic, infraglottic, transtracheal jet ventilation (TTJV), THRIVE, and apneic intermittent ventilation are some of the possibilities.

Jet ventilation — Both low- and high-frequency jet ventilation (HFJV) can be used for laryngologic surgery, depending on JV technique (below). HFJV is utilized more often in general, and is used exclusively for infraglottic and transtracheal routes. HFJV is usually initially set at 150 counts/minute (CPM; range 100 to 300 CPM), delivering tidal volumes as small as 1 to 3 mL/kg. HFJV results in minimal laryngeal motion and a quiet surgical field without the need to interrupt ventilation. However, carbon dioxide (CO₂) retention is possible since dead space ventilation is increased compared with lower-frequency, higher-tidal-volume ventilation.

JV requires meticulous attention to detail and familiarity with the specialized equipment to avoid barotrauma. In particular, airway patency must be continuously maintained to allow exhalation.

JV can be performed with infraglottic, supraglottic, or transtracheal techniques.

●Infraglottic JV – Infraglottic JV is used most commonly for airway surgery. A 3- to 4-mm outer diameter (OD), laser-resistant double lumen catheter or a metal jet cannula is placed in the trachea using laryngoscopy [115-119]. End-tidal CO₂ (ETCO₂) can be intermittently monitored via one of the catheter lumens. Infraglottic JV can also be used through a rigid bronchoscope deployed to bypass obstructing airway lesions, or for rescue ventilation.

●Supraglottic JV – For supraglottic JV, the jet nozzle is positioned above the glottic opening, resulting in a very low risk of barotrauma. Supraglottic JV is usually administered through the operating laryngoscope deployed by surgeon, and provides a completely unobstructed view of the larynx. However, the movement of the vocal cords is increased compared with the infraglottic approach, and ETCO₂ cannot be measured. The jet must be directed precisely at the glottis for effective, safe ventilation.

●Transtracheal JV – The larynx is bypassed from below by a long catheter or Ravussin-type cannula placed through the cricothyroid membrane [116,118,120].

THRIVE — Many conventional, non-laser laryngologic surgical procedures up to 30 to 40 minute duration can be performed on selected patients using transnasal humidified rapid insufflation ventilatory exchange (THRIVE) as the primary ventilatory technique. THRIVE provides both apneic oxygenation and apneic ventilation (a certain degree of CO₂ elimination), and affords the surgeon with a fully enlarged, completely unobstructed and still surgical filed [63,121-127]. This greatly facilitates surgical access, with a potential to improve patient outcomes [121]. A close communication between the surgeon and the anesthesiologist is required during THRIVE, and the use of this technique may be best reserved, at least initially, to dedicated H&N anesthesia team(s). (See "Preoxygenation and apneic oxygenation for airway management for anesthesia", section on 'HFNO for laryngologic surgery' and "Anesthesia for laryngeal surgery", section on 'High flow nasal oxygen'.)

Intermittent apneic 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.

Prophylaxis for postoperative nausea and vomiting — Patients who undergo H&N surgery should receive aggressive prophylaxis for PONV and postdischarge nausea and vomiting (PDNV). Retching and vomiting can increase venous pressure in the H&N and result in postoperative bleeding, hematoma formation, and graft disruption. We use a multimodal approach to prophylaxis, consisting of TIVA with intraoperative 5-HT₃ antagonist (eg, ondansetron 4 to 8 mg IV), dexamethasone (8 to 10 mg IV), and multimodal pain control to minimize opioid requirement. We place a scopolamine patch for particularly high-risk patients. (See "Postoperative nausea and vomiting".)

Plan for postoperative pain control — The plan for control of postoperative pain begins intraoperatively, and in some cases, preoperatively. In our practice, intraoperative opioid choice and administration is largely based on the expected degree of postoperative pain (table 7).

A multimodal approach to pain control helps to minimize the use of postoperative opioids, and may include perioperative use of acetaminophen and/or gabapentin, and nonsteroidal antiinflammatory drugs (NSAIDs). (See 'Opioids during maintenance of anesthesia' above and "Approach to the management of acute pain in adults".)

In some cases, local anesthetic infiltration or peripheral nerve blocks may be used for H&N cases for postoperative pain control.

Emergence from anesthesia — Emergence from anesthesia for H&N patients should include a smooth, rapid awakening and extubation, devoid of coughing, bucking, and straining. BP should be controlled during emergence and in the immediate postoperative period for many H&N procedures.

Extubation plan — Endotracheal extubation should be planned as thoroughly as endotracheal intubation, and requires an explicit strategy for patients who undergo H&N procedures.

Compared with other elective surgeries, H&N surgeries are associated with higher rates of complications during and immediately after emergence and planned extubation, including [128]:

●Laryngospasm

●Postextubation airway edema

●Postoperative airway obstruction

●Need for reintubation

One-third of adverse events reported to the NAP4 occurred during emergence and recovery from anesthesia [129]. (See 'Incidence of airway difficulty' above.)

An approach to extubation is outlined in extubation algorithms from the Difficult Airway Society in the United Kingdom (algorithm 2A-C) [130]. A strategy for extubation is also recommended in the ASA Practice Guidelines for Management of the Difficult Airway, and is consistent with our approach to extubation of patients who undergo H&N surgery (algorithm 1) [26].

The plan for extubation should be formulated with the surgeon and should consider the difficulty of initial intubation, the extent and duration of surgery, the potential for postoperative swelling or bleeding, and the patient's current and preoperative medical status.

Extubation may be delayed for patients who are predicted to be at high risk of failed extubation, and these patients should be transported to an intensive care unit (ICU) for further treatment. If a trial of extubation is considered for high-risk patients, all necessary equipment and personnel should be available for potential reintubation or establishment of a surgical airway. In this setting, we extubate over an airway exchange catheter.

Extubation of patients with a difficult airway and the use of the airway exchange catheter are discussed more fully separately. (See "Management of the difficult airway for general anesthesia in adults", section on 'Extubation'.)

Smooth extubation strategy — Extubation should occur when airway protective reflexes have returned, with the goal of preventing coughing and straining. The author's technique of choice is to replace the ETT with an SGA, where appropriate, and to facilitate emergence from anesthesia with low-dose remifentanil infusion. (See "Extubation following anesthesia".)

Strategies for smooth emergence and extubation include the following:

●The use of the SGA as a primary ventilatory device, in lieu of ETT. (See 'Supraglottic airways' above.)

●The Bailey maneuver – This technique provides airway support with an SGA (usually, an LMA) for emergence after removal of the ETT at a deep level of anesthesia [131]. The LMA is less stimulating to the airway and facilitates smooth emergence from anesthesia. For the Bailey maneuver, the LMA is placed behind the in-situ ETT, its cuff is inflated, the patient's airway is suctioned, and the ETT is removed. The ETT keeps the epiglottis out of the way of LMA insertion against the palatopharyngeal curve. The airway is then managed with the LMA until the patient awakens from anesthesia. (See "Extubation following anesthesia", section on 'Bailey maneuver'.)

●Remifentanil during emergence – Remifentanil infusion (eg, 0.03 to 0.08 mcg/kg/minute) can be continued during emergence from anesthesia to reduce cough and the hemodynamic changes associated with tracheal extubation [132]. Remifentanil provides a predictable, rapid, and almost simultaneous recovery of consciousness and protective airway reflexes.

●Antihypertensives – We prophylactically administer labetalol (0.1 to 0.3 mg/kg IV) at the end of surgery for hypertensive patients to avoid hypertension on emergence.

POSTOPERATIVE CARE — Many head and neck (H&N) procedures are performed on an ambulatory basis, and patients are discharged home after recovery from anesthesia. Multimodal strategies for postoperative pain control and postoperative nausea and vomiting (PONV) and postdischarge nausea and vomiting (PDNV) prophylaxis should be used for patient comfort and for fast-tracking ambulatory H&N surgical patients.

The disposition (ie, recovery room versus intensive care unit [ICU]) for patients who have had major H&N surgery should be determined by the need to delay extubation or monitor airway status, and medical concerns.

SUMMARY AND RECOMMENDATIONS

●Evaluation for difficult airway – Difficulty with airway management is significantly more common for patients who undergo head and neck (H&N) procedures than for many other surgical patients. Comprehensive preoperative airway evaluation should include assessment of predictors of difficult/impossible mask ventilation, their association with difficult direct laryngoscopy (DL), predictors of difficult videolaryngoscopy (VL), preoperative endoscopic airway evaluation (PEAE) findings, and the results of imaging studies (table 1 and table 3 and table 4). (See 'Airway evaluation' above.)

●Coordination with the surgeon – Anesthesia for H&N procedures requires close coordination with the surgeon, including airway management and extubation strategies, the need for a dry and still surgical field, and considerations for the use of neuromonitoring. (See 'Surgical considerations' above.)

●Airway management – The strategy for airway management should include a predetermined set of sequential plans for managing difficulty with or failure of the previous attempts. Airway management concerns that apply specifically to patients with H&N pathology include the following (see 'Airway management strategy' above):

•Difficulty with airway management should be expected for many H&N patients during induction and emergence from anesthesia.

•For anticipated difficult airway, advanced oxygenation techniques such as transnasal humidified rapid insufflation ventilatory exchange (THRIVE) should be strongly considered prior to and during induction of anesthesia and during intubation attempts. (See 'Oxygenation strategies' above.)

•VL should be strongly considered as the primary intubation technique for many of these patients. Repeated attempts at DL should be avoided, and limited to two. (See 'Laryngoscopy technique' above.)

•Inhalation induction has a high failure rate in patients with complex H&N pathology and should be considered in close cooperation with the surgeon. (See 'Intravenous versus inhalation induction' above.)

•Flexible scope intubation may fail in patients with H&N pathology because of difficulty in identifying the glottis, difficulty passing the scope or endotracheal tube (ETT), and bleeding. The combination of a flexible scope with a VL or optical stylet offers a wide view of the glottis and continuous visualization throughout intubation. (See 'Flexible scope intubation' above and 'Combined intubation techniques' above.)

•Rigid optical and video stylets may be used to bypass mobile supraglottic and glottic masses. (See 'Optical and video stylets' above.)

•Supraglottic airways (SGAs) can be used as primary ventilatory devices for selected patients who undergo H&N surgery, and may also be used for ventilation as a bridge to tracheal intubation. We suggest using a second-generation SGA for these patients (Grade 2C). (See 'Supraglottic airways' above.)

•If DL or VL fails, the surgeon may be able to intubate using the operative laryngoscope or rigid bronchoscope. (See 'Endotracheal intubation by the surgeon' above.)

•A tracheostomy may be the primary form of airway management and may be performed awake or after induction of anesthesia. (See 'Surgical airway' above.)

●General anesthesia – General anesthesia is the preferred technique for most H&N procedures. Monitored anesthesia care may be used for selected cases. (See 'Choice of anesthetic technique' above.)

•Our preferred technique for anesthesia for H&N procedures is total intravenous anesthesia (TIVA) with propofol and opioid infusions, with processed EEG monitoring. (See 'Choice of anesthetic agents' above.)

•We administer opioid infusions as an integral part of the anesthetic technique, with doses stratified according to the surgical stimulus, duration of surgery, and expected degree of postoperative pain. Opioid infusions facilitate controlled hypotension, suppress airway reflexes, minimize patient movement without the use of neuromuscular blocking agents (NMBAs), and facilitate smooth emergence from anesthesia (table 7). (See 'Opioids during maintenance of anesthesia' above.)

•We administer multimodal prophylaxis for postoperative nausea and vomiting (PONV) for all patients who undergo H&N procedures. (See 'Prophylaxis for postoperative nausea and vomiting' above.)

●Ventilation – Jet ventilation (JV) or apneic intermittent ventilation may be required for a variety of laryngologic procedures. THRIVE can be used effectively and successfully for selected patients undergoing laryngologic surgery. (See 'Ventilation' above.)

●Emergence and extubation – The goals for emergence from anesthesia should include a smooth awakening and extubation without coughing, straining, or retching, to avoid venous congestion and bleeding. When indicated, the plan for extubation should be formulated with the surgeon and should reflect the expected risk for postoperative airway complications. (See 'Extubation plan' above.)