TRACHEAL SURGERY IN COVID-19 PATIENTS — Tracheostomy may facilitate management of patients with novel coronavirus disease 2019 (COVID-19) who develop severe respiratory failure requiring prolonged mechanical ventilation [1]. A tracheostomy procedure (open or percutaneous) is an extremely high-risk procedure for infection of participating anesthesia, surgery, and other medical personnel due to aerosolization of oropharyngeal and tracheal secretions [2-5]. Although open surgical tracheostomy procedures are generally preferred, percutaneous procedures are not contraindicated [1,3,6]. (See "COVID-19: Management of the intubated adult", section on 'Tracheostomy'.)
Key principles for management of tracheostomy, bronchoscopic evaluation, or other tracheobronchial surgery in a COVID-19 patient include [1-5,7,8]:
●Multidisciplinary discussion that includes planning timing of the procedure, technical anesthetic and surgical details, minimizing risk by limiting number of staff and extent of exposure to aerosolized secretions, and management of anticoagulation (eg, stopping heparin infusions, ensuring platelet count >50,000/microL and international normalized ratio <1.5).
●Rigorous adherence to the use of properly applied personal protective equipment (PPE). (See "COVID-19: Perioperative risk assessment and anesthetic considerations, including airway management and infection control", section on 'PPE during airway management or aerosol generating procedures'.)
●Performing the procedure in a negative pressure operating room when feasible.
●Using disposable anesthetic and surgical equipment when feasible.
●Using deep neuromuscular blockade to avoid coughing.
●Minimizing the time that the airway is open to the environment, and allowing apnea before securing the airway, if tolerated, to reduce aerosolization of airway secretions. Some evidence suggests that open surgical tracheostomy has less risk for aerosolized spread of COVID-19 virus compared with percutaneous tracheostomy [3].
●Using a high efficiency particulate air (HEPA) filter somewhere in the anesthesia circuit, ideally, close to the patient.
●Inserting a tracheostomy tube that has a pre-connected HEPA filter.
●Avoiding disconnection of the HEPA filtered anesthesia circuit, whenever possible.
●Continuing lung-protective ventilation. (See "Mechanical ventilation during anesthesia in adults", section on 'Lung protective ventilation during anesthesia'.)
●Transporting the patient directly back to a dedicated COVID-19 intensive care unit.
Further details regarding anesthetic care of COVID-19 patients are available in a separate topic. (See "COVID-19: Perioperative risk assessment and anesthetic considerations, including airway management and infection control".)
INTRODUCTION — Elective or emergency tracheal surgical procedures are typically performed to improve tracheal patency or repair loss of tracheal integrity. Anesthetic challenges may include abnormal airway anatomy and physiology, requirements for specialized endotracheal tubes (ETTs) and additional airway devices to meet evolving intraoperative needs, and alternative modes of ventilation (eg, jet ventilation [JV], intermittent ventilation) if the trachea is open or obstructed.
This topic will discuss general considerations for anesthetic management of adult patients undergoing surgery in the tracheal region from the distal edge of the larynx to the tracheal bifurcation at the carina. Details regarding anesthetic management of specific tracheal surgical procedures are discussed in a separate topic. (See "Anesthesia for tracheal surgery: Specific procedures".)
Other topics discuss anesthetic management of patients undergoing surgical or other invasive procedures involving the larynx, bronchi, or esophagus:
●(See "Anesthesia for head and neck surgery".)
●(See "Anesthesia for adult bronchoscopy".)
●(See "Anesthesia for esophagectomy and other esophageal surgery".)
PREOPERATIVE ASSESSMENT AND PLANNING
Preanesthetic consultation — Tracheal lesions may cause airway obstruction [9]. The degree of airway patency may be dynamic and influenced by factors such as patient position, airway and thoracic muscle tone, mode of ventilation (spontaneous or controlled), or phase of respiration. A major goal of the preanesthetic evaluation is to determine whether the tracheal lesion could cause airway obstruction during induction of anesthesia, or subsequently during surgical manipulation and/or resection.
Preanesthetic assessment includes the medical history, physical examination, functional status, and review of imaging studies that define pathology (eg, radiographs, bronchoscopies) and flow-volume loops if available [9]. Details regarding evaluation of central airway obstruction are available in a separate topic. (See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults".)
●History – Determine what positions, breathing techniques, or other maneuvers improve or worsen breathing.
●Physical examination and functional status – Observe breathing at rest and, if possible, during mild exertion.
•Determine whether increased work of breathing and dyspnea on exertion are present in patients with tracheal stenosis. These symptoms reflect a 50 percent or greater reduction in luminal diameter [10,11].
•Auscultate for respiratory phase-specific noises that suggest location and degree of airway pathology. Inspiratory stridor is associated with at least a 50 percent reduction in diameter at the glottis or periglottis. Expiratory or biphasic stridor is associated with pathology below the vocal cords. Such findings suggest critically narrowed central airways with risk of acute airway obstruction during induction of general anesthesia due to collapse, secretions, or minor airway swelling.
•Observe the breathing pattern relative to posture. Patients choose their resting position to optimize tracheal patency. See if the patient can assume a supine posture without increasing breathing difficulty. Ideally, the induction position should be the patient's preferred posture.
•Perform a bedside version of the forced volume exhaled in the first second (FEV1), also known as a "birthday candle," test, to obtain a qualitative sense of the degree of dynamic respiratory function. Ask the patient to blow forcibly on your hand and look for airflow obstruction in this setting of high positive intrathoracic pressure during forced exhalation.
●Imaging studies – Radiographs and scans must be reviewed but may be falsely reassuring and often provide an incomplete picture. The patient's history and recent bronchoscopy results carry more weight. (See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults", section on 'Imaging'.)
●Flow-volume loops – If available, flow-volume loops may provide supplemental information regarding tracheal obstruction (figure 1 and figure 2 and figure 3) [12]. For example, blunted peak flows during inspiration suggest a fixed stenosis high in the trachea (or larynx). Reduced flow during expiration may occur with a fixed stenosis and/or dynamic tracheal collapse due to tracheomalacia in the lower trachea [13]. (See "Clinical presentation, diagnostic evaluation, and management of malignant central airway obstruction in adults", section on 'Pulmonary function tests'.)
Reevaluation on the day of surgery — Reevaluation on the day of surgery includes:
●Repeat a focused history and physical examination to check for interim changes since the preoperative assessment. Findings from recent examinations may underestimate the extent of pathology since some tracheal lesions have the potential for rapid progression that impacts patency.
●Confirm optimal condition for pulmonary and other medical comorbidities (in patients undergoing elective surgery).
For patients with changes in status, the surgical team is consulted to determine appropriate timing of elective surgery or the impact of new findings on management of an urgent or emergency surgical procedure.
Selection of anesthetic technique — The decision to offer topical anesthesia of the airway with optional sedation versus general anesthesia is based on the nature and goal of the procedure and patient status.
Use of local anesthetic for selected procedures — In some cases, part or all of the tracheal procedure can be accomplished by numbing the airway with topically applied local anesthetic or use of airway nerve blocks, with optional sedation when appropriate. Examples include (see "Anesthesia for tracheal surgery: Specific procedures"):
●Brief tracheal exam.
●Preprocedural flexible bronchoscopy when it is necessary to have an awake and cooperative patient so the surgeon can observe the dynamic nature of the pathology. (See "Anesthesia for adult bronchoscopy", section on 'Topical airway anesthesia with sedation'.)
●Placement of a silicone or expandable metal stent in selected patients. (See "Anesthesia for tracheal surgery: Specific procedures", section on 'Insertion of an endotracheal stent'.)
●Awake tracheostomy or dilator cricothyroidotomy for patients with a critically compromised airway or for a hemodynamically unstable patient. Such cases are typically performed with local anesthesia and likely no sedation. (See "Anesthesia for tracheal surgery: Specific procedures", section on 'Percutaneous "mini" tracheostomy' and "Tracheostomy in adults: Techniques and intraoperative complications", section on 'Selecting percutaneous versus operative'.)
General anesthesia — General anesthesia is the most commonly used anesthetic for most major tracheal surgical procedures (eg, tracheal resection or reconstruction) and is required for repair of tracheoesophageal fistula or tracheal reconstruction. (See "Anesthesia for tracheal surgery: Specific procedures".)
Planning for postoperative analgesia — For minor closed tracheal procedures, administration of postoperative pain medication is typically unnecessary since most patients awaken with no pain and may be detrimental since airway patency may be tenuous. After a transverse open cervical incision, postoperative pain is usually minimal and easily treated with multimodal nonopioid systemic analgesic agents, while long-acting opioids are avoided. (See 'Postoperative management' below.)
If a thoracotomy is required to accomplish the tracheal surgical procedure, either thoracic epidural analgesia (TEA) or a paravertebral block (PVB) is typically employed to provide postoperative analgesia, similar to pain management after any thoracotomy. Placement of the TEA or PVB catheter often occurs in the preoperative period. Alternative analgesic techniques are offered if neither TEA nor PVB is appropriate, or if attempted preoperative placement of a TEA or PVB catheter is unsuccessful. These techniques are discussed separately. (See "Anesthesia for open pulmonary resection", section on 'Planning for postoperative analgesia' and "Anesthesia for open pulmonary resection", section on 'Post-thoracotomy pain management'.)
Preoperative team planning
General considerations — Preoperative communication with the surgery team and joint planning are necessary to avoid or immediately manage loss of airway patency or inability to ventilate and oxygenate the patient during induction, emergence, or critical portions of the procedure [14], as well as to manage the potential for airway fire. (See 'Management of general anesthesia' below and "Fire safety in the operating room", section on 'Fire in the airway'.)
Preoperative planning is particularly important when the airway and surgical field will be shared or requires close proximity between anesthesiologists and surgeons. The anesthesiologist must also understand the proposed surgical procedure since inability to ventilate may occur due to:
●Airway obstruction due to tracheal manipulation or compression of airway structures
●Loss of airway continuity or patency during planned tracheal resection or unplanned tracheal injury
●Planned steps in the procedure that temporarily obstruct the airway (eg, tracheal dilation, stent placement)
Specific communication protocols have been developed for management of a difficult airway including use of jet ventilation (JV) if necessary [14]. While checklists are important, they do not supplant the absolute need for pre-procedure education and training regarding unusual management approaches or less commonly used devices. Anesthesia providers should become skilled with the use, dangers, and methods for troubleshooting problems associated with JV and other nonstandard ventilation strategies before starting an elective tracheal surgical procedure.
●Preoperative briefing – The preoperative briefing is typically performed with the aid of a checklist. (See "Safety in the operating room", section on 'Briefings' and "Safety in the operating room", section on 'Checklists'.)
●Intraoperative timeouts – A timeout just before incision is necessary, and additional intraoperative timeouts are useful in selected tracheal procedures to ensure adequate communication as surgery progresses. (See "Safety in the operating room", section on 'Timeouts'.)
●A pre-emergence timeout is essential. Surgeons must communicate regarding procedural details that may cause postoperative problems, particularly factors that may interfere with ventilation or put the surgical repair at risk. (See 'Emergence and extubation' below.)
Key points for surgical briefings — The following specific points are addressed during these briefings and timeouts [14]:
●Discussion of potential intraoperative need for modifications of the surgical plan and goals, aligned with dynamic management and sequential changes of airway devices and ventilation modes.
●Establishment of rescue plans if inability to ventilate occurs during induction or emergence from anesthesia, or due to intraoperative surgical interventions or complications. All equipment that may be necessary should be immediately available before starting the procedure [15].
●Discussion and classification of fire risk (eg, the "Silverstein Fire Risk Assessment Tool," which assigns risk points [0 to 3]) based on the selected ignition source and its proximity to potential oxidizers (oxygen or nitrous oxide) and flammable tissue or material. Tracheal procedures have the highest airway fire risk score (ie, 3 points). (See "Fire safety in the operating room", section on 'Risk-based approach to fire prevention' and "Fire safety in the operating room", section on 'Risk prevention: High-risk procedures'.)
Precautions that mitigate airway fire risk are discussed, as outlined in the American Society of Anesthesiologists (ASA) practice advisory for the prevention and management of operating room fires (algorithm 1) [16]. These include (see "Fire safety in the operating room", section on 'Special precautions during airway surgery' and "Fire safety in the operating room", section on 'Fire in the airway'):
•Discussion of ignition source choice and management plans. Compared with other electrosurgery units, lasers (collimated, in-phase high-energy beams that travel unattenuated through space) have a particularly high risk for inappropriate energy transfer to tissue, which may cause injury or fire [17]. (See "Basic principles of medical lasers", section on 'Laser principles'.)
•Designation of a laser safety officer with an explicit role of safety oversight to ensure use of a reduced fraction of inspired oxygen (FiO2), proper eyewear, laser-resistant endotracheal tubes (ETTs), proper plume management, and other safety measures. (See "Fire safety in the operating room", section on 'Causes: The fire triad'.)
●Discussion of potential adverse or beneficial changes in tracheal anatomy. The trachea is a dynamic and mobile structure that may change during ventilation or surgical interventions. Examples include:
•Length changes – The average tracheal length is 11.25 cm, and average external diameter is 20 mm for males (inner diameter [ID] 15 to 25 mm) and 15 mm for females (ID 10 to 21 mm).
-Approximately 3 cm caudal excursion of the carina occurs with deep inspiration. This excursion may be observed as tracheal, "tugging," when the elastic limits of elongation are reached, with additional downward pull during strained inspiratory efforts. After a tracheal repair with a fragile suture line, strained inspiratory efforts with resultant added tracheal tension should be avoided.
-Head or neck extension places cephalad pull on the trachea and can alter the length by a few centimeters, while flexion reduces tension on the trachea and pushes the extrathoracic trachea down into the mediastinum. This mobility may be used to facilitate optimal surgical exposure of the trachea or to reduce tension on suture lines if necessary.
-In some cases, up to 50 percent of tracheal length is surgically resected. A laryngeal or hilar release may add 2 to 3 cm of additional tracheal length and mobility, thereby reducing tension on anastomotic sites [18].
•Diameter changes – Diameter changes occur as a result of intrathoracic pressure changes. Positive intrathoracic pressure causes inward projection of the membranous back wall of the trachea, while negative pressure causes an outward bowing of the back wall. The cartilaginous portion of the trachea is better structured and so is not as significantly altered by pressure changes [19].
-Tidal volume inhalation causes a 10 percent diameter increase.
-Forced exhalation and coughing result in a 30 percent diameter decrease.
-If tracheomalacia is present, high positive intrathoracic pressure (eg, during forced exhalation or coughing) may cause complete tracheal obstruction. However, reopening will likely occur with spontaneous inhalation or applied positive pressure ventilation.
ANESTHETIC MANAGEMENT: GENERAL CONSIDERATIONS
Operating room setup — Preparations for laryngeal or tracheal surgery include ensuring availability and proper function of all equipment that may be necessary during induction of anesthesia and subsequent surgical interventions. Depending on the planned procedure, such equipment may include specialized endotracheal tubes (ETTs), supraglottic airway devices (ie, laryngeal mask airway [LMA]), airway exchange catheters, bronchial blockers, tracheal tubes or stents, flexible and/or rigid bronchoscopy equipment, or a jet ventilator setup [9,14,20-22]. Other checks of light sources, endoscopic tower functionality, and subjective confirmation of delivered jet ventilation (JV) pressure are completed before beginning the procedure [14].
Endotracheal tube selection — An array of ETTs may be necessary during induction of anesthesia and subsequent surgical interventions [20,21]. These needs should be anticipated to ensure immediate availability of such equipment. (See 'Preoperative team planning' above and 'Induction and airway management' below.)
ETTs are available in a variety of sizes (diameter and length), material (metal or plastic), and construction (armored, laser-resistant, tube tip shape, single versus double-lumen). Also, ETTs are manufactured with variations in cuff volume, configuration, and location of the cuff endpoint relative to the tip of the ETT. Goals for selection of an appropriate ETT for a planned tracheal procedure include protection of the airway, reliable gas exchange, and provision of optimal surgical exposure.
Specific considerations include:
●If laser use in or near the airway is planned, we select a laser-resistant ETT or JV catheter [16]. (See "Fire safety in the operating room", section on 'Fire in the airway' and "Fire safety in the operating room", section on 'Special precautions during airway surgery'.)
We prefer a laser-resistant plastic catheter with a, "cage," that helps to stabilize the catheter within the trachea when JV is used (picture 1). If a rigid bronchoscope is used, we attach the JV tubing to a purpose-built port with a Luer-Lok connection on the bronchoscope (picture 2). (See "Anesthesia for adult bronchoscopy", section on 'Jet ventilation'.)
●If a highly flexible crush-resistant tube is necessary to prevent kinking (eg, when the tube may be sharply bent after insertion into a tracheostomy stoma), we select a wire-reinforced, "armored," ETT (picture 3).
●If a long ETT is needed to allow cuff placement distal to the tracheal pathology (eg, during repair of a distal tracheoesophageal fistula), mainstem bronchial intubation might be necessary. Options to consider include (see "Anesthesia for tracheal surgery: Specific procedures", section on 'Induction and initial airway management' and "Lung isolation techniques") [23]:
•A double-lumen ETT (DLT) with only the endobronchial cuff inflated after it has been advanced into the mainstem bronchus on the side of the lung that will be ventilated. In addition, an optional bronchial blocker can be passed into the bronchial lumen of the nonventilated lung to isolate it and prevent soiling via the fistula.
•If a DLT is too bulky, then an extra-long ETT may be advanced into the mainstem bronchus of the lung that will be ventilated. However, some long ETTs are floppy with a tendency to dislodge from an endobronchial position (picture 4). As mentioned, an optional bronchial blocker can be passed into the bronchial lumen of the lung that will not be ventilated to isolate it and prevent fistula soiling.
•Other ways to create a long ETT with a small diameter and improved stability include:
-Cutting the tracheal channel and its cuff off from a DLT, and using only the endobronchial side of the DLT with its preserved cuff. However, this requires preparation time that includes careful and thorough sanding/smoothing of the cut edges, and it is difficult to cut off the tracheal lumen (picture 4).
-Combining two regular ETTs. The larger of the two is used distally, with a preserved cuff and pilot balloon. The smaller ETT is used as an extension within the larger one. The two ETTs are joined together after wiping the connecting surfaces with alcohol to improve bonding (picture 4).
Careful maintenance of the integrity of the ETT cuff and pilot balloon is essential during use of these improvised long ETT alternatives. Integrity is reconfirmed just prior to use.
•Also, consider management of the opposite/unintubated mainstem bronchus after planned mainstem bronchial intubation. A bronchial blocker may be selected to protect the contralateral lung, or a JV catheter may be selected to ventilate the contralateral lung.
Supraglottic airway devices — Some centers employ an LMA as the primary airway device for selected patients undergoing laryngotracheal surgery [9,20,22]. An advantage of this technique is the absence of airway tubing in the surgical field, thereby allowing continuous visualization of the posterior trachea during anastomosis [9,24]. Also, avoidance of airway catheters or tubes near a friable tracheal lesion may prevent tracheal injury. (See "Supraglottic devices (including laryngeal mask airways) for airway management for anesthesia in adults".)
Monitoring — Standard American Society of Anesthesiologists (ASA) monitors are always employed (table 1).
Also, we typically use processed or unprocessed electroencephalography (EEG), and are careful to avoid high EEG indices that may indicate possible awareness (see "Accidental awareness during general anesthesia", section on 'Brain monitoring'). Such neuromonitoring is particularly important if a total intravenous anesthesia (TIVA) technique is planned to maintain anesthesia in a patient with a peripheral intravenous (IV) catheter that cannot be seen after positioning the surgical drapes, and/or if administration of a neuromuscular blocking agent (NMBA) is planned. These considerations are discussed in detail separately. (See "Accidental awareness during general anesthesia", section on 'Total intravenous anesthesia' and "Accidental awareness during general anesthesia", section on 'Neuromuscular blockade'.)
We insert an intra-arterial catheter in selected patients, but not if the planned tracheal procedure will be minor or of brief duration. An intra-arterial catheter is useful for (see "Intra-arterial catheterization for invasive monitoring: Indications, insertion techniques, and interpretation"):
●Continuous monitoring of arterial blood pressure, so that hemodynamic instability due to hypoxia, hypercarbia, high airway pressures, hemorrhage, or compression of the heart or major vessels will be immediately detected, particularly during intrathoracic procedures or when changes in airway device or mode of ventilation will be necessary. (See 'Options for intraoperative oxygenation and ventilation' below.)
●Intermittent sampling of arterial blood gases for direct measurement of partial pressure of oxygen (PaO2) and partial pressure of carbon dioxide (PaCO2) to assess adequacy of oxygenation and ventilation during the perioperative period. Direct measurement is particularly useful during procedures requiring one lung ventilation (OLV) or JV.
Options for intraoperative oxygenation and ventilation — Choice of intraoperative ventilation technique depends on preexisting upper airway and tracheal anatomy, pulmonary pathology, and the anticipated surgical interventions, particularly whether the trachea will be opened or will remain intact [9,15].
Standard positive pressure ventilation — If the trachea will remain intact distal to the tip of the ETT, then we use standard volume- or pressure-controlled positive pressure ventilation (PPV) via a cuffed ETT or, in some cases, an uncuffed ETT that is gently wedged (ie, "press-fit") against the tracheal wall. (See "Mechanical ventilation during anesthesia in adults".)
Jet ventilation — JV is typically used if the airway will be open with only loose coupling to the ventilation system, or if surgical exposure and technical conditions would be facilitated by a small ventilation catheter and/or a quieter surgical field than standard ventilation affords (due to minimal chest excursions with small JV tidal volumes) [9]. Also, JV might be useful to augment standard PPV by providing independent oxygenation of targeted lobes or distal airway segments (eg, during tracheoesophageal fistula repair or tracheal reconstruction involving the distal trachea or carina). (See "Anesthesia for tracheal surgery: Specific procedures", section on 'Open repair or stent occlusion of a tracheoesophageal fistula' and "Anesthesia for tracheal surgery: Specific procedures", section on 'Tracheal resection and reconstruction'.)
Typically, a total intravenous anesthesia (TIVA) technique is employed to ensure a constant level of anesthesia when JV is used in the absence of standard PPV, since the anesthesia machine is not connected to the patient. Also, a neuromuscular blocking agent (NMBA) is often administered to induce complete muscle relaxation. During general anesthesia with these techniques, precautions are taken to avoid awareness with recall. (See "Anesthesia for adult bronchoscopy", section on 'Total intravenous anesthesia' and "Accidental awareness during general anesthesia".)
Management of JV is as follows:
●Jet ventilator settings – JV employs a low-volume, relatively high-pressure bolus of gas delivered through a metal or plastic catheter. The point of gas delivery may be either supra- or infraglottic. Under direct guidance in open procedures (or aided by a bronchoscopic visualization during closed procedures), a small-diameter flexible JV catheter can be adjusted in the surgical field (picture 5). We usually initiate JV using a fraction of inspired oxygen content (FiO2) of 1.0 and a low frequency respiratory rate of 15 breaths per minute with a driving pressure of 15 pounds per square inch. That driving pressure is likely to be a safe starting point but may need to be adjusted upward immediately until there is some visible chest rise. The frequency may be increased but must always allow for full chest recoil and exhalation prior to the start of the sequential breath (ie, each delivered breath may be right on the tail end of exhalation but should never overlap). In the presence of chronic obstructive pulmonary disease, reaching full end-expiration may be challenging.
Subsequently, the FiO2 is adjusted as needed to maintain adequate oxygenation. As always, if ignition sources are to be used near an open airway, an oxygen analyzer must be used to ensure that the fraction of expired oxygen content (FeO2) is <0.3. In addition, some well-timed PPV breaths through the ETT or LMA may be required.
During JV, care must be taken to ensure effective ventilation, while avoiding hypothermia, desiccation of airway tissue, or catastrophic injury such as barotrauma or pneumothorax. We use the only electronic JV system that is commercially available in the United States (the Monsoon III Jet Ventilator (picture 6)). This ventilator humidifies the gas and has sampling catheters that measure airway pressures within the JV catheter. To prevent pneumothorax, pressures exceeding the chosen limit cause an automatic suspension of ventilation that resumes when the pressure issue is resolved. Despite these precautions, not all patients will tolerate JV if their lung function and habitus are not favorable. (See "High-frequency ventilation in adults", section on 'Harms'.)
●Jet ventilation via a rigid bronchoscope – In some cases, JV is employed via a rigid bronchoscope. Some rigid bronchoscopes have a purpose-built port with a Luer-Lock connection for the JV tubing (picture 2). Typical settings for JV use in adults during rigid bronchoscopy, suspension microlaryngoscopy, or emergency JV via a catheter inserted through the cricothyroid membrane are discussed in a separate topic. (See "Anesthesia for tracheal surgery: Specific procedures", section on 'Rigid bronchoscopy' and "Anesthesia for adult bronchoscopy", section on 'Jet ventilation'.)
Intermittent ventilation — A completely unobstructed surgical field may be achieved by intermittent removal of the airway device (ETT or JV catheter) from the trachea during limited periods of apnea. Preoxygenation is employed before each apneic episode to prolong the duration of the apneic period before clinically significant desaturation occurs [25]. This duration varies according to patient- and procedure-related factors (figure 4) [26]. (See "Rapid sequence intubation for adults outside the operating room", section on 'Preoxygenation'.)
Potential risks of intermittent ventilation with periods of apnea include worsening of hypoxemia, hypercapnia, and acidosis with consequent increasing pulmonary vascular resistance and exacerbation of right heart dysfunction. Increased heart rate, blood pressure, and cardiac arrhythmias may also occur. (See "Permissive hypercapnia during mechanical ventilation in adults", section on 'Adverse effects'.)
Typically, a TIVA technique is employed during intermittent apnea to ensure a constant level of anesthesia.
Spontaneous ventilation — The author strongly prefers using controlled ventilation (either PPV or JV) via an appropriately sized and carefully positioned ETT or LMA, typically with deep neuromuscular blockade for elective tracheal and carinal resection procedures. However, some centers employ spontaneous ventilation for selected laryngotracheal surgical cases, with use of either an LMA or no airway device [9,20]. With spontaneous ventilation, intravenous anesthetic agents must be carefully titrated to preserve ventilatory drive. When feasible, neuraxial or regional anesthesia may be used to aid in maintaining patient comfort, minimizing movement and coughing, and facilitating a lighter level of general anesthesia [9].
Advantages of employing spontaneous ventilation with an LMA (or no airway device) include avoidance of airway catheters or devices near a tracheal lesion, thereby allowing unhindered surgical visualization during the procedure (see 'Supraglottic airway devices' above). Also, the absence of any intratracheal airway catheters or device may decrease the risk of coughing and traumatic rupture of a tracheal anastomosis during emergence from general anesthesia (see 'Emergence and extubation' below). Furthermore, spontaneous ventilation of both lungs is possible during carinal procedures [9].
Disadvantages of employing spontaneous (negative pressure) ventilation include the possibility of inadequate ventilation and risk of aspiration (particularly during attempted “rescue” conversion to positive pressure ventilation) [9]. Furthermore, it is not possible to achieve lung isolation or perform an anastomotic leak test by using a brief Valsalva maneuver (eg, after tracheal reconstruction). In addition, although rare, a patient with an extrathoracic lesion may develop airway obstruction during spontaneous ventilation due to negative intratracheal pressure [27].
Extracorporeal membrane oxygenation — Extracorporeal membrane oxygenation (ECMO) involves gas exchange (oxygen [O2] and carbon dioxide [CO2]) across an artificial membrane into an oxygenation circuit, without use of a pump. Elective or emergency venovenous (VV) or venoarterial (VA) ECMO is occasionally employed for selected patients at high risk for inadequate gas exchange (eg, unusual location or size of a tracheal lesion or anterior mediastinal mass) [9,14,15,20,21,28-31]. ECMO is highly effective for maintenance of adequate oxygenation and ventilation in the absence of a patent airway. Another advantage is the absence of airway devices or catheters in the surgical field, thereby providing a clear view of the posterior trachea during anastomosis [9]. Notably, since either VV ECMO or VA ECMO requires anticoagulation (partial heparinization), risk of surgical bleeding is increased. (See "Extracorporeal membrane oxygenation (ECMO) in adults" and "Anesthesia for patients with an anterior mediastinal mass", section on 'Planned cardiopulmonary bypass'.)
MANAGEMENT OF GENERAL ANESTHESIA
Induction and airway management — Choice of induction technique for general anesthesia is based on surgical requirements and potential for compromised ventilation [9]. Critical decisions include timing of endotracheal intubation (preinduction [awake] versus postinduction [asleep]), selection of an intravenous (IV) versus an inhalation induction technique, whether to use a neuromuscular blocking agent (NMBA), and timing for initiation of positive pressure ventilation (PPV). These decisions are based on knowledge gleaned during preoperative assessment of the patient and consultation with the surgeon. (See 'Preoperative assessment and planning' above.)
As the ventilation mode shifts from spontaneous negative pressure breathing to applied PPV during induction of anesthesia, the presence of a tracheal or extrinsic mass may result in airway collapse and inability to achieve adequate mask ventilation. Administration of a NMBA may not improve (or may actually worsen) the clinician's ability to ventilate the patient.
Thus, careful preparation and particular caution is necessary before inducing general anesthesia in a patient with tracheal pathology. The entire surgical, anesthesia, and nursing teams should be assembled, attentive, and ready to help execute plans discussed in the preoperative briefing. (See 'Key points for surgical briefings' above.)
General concepts for the induction sequence include [9]:
●If there are no risks for airway collapse or compromise during induction (eg, recent uneventful routine induction with no interval changes in physical status, tracheal pathology that does not result in a critically compromised airway), then an IV anesthetic induction technique may be selected. In this setting, we typically use a standard IV induction with propofol 2 mg/kg and fentanyl 150 to 250 mcg, plus an NMBA. Administration of an NMBA is withheld until the ability to provide adequate PPV is ensured. IV induction is also reasonable in a patient with tracheomalacia if positive pressure mask ventilation is likely to improve tracheal patency. (See "Induction of general anesthesia: Overview" and "General anesthesia: Intravenous induction agents".)
●If adequate oxygenation and ventilation during induction is thought to depend on maintenance of spontaneous negative pressure breathing so that respiratory mechanics remain similar to the awake state (eg, critical tracheal stenosis, dynamic pathology such as combined stenosis and malacia or an unstable tracheal mass), then an inhalation induction with sevoflurane is selected [27]. (See "Induction of general anesthesia: Overview", section on 'Inhalation anesthetic induction'.)
An inhalation induction technique should be considered only after consultation with the surgeon to ensure adequate preparation for urgent intervention (eg, rigid bronchoscopy) should this become necessary due to airway compromise [32]. (See "Anesthesia for adult bronchoscopy", section on 'General anesthesia for rigid bronchoscopy' and "Anesthesia for head and neck surgery", section on 'Surgical airway'.)
We employ the following specific techniques during an inhalation induction in patients with tracheal pathology:
•Minimize or avoid preinduction sedation to preserve respiratory drive.
•Adjust the head of the bed to a 30 degree inclination (to optimize functional residual capacity [FRC] and improve respiratory mechanics), or allow the awake patient to choose their own best position for spontaneous ventilation. (See 'Preanesthetic consultation' above.)
•Preoxygenate [25]. (See "Management of the difficult airway for general anesthesia in adults", section on 'Patient preparation'.)
•In selected cases (eg, critical tracheal stenosis), inhaled heliox may be employed to decrease resistance to airway flow. Heliox is a mixture of oxygen and helium that generates less airway resistance than pure oxygen due to its decreased gas density, thereby allowing more efficient work of breathing. (See "Physiology and clinical use of heliox".)
•Initiate inhalation anesthesia with a low concentration of sevoflurane and then slowly increase the concentration. Notably, adults may hold their breath if a high concentration of sevoflurane is administered in the first breath, resulting in loss of airway control. Use particular caution in the setting of tracheal stenosis since inhalation induction of general anesthesia may require several minutes. During this time, there is increased risk of breath-holding, coughing, or vomiting because of a protracted stage 2 (table 2).
•During any inhalation induction, we ensure that room noise and distractions are minimized, while the inhalation anesthetic level is deepened as quickly as possible.
•Once an anesthetized breathing pattern is established (rapid, regular, decreased tidal volumes (figure 5)), we apply a low level of positive pressure near the end of each spontaneous inhaled breath to test the airway for patency, then gradually apply positive pressure at an increasingly earlier point during inhalation.
•If PPV is feasible and ventilation can be fully controlled, we complete anesthetic induction with IV induction agents and an NMBA (if desired).
●If there is significant risk that the anesthesiologist will be unable to secure the airway and initiate PPV after induction of general anesthesia, then an awake intubation technique is employed to maintain the patient's compensated functional physiology and respiratory mechanics during intubation.
We employ the following specific techniques during an awake intubation in patients with tracheal pathology:
•Communicate with the patient. We use only mild and carefully controlled sedation. Thorough topical airway anesthesia with local anesthetic is necessary, as described separately. (See "Anesthesia for adult bronchoscopy", section on 'Topical anesthesia'.)
•Ensure that the surgeon is present and immediately available for insertion of a previously set-up small diameter rigid bronchoscope. Effective PPV via a rigid bronchoscope is likely to be adequate, but the anesthesiologist must be prepared to initiate jet ventilation (JV) before or immediately after its insertion. (See "Anesthesia for adult bronchoscopy", section on 'General anesthesia for rigid bronchoscopy'.)
●Administration of an NMBA is withheld until the ability to provide adequate ventilation (via either PPV or JV) is ensured.
●In patients with tracheoesophageal fistula, it is important to avoid PPV until the fistula has been isolated by an endotracheal tube (ETT) properly positioned distal to the fistula, thereby preventing gastric insufflation and pressurization. If the defect is distally located in the trachea, a long ETT may be needed (picture 4). If the pathology location and the ETT choice require a mainstem intubation, then a bronchial blocker may be needed to prevent soilage of the non-ventilated lung. Once the fistula is isolated and the airway is protected, normal pressure settings are used as PPV is initiated. (See "Anesthesia for tracheal surgery: Specific procedures", section on 'Open repair or stent occlusion of a tracheoesophageal fistula'.)
●A planned preinduction tracheostomy or emergency cricothyroidotomy may be necessary in rare cases. However, a tracheostomy will not reestablish airway patency if the tracheal pathology causing airway obstruction is distal to the end of the tracheostomy tube. In such cases, an ETT, ideally wire-reinforced with a small diameter, as well as a JV catheter, should be immediately available for insertion via the tracheostomy stoma. (See 'Jet ventilation' above.)
●A laryngeal mask airway (LMA) may be employed for selected patients until cross-table ventilation can be established [9,20,22,33]. Or, the cross-table ventilation may not be necessary if the transected trachea is traversed only by a small JV catheter passed through the LMA (picture 5). (See 'Supraglottic airway devices' above and "Supraglottic devices (including laryngeal mask airways) for airway management for anesthesia in adults".)
●Rarely, extracorporeal membrane oxygenation (ECMO) may be necessary [14,15,20,21,28-31]. Advance planning is critical if ECMO is likely to be needed. (See 'Extracorporeal membrane oxygenation' above and "Extracorporeal membrane oxygenation (ECMO) in adults".)
Maintenance — The decision to use total intravenous anesthesia (TIVA) or an inhalation anesthetic technique is based on several procedure-specific factors including duration. (See "Maintenance of general anesthesia: Overview", section on 'Total intravenous anesthesia' and "Maintenance of general anesthesia: Overview", section on 'Inhalation anesthetic agents and techniques'.)
Typically, a TIVA technique is selected for periods of the procedure that involve unreliable delivery and unreliable end-tidal measurements of inhaled anesthetic gases (eg, during JV, intermittent ventilation, or frequent suctioning of the airway), or if there will be significant potential for leakage of inhaled anesthetic gas after the airway is opened by a tracheal incision [9,21,34].
An NMBA is usually necessary to facilitate portions of a tracheal procedure. However, agent selection and timing of administration are challenging because dense muscle relaxation must be followed by reliable rapid recovery. For example, brief periods of intense stimulation occur during laser surgery of the trachea or insertion of a rigid bronchoscope. In these cases, the duration of the surgical procedure may be brief and the time between end of procedure and ready to emerge may be very short. For cases expected to last <20 minutes, we used to typically select a succinylcholine infusion, with care to avoid phase 2 blockade (see "Clinical use of neuromuscular blocking agents in anesthesia", section on 'Pharmacology of succinylcholine'). Now, with sugammadex on formulary, we use rocuronium for all cases, long and short (see "Clinical use of neuromuscular blocking agents in anesthesia", section on 'Rocuronium'). If rapid reversal of a relatively large dose of rocuronium is necessary when unexpected or abrupt termination of a surgical procedure occurs, then sugammadex may be administered in doses up to 16 mg/kg [35,36]. (See "Clinical use of neuromuscular blocking agents in anesthesia", section on 'Sugammadex'.)
Although manipulation of the trachea is exceedingly stimulating, there is little postoperative pain. Thus, we do not administer intraoperative long-acting opioids for tracheal procedures that do not require a thoracotomy. (See 'Pain management' below.)
Emergence and extubation — After any tracheal procedure, a final timeout for communication between the surgeon and anesthesiologist is important to establish an airway support plan for the immediate postextubation period (see 'Preoperative team planning' above). Problems may occur due to presence of excessive secretions or blood in the airway, vocal cord swelling noted after proximal tracheal manipulation or rigid bronchoscopy that necessitates pre-emergence administration of dexamethasone 8 to 10 mg to reduce swelling, or anticipated complications due to an ill-fitting stent. Also, the immediate postoperative ventilation support plan is planned during this final timeout. This may include use of continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP), establishment of positive pressure limits, criteria for endotracheal reintubation (and whether the anesthesiologist or the surgeon will attempt reintubation), or tracheostomy if necessary.
At the end of the procedure, the surgeon may plan to perform a final flexible bronchoscopic examination for tracheal evaluation or to clear secretions from the airway. If so, options include bronchoscopy through the ETT or extubation of the anesthetized patient with immediate placement of an LMA to facilitate this final bronchoscopy. (See "Supraglottic devices (including laryngeal mask airways) for airway management for anesthesia in adults" and "Anesthesia for open pulmonary resection", section on 'Final bronchoscopy before emergence'.)
Prerequisites for extubation include a thorough suctioning of the oropharynx, full return of neuromuscular function after reversal of the NMBA, optimal respiratory mechanics and adequate spontaneous tidal volumes and respiratory rate. Also, the patient must be conscious with the ability to protect the airway after extubation. Supplemental oxygen is administered before and after extubation to maintain adequate oxygenation. (See "Emergence from general anesthesia", section on 'Preparations for emergence'.)
The anesthesiologist continues close observation of airway patency during and immediately after emergence and extubation. Clear and interactive communication with the patient is essential, including ongoing reassurance. The surgeon should remain immediately available and the operating room team should keep equipment such as rigid bronchoscopes in the operating room for patients with a potentially tenuous airway.
Prompt intervention is necessary if there are symptoms or signs of respiratory distress. Development of airway obstruction is more likely in a patient who had intraoperative airway bleeding or excessive secretions since even a small clot or mucous plug may compromise a narrowed airway. Notably, in patients with a tracheal stent, any drift in stent placement may result in acute malposition causing airway occlusion (see "Anesthesia for tracheal surgery: Specific procedures", section on 'Insertion of an endotracheal stent'). In some cases, the possibility of vocal cord edema or recurrent laryngeal nerve dysfunction should be ruled out by checking phonation and/or inspection with flexible bronchoscopy. (See "Respiratory problems in the post-anesthesia care unit (PACU)", section on 'Vocal cord paralysis'.)
POSTOPERATIVE MANAGEMENT
Pain management — After a closed tracheal procedure, pain medication is typically unnecessary.
After a transverse cervical incision, postoperative pain is usually minimal. Typical options include a multimodal nonopioid systemic analgesic regimen with acetaminophen or a nonsteroidal antiinflammatory agent (NSAID) [9]. Gabapentin may be administered, but evidence of a beneficial effect is lacking [37]. If necessary for complaints of pain in the immediate postoperative period, intravenous (IV) ketorolac (eg, 15 to 30 mg) may be administered together with small doses of IV fentanyl (eg, 25 to 50 mcg). IV acetaminophen may also be used, if acetaminophen was not administered in the preoperative period. (See "Management of acute perioperative pain in adults".)
After major tracheal surgical procedures that required a thoracotomy, postoperative pain management is similar to that for patients undergoing open pulmonary resection. Thoracic epidural analgesia (TEA) or paravertebral block (PVB) analgesia are effective techniques that are used when feasible. Planning for these techniques and, often, placement of the TEA or PVB catheter occurs in the preoperative period. Alternative analgesic techniques are offered if neither TEA nor PVB is appropriate, able to be placed. These techniques are discussed separately. (See 'Planning for postoperative analgesia' above and "Anesthesia for open pulmonary resection", section on 'Post-thoracotomy pain management'.)
Long-acting opioid agents are avoided, since airway patency may be tenuous after tracheal surgery.
Transfer to intensive care unit — Patients undergoing tracheal resection or reconstruction, repair of tracheoesophageal fistula, or other high-risk tracheal surgical procedures are transported while monitored to an intensive care unit (ICU) for postoperative observation and further management [9]. (See "Anesthesia for tracheal surgery: Specific procedures", section on 'Tracheal resection and reconstruction' and "Anesthesia for tracheal surgery: Specific procedures", section on 'Open repair or stent occlusion of a tracheoesophageal fistula'.)
A standard postoperative handoff procedure is employed in the ICU or post-anesthetic care unit (PACU) . The following specific points are also addressed:
●Positive pressure limits for patients who require airway support (eg, bilateral positive airway pressure [BiPAP])
●Pulmonary toilet safety considerations (eg, length-limited blind tracheal suctioning, criteria for performing fiberoptic bronchoscopy to clean the airway)
●Criteria for reintubation or tracheostomy
●Plans for pain management, including the need to avoid long-acting opioids
SUMMARY AND RECOMMENDATIONS
●Tracheostomy may facilitate management of patients with novel coronavirus disease 2019 (COVID-19) who develop severe respiratory failure requiring prolonged mechanical ventilation. Key principles for management of tracheostomy, bronchoscopic evaluation, or other tracheobronchial surgery in a COVID-19 patient have been developed. (See 'Tracheal surgery in COVID-19 patients' above.)
●A major goal of the preanesthetic evaluation is to determine whether the tracheal lesion could cause airway obstruction during induction of anesthesia, or later during surgical manipulation and/or resection. Airway patency may be dynamic and influenced by factors such as patient position, tone of chest and airway muscles, mode of ventilation (spontaneous or controlled), or phase of respiration. Reevaluation is necessary on the day of surgery. (See 'Preanesthetic consultation' above and 'Reevaluation on the day of surgery' above.)
●Most patients undergoing tracheal surgery require general anesthesia. In selected cases (eg, tracheostomy, preprocedure flexible bronchoscopy, placement of a silicone or expandable metal stent), topically applied local anesthetic or use of airway nerve blocks plus optional sedation may be employed. (See 'Selection of anesthetic technique' above.)
●Preoperative communication with the surgery team with joint planning is necessary to avoid the possibility of airway fire, and to avoid or immediately treat loss of airway patency or inadequate ventilation and oxygenation during induction, emergence, or during surgical interventions. (See 'Preoperative team planning' above.)
●An array of specialized endotracheal tubes (ETTs) and other airway devices and equipment (eg, supraglottic laryngeal mask airway [LMA] devices, airway exchange catheters, bronchial blockers, tracheal tubes or stents, flexible and/or rigid bronchoscopy equipment, or a jet ventilator setup) may be necessary. Specific considerations for induction include (see 'Endotracheal tube selection' above and 'Supraglottic airway devices' above):
•If laser use in or near the airway is planned, we select a laser-resistant ETT or jet ventilation (JV) catheter, and extra care is taken to ensure that fraction of inspired oxygen concentration (FiO2) is <0.3 when combustion sources are used near the airway.
•If a highly flexible crush-resistant tube is necessary to prevent kinking, we select a wire-reinforced "armored" ETT.
•For procedures on the distal portion of the trachea or the carina, intubation of a mainstem bronchus may be necessary. A double lumen tube (DLT), or extra-long ETT may be selected.
●Choice of technique for induction of general anesthesia is based on surgical requirements and potential for compromised ventilation. Critical decisions include timing of endotracheal intubation (preinduction [awake] versus postinduction [asleep]), selection of an intravenous (IV) versus inhalation induction technique, whether to use a neuromuscular blocking agent (NMBA), and timing for initiation of positive pressure ventilation (PPV). General concepts for the induction sequence include (see 'Induction and airway management' above):
•If there are no risks for airway collapse or compromise during induction, we typically employ a standard IV induction with propofol 2 mg/kg and fentanyl 150 to 250 mcg, plus an NMBA. Administration of an NMBA is withheld until the ability to provide adequate PPV is ensured.
•If adequate oxygenation and ventilation during induction is thought to depend on maintenance of spontaneous negative pressure breathing so that anesthetized respiratory mechanics remain similar to the awake state, then an inhalation induction with sevoflurane may be selected.
•If there is significant risk that the anesthesiologist will be unable to secure the airway and initiate PPV after induction of general anesthesia, then an awake intubation technique is employed to maintain the patient's compensated functional physiology and respiratory mechanics during intubation.
•In rare cases, preinduction tracheostomy (or emergency cricothyroidotomy) may be necessary, or extracorporeal membrane oxygenation (ECMO) may be employed.
●Choice of ventilation technique (eg, standard PPV, JV, intermittent ventilation, spontaneous ventilation) depends on preexisting upper airway and tracheal anatomy, pulmonary pathology, and planned surgical interventions, particularly whether the trachea will be opened or remain intact. (See 'Options for intraoperative oxygenation and ventilation' above.)
●A total intravenous anesthetic (TIVA), rather than an inhalation technique, is typically selected when there will be unreliable delivery and end-tidal measurements of anesthetic gases (eg, during JV, intermittent apneic ventilation, frequent suctioning of the airway), or significant potential for leakage of inhaled anesthetic gas after the tracheal incision. Administration of an NMBA may be necessary to prevent coughing and facilitate surgery on the distal trachea. (See 'Maintenance' above.)
●Prerequisites for extubation include a thoroughly suctioned and dry oropharynx, complete return of neuromuscular function after reversal of the NMBA, optimal respiratory mechanics (typically aided by elevating the head of the bed approximately 30 degrees), adequate spontaneous tidal volumes and respiratory rate, and a conscious patient who can protect the airway after extubation. Supplemental oxygen is administered before and after extubation to maintain adequate oxygenation. (See 'Emergence and extubation' above.)
●After minor transverse cervical incision or percutaneous procedures, postoperative pain is usually minimal and easily treated with multimodal nonopioid systemic analgesic agents; long-acting opioids are avoided. If a thoracotomy is required, either thoracic epidural analgesia (TEA) or a paravertebral block (PVB) is typically employed to provide postoperative analgesia. (See 'Planning for postoperative analgesia' above and 'Pain management' above.)
●Patients undergoing high-risk tracheal surgical procedures are transported while monitored to an intensive care unit (ICU) for observation and further management; procedure-specific issues are communicated during the handoff procedure. (See 'Transfer to intensive care unit' above.)
