Anesthesia for patients with an anterior mediastinal mass

INTRODUCTION — Mediastinal masses may be small, slow-growing, and asymptomatic, or large, aggressive, symptomatic tumors (figure 1 and table 1). This topic discusses anesthetic care of patients undergoing a surgical procedure (eg, biopsy or resection) for diagnosis or treatment of an anterior mediastinal mass. Preanesthetic assessment, intraoperative anesthetic management, and early postoperative care are addressed.

Initial evaluation of mediastinal masses is discussed separately. (See "Approach to the adult patient with a mediastinal mass".)

PREANESTHETIC ASSESSMENT — The major goal of the preanesthesia consultation is to assess risk of airway or respiratory compromise and/or hemodynamic instability due to:

●Mass effect on the airway and lungs [1-4].

●Mass effect on major cardiovascular structures (ie, superior vena cava, right atrium, pulmonary artery, aorta, or innominate artery) [3,5,6]. Compression of these structures may cause cardiovascular collapse.

●Possible adverse consequences of anesthetic induction due to loss of the awake patient's compensatory mechanisms, including:

•Shifting mass effects with positional changes (eg, sitting to supine), resulting in compression of airway structures and great vessels.

•Loss of airway patency (ie, airway obstruction) due to relaxation of the airway muscles after administration of neuromuscular blocking agents (NMBAs).

•Increased intrathoracic pressure with decreased venous return to the heart during transition from spontaneous negative pressure ventilation to controlled positive pressure ventilation (PPV).

•Arterial and venodilation caused by administration of anesthetic induction agents.

●Possible adverse consequences of surgical manipulation and resection of the mass, including:

•Compression of airway structures and/or great vessels.

•Loss of airway continuity or patency due to planned resection or unplanned injury to the trachea or other airway structures.

•Hemorrhage due to injury of the heart and great vessels adjacent or adherent to the mass.

The anesthesiologist evaluates the patient's medical history, physical examination, and current functional status, as well as imaging and other studies defining mass location and pathology, in order to develop an anesthetic plan (table 1) [7,8]. Also, the anesthesiologist must understand the proposed surgical procedure. (See 'Considerations for specific surgical procedures' below.)

Focused history and examination — The history focuses on [7,8]:

●Local symptoms related to the size of the tumor and its effects on adjacent intrathoracic organs (eg, chest pain, dyspnea, dysphagia, syncopal or near-syncopal episodes). (See "Approach to the adult patient with a mediastinal mass", section on 'History and physical examination'.)

●Systemic symptoms due to paraneoplastic syndromes (in particular, a thymic mass secreting antiacetylcholine receptor antibodies, causing myasthenia gravis). (See "Clinical presentation and management of thymoma and thymic carcinoma", section on 'Paraneoplastic disorders'.)

The physical examination focuses on signs associated with mass effects including [7,8] (see "Approach to the adult patient with a mediastinal mass", section on 'History and physical examination'):

●Tachypnea, dyspnea, hoarseness, cough, stridor, or hemoptysis, with assessment of:

•Degree of severity of any of these signs.

•Exacerbating factors. If a supine position exacerbates dyspnea, to what degree does this occur? Can the patient lie flat for only a few seconds [4], a few minutes, or indefinitely?

•Actions that alleviate symptoms and signs. If distress occurs in a certain position, what positional change alleviates the distress?

●Facial and/or upper extremity edema, which suggest obstruction of the superior vena cava (SVC) by a large mass (ie, SVC syndrome). Similarly, hoarseness may indicate vocal cord edema caused by SVC syndrome. The urgency of therapy to relieve malignant SVC obstruction (eg, endovascular stenting, radiation therapy, chemotherapy for chemotherapy-sensitive malignancies) depends on symptom severity. (See "Malignancy-related superior vena cava syndrome", section on 'Urgency of diagnosis and treatment'.)

Symptomatic SVC syndrome may affect anesthetic management with respect to induction and airway control, vascular access, and volume management, as discussed below. (See 'Anesthetic preparation and management' below.)

●Hypotension, suggesting the possibility of cardiac compression or tamponade.

Preoperative tests and interventions

●Imaging – Available imaging studies are reviewed to assess the relationship of the mediastinal mass to the airway, lungs, heart, and major blood vessels. Since imaging studies are performed in an awake patient, they do not always predict changes that can occur during and after induction of anesthesia.

Potentially available imaging studies include chest radiograph (CXR), computed tomography (CT), and magnetic resonance imaging (MRI) of the chest, heart, and spine, as well as radionuclide studies. These are discussed separately. (See "Approach to the adult patient with a mediastinal mass", section on 'Imaging'.)

●Pulmonary function tests – We do not routinely obtain pulmonary function tests (PFTs) in patients with mediastinal masses. Although spirometry and flow-volume loops may be available as part of a preoperative evaluation, these tests have minimal utility for patient management (eg, poor correlation of flow-volume loops with airway obstruction) [9,10].

●Chemotherapy and radiotherapy – Some patients have received chemotherapy or radiotherapy prior to surgery to reduce the mass effect and/or improve the likelihood of a complete surgical resection.

•Chemotherapy – Systemic chemotherapy may have side effects that influence anesthetic management. Gastrointestinal complications are common (eg, nausea and vomiting, mucositis, oral ulcerations, dysphagia and odynophagia, and gastritis), while cardiac, pulmonary, or neurotoxic side effects occur after administration of certain agents. Adverse effects of specific chemotherapeutic agents should be discussed with the patient's oncologist.

•Radiotherapy – Radiation to the mediastinum may result in dry mouth, airway swelling, airway friability, or esophagitis, with consequent dysphagia, poor oral intake, and dehydration. Scarring and fibrosis of connective tissue in the thoracic cavity may result in a need for high airway pressures (eg, peak pressure >30 mmHg) during PPV. (See "Radiation therapy techniques in cancer treatment", section on 'Radiation side effects'.)

CONSIDERATIONS FOR SPECIFIC SURGICAL PROCEDURES — Patients with an anterior mediastinal mass may be undergoing a diagnostic procedure (eg, biopsy) or a therapeutic procedure (eg, resection). The required anesthetic depth for these procedures is a continuum ranging from local anesthesia with sedation and monitored anesthesia care (MAC) to general anesthesia (table 2). Preoperative discussions regarding the surgical plan are necessary to develop an anesthetic plan that includes appropriate airway management strategies, hemodynamic monitoring, and preparation for management of hemodynamic compromise or hemorrhage. (See 'Anesthetic preparation and management' below.)

Surgical techniques employed to biopsy or resect anterior mediastinal masses are briefly described below. Details regarding surgical techniques and complications of these procedures are described elsewhere.

Minimally invasive approaches

Cervical mediastinoscopy and anterior mediastinotomy (Chamberlain procedure)

●Cervical mediastinoscopy is performed via a midline transverse incision made immediately above the clavicular heads (figure 2). (See "Surgical evaluation of mediastinal lymphadenopathy", section on 'Anterior mediastinotomy'.)

●Anterior mediastinotomy (Chamberlain procedure) is a more invasive procedure than mediastinoscopy. A transverse incision is made immediately lateral and to the left of the sternum at the angle of Louie, along the second costal cartilage (figure 3). (See "Surgical evaluation of mediastinal lymphadenopathy", section on 'Anterior mediastinotomy'.)

In preparation for either a cervical mediastinoscopy or anterior mediastinotomy (Chamberlain procedure), the patient is placed in a supine position with a shoulder roll under the scapulae and the neck extended. Due to the position of the mediastinoscope behind the right innominate artery, pressure on this vessel by the instrument may cause a decrease or disappearance of right upper extremity pulses (figure 4). Thus, blood pressure is more accurately monitored in the left arm. Monitoring of the right upper extremity pulses in order to detect compression of the innominate artery is accomplished with pulse oximetry on a right-sided finger and/or a right radial intraarterial catheter.

Intraoperative complications include vascular injury, tracheal or esophageal injury, or pneumothorax [11-14]. Recurrent laryngeal nerve injury is typically discovered in the postoperative period manifesting as new and persistent hoarseness, dysphonia, or vocal fatigue [15,16]. These complications are more common in anterior mediastinotomy procedures. (See "Surgical evaluation of mediastinal lymphadenopathy", section on 'Complications of mediastinoscopy' and "Surgical evaluation of mediastinal lymphadenopathy", section on 'Anterior mediastinotomy'.)

Thoracoscopy — In preparation for video-assisted thoracoscopic surgery (VATS), intubation after anesthetic induction is performed using a double-lumen endotracheal tube or a bronchial blocker to achieve single-lung ventilation. Then the patient is placed in a lateral decubitus position secured with tape and/or sandbags. The operating room table is flexed to open the intercostal spaces (figure 5).

Intraoperative complications include pneumothorax, chylothorax, phrenic nerve injury, esophageal perforation, bleeding from vascular injury, or recurrent laryngeal nerve injury. Elective conversion from a VATS procedure to open thoracotomy in order to improve surgical exposure is not uncommon [17]. (See "Surgical evaluation of mediastinal lymphadenopathy", section on 'Thoracoscopy'.)

Further details regarding anesthetic and surgical management of thoracoscopy can be found elsewhere:

●(See "Anesthesia for video-assisted thoracoscopic surgery (VATS) for pulmonary resection".)

●(See "One lung ventilation: General principles".)

●(See "Lung isolation techniques".)

Open approaches (thoracotomy, sternotomy, thoracosternotomy) — An open exploration with a large incision is sometimes necessary to assess resectability of a mediastinal tumor. As with minimally invasive approaches, possible complications include vascular injury, tracheal or esophageal injury, or pneumothorax.

An open thoracotomy may be selected for an anterior mediastinal mass that is completely contained within one side of the chest. Intubation with a double-lumen endotracheal tube or a bronchial blocker is performed to achieve single-lung ventilation. (See "Anesthesia for open pulmonary resection" and "One lung ventilation: General principles" and "Lung isolation techniques".)

Most anterior mediastinal masses that cross the midline require a sternotomy, usually a standard median sternotomy. If the mass extends into the chest on one side only, a hemi-clamshell incision may provide adequate exposure for complete resection (figure 6). If the mass extends below the pulmonary hila on both sides, a clamshell incision is usually selected (figure 7).

Occasionally, a patient receives a large incision for a short procedure that turns out to be only exploratory. Anesthetic management of the patient must be planned so that the patient can either be rapidly awakened after a short procedure (eg, initial use of short-acting agents) or safely managed for a prolonged procedure (eg, adequate vascular access, appropriate hemodynamic monitoring, fastidious positioning and padding, and temperature control).

In cases with large incisions, postoperative pain control is an important consideration. In cooperative patients who will have a large incision, we use epidural analgesia to achieve postoperative pain control if there are no contraindications (see 'Planned epidural analgesia' below). For unilateral procedures (eg, thoracotomy), paravertebral block on the side of the surgery is a good alternative to epidural analgesia.

ANESTHETIC PREPARATION AND MANAGEMENT

Vascular access — If bleeding risk is high (eg, a large mass adjacent or adherent to vital structures), we obtain at least two large-bore peripheral catheters and/or large-bore central venous access. These factors also determine optimal sites for venous access and whether it is prudent to ensure central access before initiating induction of anesthesia.

A mass effect on certain branches of the venous vasculature may result in partial or full occlusion of venous drainage in the upper body, which may render central access useless at a compromised location. For example, if jugular and upper extremity venous engorgement is present in a patient with superior vena cava (SVC) syndrome, there is a high likelihood that upper caval flow is completely occluded and that induction of general anesthesia will cause cardiovascular collapse. In such cases, we insert catheters that drain into the inferior vena cava (IVC) prior to induction of anesthesia [4]. We typically use either two large-bore peripheral catheters in the lower extremities or a single large-bore catheter in a femoral vein. In patients with difficult peripheral vascular access, dual central venous catheters may be placed, with one catheter draining into the SVC and the other draining into the IVC. Thus, the IVC catheter would be used during surgery until mass resection is complete and then subsequently discontinued, while the SVC catheter would be used in the postoperative period.

Blood availability — Availability of blood products, as well as rapid infusion devices, should be ensured for patients with a large mediastinal mass in a critical location. Other preparations include preoperative communication with the surgeon regarding estimates of potential blood loss, as well as communication with the blood bank if massive transfusion is a possibility.

Planned epidural analgesia — If epidural analgesia is planned for postoperative pain management (eg, for thoracotomy, sternotomy, or clamshell incision) (see 'Open approaches (thoracotomy, sternotomy, thoracosternotomy)' above), placement should be accomplished before induction of anesthesia.

We avoid the possibility of inducing a sympathectomy in a patient who might develop hypotension during anesthetic induction or during the surgical procedure itself. Thus, we use conservative epidural test doses of a local anesthetic agent. Although we administer epidural opioids prior to surgical incision to provide supplemental analgesia, we avoid full activation of the epidural (eg, bolus dosing with a local anesthetic agent or initiation of local anesthetic infusion) until the mass has been resected and the patient is hemodynamically stable. (See "Approach to the management of acute pain in adults", section on 'Regional anesthesia techniques'.)

In the postoperative period, a high thoracic epidural (eg, at the T2 through T5 level) is often used to manage sternotomy pain. However, the superior area of the sternal incision may not be adequately covered, and supplemental analgesia may be necessary [18]. (See "Approach to the management of acute pain in adults", section on 'Options for managing postoperative analgesia'.)

Planned cardiopulmonary bypass — The surgeon may decide to employ cardiopulmonary bypass (CPB) in cases with a high likelihood of cardiovascular collapse or complete tracheal obstruction during induction of anesthesia or during the surgical intervention. Having a "standby" CPB team is usually futile in such situations because the time required to cannulate major blood vessels and initiate bypass is at least 10 minutes. Thus, if the size and/or location of the mass raise suspicion for the possibility of complete obstruction of the airway or major blood vessels during anesthetic induction, the surgical team may insert the necessary cannulas for femoral vein-to-femoral artery CPB or, very rarely, extracorporeal membrane oxygenation (ECMO). In these cases, CPB or ECMO may be initiated before induction of anesthesia [7,19,20]. The anesthesiologist must be prepared for sedation during cannula insertion, heparin administration prior to CPB, and administration of vasoactive agents and protamine during and after weaning from CPB. (See "Weaning from cardiopulmonary bypass".)

Typically, actions performed by the anesthesiologist include:

●Insertion of an intraarterial catheter and a CVC in a lower extremity prior to induction of general anesthesia.

●Titration of sedation with midazolam (eg, 1 to 4 mg administered in increments) and ketamine (eg, 0.5 to 1 mg/kg) to provide amnesia and analgesia during surgical cannulation of femoral arterial and venous vessels.

●Administration of a dose of heparin to achieve systemic anticoagulation shortly before initiation of partial CPB. (See "Blood management and anticoagulation for cardiopulmonary bypass", section on 'Heparin administration and monitoring'.)

●Induction of general anesthesia once the surgical team has determined that CPB can be established without difficulty. If anesthetic induction causes severe hemodynamic instability, then full CPB is initiated.

●Securing the airway as quickly as possible after induction of anesthesia. (See 'Airway management during induction' below.)

●Preparation of vasoactive infusions and protamine to achieve weaning from CPB after surgical resection or debulking of the mediastinal mass. (See "Weaning from cardiopulmonary bypass".)

Induction of anesthesia — The anesthesiologist should ensure that the surgeon is present when anesthesia is induced.

Choice of induction technique is determined by severity of symptoms and degree of anatomic and physiologic disruption caused by the mass. The two major concerns during induction of anesthesia in patients with an anterior mediastinal mass are:

●Airway or respiratory compromise (see 'Airway management during induction' below)

●Cardiovascular collapse (see 'Hemodynamic management during induction' below)

If respiratory compromise or hemodynamic instability occurs during induction of anesthesia, the knowledge gleaned during the preoperative history and physical examination may be useful to avoid catastrophic cardiovascular collapse (see 'Focused history and examination' above). For example, a simple postural change may stabilize the patient, allowing time for the surgical team to employ a definitive solution.

Airway management — Choice of airway equipment depends on airway pathology and surgical needs. Options that might be used are prepared prior to induction of general anesthesia or are immediately available in the operating room.

Preparation for airway control — Preparations for control of the airway before attempted induction of general anesthesia depend on the size and location of the mass, as well as the planned surgical procedure (see 'Considerations for specific surgical procedures' above). These may include:

●Preparation of an assortment of specialized endotracheal tubes (ETTs), such as:

•A reinforced ETT with less collapsibility and more flexibility if the mass is causing tracheal compression.

•A longer microlaryngoscopy tube (MLT) if the distal trachea is compressed.

•A double-lumen endobronchial tube (DLT) or bronchial blocker if single-lung ventilation will be necessary [21]. (See "One lung ventilation: General principles" and "Lung isolation techniques".)

●Preparation of a flexible bronchoscope for awake intubation or for checking the position of a double-lumen ETT or bronchial blocker after intubation. (See "Anesthesia for adult bronchoscopy", section on 'Anesthetic techniques for flexible bronchoscopy'.)

●Ensuring availability of a rigid bronchoscope for use if loss of airway patency is a possibility. (See "Anesthesia for adult bronchoscopy", section on 'General anesthesia for rigid bronchoscopy'.)

Airway management during induction — Mediastinal masses can cause either restrictive or obstructive airway or respiratory compromise, which may be exacerbated during induction of general anesthesia. Loss of airway patency and/or respiratory insufficiency may occur due to loss of the awake patient's compensatory mechanisms, effects of neuromuscular blocking agents (NMBAs), or transition from spontaneous ventilation to controlled positive pressure ventilation (PPV).

Airway monitoring and management strategies during induction include:

●Standard airway monitoring – Standard continuous monitoring includes pulse oximetry (SpO₂) and end-tidal CO₂. After the airway has been secured, airway pressure and volume are monitored. High airway pressures (eg, peak pressure >30 cmH₂O) may be required during PPV due to compression of the lungs by the mass itself or by surgical manipulation, or because of previous radiation therapy with resultant scarring and fibrosis.

●Positioning – If the patient has moderate to severe dyspnea in the supine position, the back is maintained in an upright position during induction and/or intubation [4,8].

●Selection of airway equipment and planning for possible airway obstruction – Selection of airway equipment depends on both airway pathology and surgical requirements. Due to the uncertainty of airway control during and after induction of general anesthesia, equipment appropriate for various scenarios should be available, as described below.

Options for airway management before, during, and after induction of anesthesia include:

•Awake intubation with flexible bronchoscopy – In some patients, the transition from sitting to supine position and/or from spontaneous (negative pressure) to PPV during induction can result in disruption of critical compensatory mechanisms, with consequent airway obstruction and/or cardiovascular collapse (see 'Preanesthetic assessment' above). For example, patients with facial, upper extremity, or vocal cord edema due to SVC syndrome have a high likelihood of airway collapse and obstruction during induction of general anesthesia. In such cases, awake intubation using flexible bronchoscopy is performed, with the patient breathing spontaneously, prior to induction of general anesthesia. (See "Flexible scope intubation for anesthesia".)

•Postinduction examination with flexible bronchoscopy – If preoperative imaging suggests possible invasion or compression of the trachea or bronchi, flexible bronchoscopy may be used to thoroughly evaluate the trachea and mainstem bronchi immediately following induction but prior to definitive airway control (ie, endotracheal intubation). Visualization with flexible bronchoscopy provides real-time information that may have been missed by radiographic evaluation, including dynamic airway collapse due to induction of anesthesia, mass effects, and/or changes that occur during positioning. Typically, if flexible bronchoscopy is planned immediately after induction, a supraglottic airway device is placed to serve as a conduit for the bronchoscope.

Also, direct visualization with flexible bronchoscopy may be employed in order to properly position a specialized ETT. For example:

-Reinforced ETT – If examination with flexible bronchoscopy reveals that the trachea is significantly compressed, then a reinforced ETT with less collapsibility and more flexibility is typically preferred, rather than a standard ETT.

-Long ETT – If the compressed portion of the trachea is either significant in length or is distally located, a longer tube may be required (eg, a MLT or a DLT).

•Use of a video DLT – If lung isolation is indicated for the surgical approach, a left-sided video double-lumen endobronchial tube (DLT) may be used to visualize the internal airway conduit, including the carina and right main stem bronchus. This facilitates initial placement or the DLT as well as verification of final position of the tube after positioning the patient for the surgical procedure [22-24].

•Maintenance of spontaneous ventilation during induction – In patients with SVC syndrome, as noted above, spontaneous ventilation may be maintained throughout induction of anesthesia by employing an inhalation anesthetic induction technique, due to the high risk of cardiovascular collapse during PPV. We continue to maintain spontaneous ventilation after intubation of the trachea if the patient becomes hemodynamically unstable in order to avoid the reduction in preload that occurs with PPV. Rarely, preservation of spontaneous ventilation must be maintained until after surgical control of the mass has been accomplished (eg, with partial excision) [4], or cardiopulmonary bypass (CPB) has been established for control of oxygenation and ventilation. (See "Induction of general anesthesia: Overview", section on 'Inhalation anesthetic induction'.)

Although concerns that muscle paralysis and PPV may worsen segmental airway compression leading to airway collapse and inability to ventilate, evidence to support this concern is scant. One prospective observational study in 17 patients noted no significant dynamic changes from baseline in the anterior-posterior diameter of the compressed segment of the central airway after induction of general anesthesia with spontaneous ventilation, PPV, or PPV with neuromuscular blockade [25].

•Rigid bronchoscopy – If loss of airway patency occurs during induction of anesthesia, with inability to advance a flexible bronchoscope or an ETT, then the surgeon may need to use rigid bronchoscopy, and the anesthesiologist provides jet ventilation [26].

Airway management during maintenance — Continuous confirmation of airway patency, as well as adequacy of oxygenation and ventilation, is necessary throughout the surgical procedure, particularly when a mediastinal mass is proximate to, compresses, or invades airway structures. Possible intraoperative problems include shifting of the mass effect due to surgical compression, surgical trauma (eg, inadvertent breach of the airway), airway collapse due to tracheomalacia, malposition of the ETT, or development of high airway pressure during PPV. Techniques to manage these problems include:

●Monitoring with direct visualization using flexible bronchoscopy – Intraoperative flexible fiberoptic bronchoscopy (FOB) may be used to visualize the internal airway conduit [1]. If the patient develops respiratory compromise, FOB allows rapid diagnosis and correction.

●Monitoring with direct visualization using a video DLT – If a video double-lumen endobronchial tube (DLT) has been placed due to the need for lung isolation during surgery, real-time visualization is possible for an anterior mediastinal mass located distal to the tracheal lumen of the DLT and/or involving the right main stem bronchus. Compared with a standard DLT, the video DLT requires significantly less FOB use to correct dislodgement of the DLT during patient repositioning and during surgery [22-24].

●Cross-field ventilation – In some cases, cross-field ventilation is required. Examples include planned resection of the trachea (eg, tumor that is adherent to the trachea and cannot be "peeled off") or inadvertent tracheal injury resulting in unplanned resection. In such cases, the surgeon directly intubates the main conducting airway distal to the affected tracheal area and connects the ETT to the breathing circuit tubing (or to a jet ventilator apparatus and tubing). The proximal end of such tubing (with extensions) is passed over the surgical drapes to the anesthesiologist to be immediately connected to the anesthesia machine (or to an oxygen supply for jet ventilation). This cross-field ventilation technique will ensure continued oxygenation and ventilation in a patient with breached airway anatomy.

In such cases, volatile anesthetics should be discontinued to avoid inhalation by the surgical team, and total intravenous anesthesia (TIVA) should be instituted to ensure adequate anesthetic depth. Also, to reduce the risk of airway fire, the anesthesiologist discontinues nitrous oxide and reduces FiO₂ to <30 percent or the minimum level required to avoid hypoxia. Adequate time should be allowed for reduction of both the fraction of inspired oxygen (FiO₂) and the fraction of expired oxygen (FeO₂) to this safe level (<30 percent) before the surgeon uses electrosurgery or any other ignition source. (See "Fire safety in the operating room", section on 'Limit oxygen administration and avoid nitrous oxide'.)

Hemodynamic management

Hemodynamic monitoring — Standard hemodynamic monitors are always employed (eg, electrocardiogram [ECG] and noninvasive blood pressure monitoring). We also insert an intraarterial catheter and a central venous catheter in patients who may develop airway obstruction and/or hemodynamic compromise during anesthesia and surgery.

Intraarterial catheter — Intraarterial catheter location is determined by knowledge of the size and location of the mediastinal mass and consequent effects on right- and/or left-sided upper extremity circulation. For example, patients with SVC syndrome may have compression of subclavian vessels that affects arterial flow in the brachial and radial arteries. If there is a high likelihood of vascular occlusion in one upper extremity, we place intraarterial catheters in both upper extremities (ie, radial and axillary). If there is a high likelihood of vascular occlusion in both upper extremities (eg, patients with SVC syndrome), we insert an intraarterial catheter in a lower extremity (ie, femoral artery).

●Continuous monitoring of blood pressure – In patients who need an intraarterial catheter due to mass effect on major cardiovascular structures and circulation, we insert this prior to induction of anesthesia in order to obtain beat-to-beat monitoring of blood pressure during and after induction.

●Automated computation of dynamic parameters to guide fluid therapy – If equipment and expertise are available, automated computation of dynamic variables obtained from the intraarterial waveform is often used to guide fluid therapy in patients with a large mediastinal mass. Significant (>10 to 15 percent) respirophasic variations in systolic pressure, pulse pressure, or stroke volume suggest that cardiac output will increase in response to a fluid challenge (table 3) [27-33]. (See "Intraoperative fluid management", section on 'Dynamic parameters to assess volume responsiveness' and "Intraoperative fluid management", section on 'Goal-directed fluid therapy'.)

However, this technology is limited in many patients undergoing surgery for a mediastinal mass, including the following circumstances [34]:

•Spontaneous ventilation

•Open chest procedure

•High end-expiratory pressures (ie, >40 mmHg)

•Tidal volumes <8 mL/kg

In these circumstances, we use visual estimation of respirophasic variations in the intraarterial pressure waveform, which is adequate and may be comparable to automated computation of respirophasic variations (figure 8) [35].

●Blood samples for arterial blood gases and other laboratory values – An intraarterial catheter also provides a means for efficiently obtaining blood samples to measure arterial blood gases, hemoglobin/hematocrit, coagulation, electrolytes, and glucose levels.

Central venous catheter

●Continuous monitoring of central venous pressure – A central venous catheter (CVC) allows continuous monitoring of central venous pressure (CVP) as an estimate of intravascular volume status. CVP measurements reflect right ventricular filling pressure. Although it has limitations, CVP is the most commonly used "static" parameter to assess intravascular volume status (ie, preload) [36,37]. (See "Intraoperative fluid management".)

●Adequate vascular access – Patients at risk for significant blood loss usually receive a CVC due to the possible need for transfusions and emergency resuscitation, particularly if it is not possible to obtain at least two large-bore peripheral venous catheters. For patients with SVC syndrome requiring central venous access, the CVC is placed in the femoral vein, as noted above. (See 'Preanesthetic assessment' above and 'Vascular access' above.)

●Blood samples for venous blood gases and other laboratory values – In the absence of an intraarterial catheter, the CVC also provides a means to obtain blood samples to measure venous blood gases, hemoglobin/hematocrit, coagulation, electrolytes, and glucose levels.

Other monitoring modalities

●Transesophageal echocardiography – Since transesophageal echocardiography (TEE) allows continuous visualization of the left and right ventricles, it is particularly useful when the anterior mediastinal mass is compressing the heart or other major vascular structures, or is attached to the myocardium or pericardium [4].

TEE also allows qualitative estimation of ventricular volume (ie, left and right ventricular size) and continuous evaluation of cardiac function (ie, global, regional, systolic, and diastolic function of both the left and right ventricles). This information is useful to guide volume management and titration of vasoactive infusions [38]. (See "Intraoperative transesophageal echocardiography for noncardiac surgery".)

TEE monitoring is an option if equipment and expertise are available, if the mediastinal mass does not impact the esophagus, and if there are no other contraindications (eg, history of upper gastrointestinal bleeding or other severe esophageal or gastric disorder) [38,39].

Rescue TEE can be life-saving if hemodynamic instability or collapse occurs [40]. (See "Intraoperative rescue transesophageal echocardiography (TEE)", section on 'General indications' and "Intraoperative rescue transesophageal echocardiography (TEE)", section on 'Key views'.)

●Pulmonary artery catheter – A pulmonary artery catheter (PAC) is rarely used, due to evidence that PAC monitoring does not improve outcome [41], and patients with a mediastinal mass are at risk for vascular perforation or other difficulty with PAC placement. (See "Pulmonary artery catheterization: Indications, contraindications, and complications in adults".)

Hemodynamic management during induction — Cardiovascular collapse may occur during induction of anesthesia in patients with preoperative signs and symptoms of cardiovascular compromise secondary to mediastinal mass effects (eg, patients with SVC syndrome) (see 'Focused history and examination' above). Profound hypotension may be caused by shifting mass effects with positional change (due to compression of the great vessels), hemodynamic effects of anesthetic induction agents (due to arterial and venodilation and direct myocardial depressant effects), or transition from spontaneous negative pressure ventilation to controlled PPV (due to increased intrathoracic pressure and decreased venous return to the heart).

During induction, techniques to maintain baseline cardiovascular stability include:

●Maintaining the least symptomatic position during induction (typically sitting or lateral decubitus position).

●Using induction agents that have minimal or favorable effects on hemodynamics if an intravenous (IV) induction technique is selected (eg, etomidate or ketamine).

●Administering adequate volume (eg, crystalloid solution) throughout the induction period in order to maintain central venous and arterial blood pressures.

●Administering inotropes and/or vasopressors if necessary [4] (table 4).

●Maintaining spontaneous ventilation using an inhalation or intravenous induction technique in selected patients [4]. (See 'Airway management during induction' above.)

Hemodynamic management during maintenance — Intraoperative hemodynamic changes may occur due to shifting mass effects, surgical manipulation of the heart or major blood vessels, changes in PPV causing increased intrathoracic pressure, or hemorrhage due to inadvertent injury to cardiovascular structures. Also, dynamic changes in intraoperative volume requirements may occur due to significant bleeding or cardiovascular compression.

Intraoperative techniques to maintain hemodynamic stability include:

●Optimizing volume status. We administer crystalloid solution during open thoracic surgery for a mediastinal mass (see 'Open approaches (thoracotomy, sternotomy, thoracosternotomy)' above), limiting total intraoperative solution to 1.5 to 2 L in the absence of ongoing blood loss [42,43]. This restrictive fluid strategy may reduce pulmonary complications to facilitate early extubation. While the fluid regimen should be individualized to optimize cardiac output (CO) and O₂ delivery (figure 8), excessive fluid administration (ie, >3 L in the 24 hours of the perioperative period) has been associated with acute lung injury and delayed recovery after open thoracic surgery [44]. Since perioperative fluid restriction ≤3 mL/kg/hour is not a risk factor for postoperative acute kidney injury after thoracic surgery, we do not attempt to reverse intraoperative oliguria with fluid administration [44]. (See "Anesthesia for open pulmonary resection", section on 'Fluid and hemodynamic management'.)

Colloids may be used to replace an equivalent volume of blood loss, while red blood cells (RBCs) are transfused only if necessary, to maintain hemoglobin ≥8 g/dL. However, hydroxyethyl starch (HES) solutions are generally avoided due to concerns regarding renal dysfunction after thoracic surgery [44].

●Administering inotropes and/or vasopressors if necessary (table 4) [4].

●Use of short-acting anesthetic agents that can be rapidly titrated to minimize hemodynamic effects during maintenance of anesthesia.

●Delay of epidural activation until the mass has been resected. The sympathectomy resulting from local anesthetic administration via an epidural may contribute to intraoperative hypotension. (See 'Planned epidural analgesia' above.)

●Continuous communication with the surgical team to ensure their awareness of the severity of hemodynamic changes occurring during manipulation or due to blood loss.

●Communication with the blood bank, as appropriate, for management of anticipated or actual bleeding, and use of rapid transfusion devices if necessary. (See 'Blood availability' above.)

Emergence and extubation

●Final bronchoscopy – Flexible bronchoscopy may be necessary to assess airway patency and continuity following resection of an adjacent or adherent mass, or to perform suction and lavage under direct vision in patients who have excessive airway secretions. This is accomplished during the transition from mechanical PPV to spontaneous negative pressure ventilation.

If a double-lumen endotracheal tube (DLT) was placed for lung isolation, a thorough evaluation of the airway may not be possible until after extubation. Patients who require evaluation of tracheobronchial anatomy with flexible bronchoscopy are extubated deep. The DLT is replaced with a supraglottic airway device (eg, a laryngeal mask airway) to facilitate insertion of the flexible bronchoscope. (See "Anesthesia for open pulmonary resection", section on 'Final bronchoscopy before emergence'.)

●Extubation – If the patient is to be extubated, a smooth and controlled extubation is preferable. This is particularly important in patients with significant tracheomalacia and/or in procedures where the tracheobronchial tree was inadvertently breached or partially resected, with subsequent reanastomosis. Coughing and "bucking" during emergence increases airway pressure, which may compromise a tracheal anastomosis, causing bleeding and airway leak.

Thus, we extubate these patients while they are "deep" (ie, still fully anesthetized). We accomplish this either by temporarily increasing the concentration of volatile anesthetic agent or by temporarily infusing rapid-acting IV agents (eg, remifentanil 0.1 to 0.3 mcg/kg/minute, propofol 50 to 200 mcg/kg/minute, or dexmedetomidine 0.2 to 0.7 mcg/kg/hour). The goal is to minimize airway reactivity, coughing, and sympathetic responses to the endotracheal tube (eg, hypertension and tachycardia).

●Planned postoperative ventilation – If extubation is not feasible due to the surgical procedure itself or the patient's inability to meet standard extubation criteria (see "Extubation management in the adult intensive care unit"), then transportation to the intensive care unit is accomplished with the endotracheal tube (ETT) in place. The double lumen tube can be replaced with a single lumen tube by using a tube exchanger. The patient remains intubated with controlled ventilation until extubation is safe. (See "Anesthesia for open pulmonary resection", section on 'Final bronchoscopy before emergence'.)

POSTANESTHETIC MANAGEMENT

Emergency complications — In the immediate postoperative period, hemorrhage at the surgical site or evidence of airway compromise (due to edema, nerve damage, or tracheobronchial obstruction) requires emergency evaluation and management. The anesthesia care team must have a high index of suspicion for these events since they typically occur in the postanesthesia care unit (PACU). Also, the team must have capabilities for rapid intervention (eg, advanced airway control or massive transfusion) and available anesthesia personnel for a possible emergency return to the operating room. (See "Surgical evaluation of mediastinal lymphadenopathy", section on 'Complications of mediastinoscopy' and "Surgical evaluation of mediastinal lymphadenopathy", section on 'Complications of anterior mediastinotomy' and "Surgical evaluation of mediastinal lymphadenopathy", section on 'Complications of thoracoscopy'.)

Pain management — Regional techniques for pain management include epidural analgesia if a catheter was previously inserted (see 'Planned epidural analgesia' above) or intercostal blocks performed by the surgeon or anesthesiologist.

Oral pain medications may suffice after minimally invasive procedures (eg, mediastinoscopy, mediastinotomy, or thoracoscopy with a small incision). If necessary for control of moderate to severe pain, intravenous (IV) patient-controlled analgesia (PCA) is an option for inpatients. (See "Approach to the management of acute pain in adults".)

MANAGEMENT OF PEDIATRIC PATIENTS WITH A MEDIASTINAL MASS — Pediatric patients who have a mediastinal mass present unique challenges. Generally, such cases are best managed in a tertiary care facility with experience in managing pediatric patients with complex surgical diseases.

Unlike adult patients, many procedures cannot be performed under local sedation in pediatric patients. However, children with symptomatic anterior mediastinal mass had no serious complications during general anesthesia in one retrospective review [45]. Spontaneous ventilation is typically preferred during induction of general anesthesia to avoid compressive effects of an anterior mediastinal mass [45,46]. Various anesthetic agents have been judiciously used during such cases including volatile anesthetics, ketamine, dexmedetomidine, and propofol [46].

SUMMARY AND RECOMMENDATIONS

●Preanesthetic assessment – The major goal of the preanesthesia consultation is to assess risk due to (see 'Preanesthetic assessment' above):

•Airway or respiratory compromise

-During induction, exacerbation of mass effects on the airway may occur due to loss of the awake patient’s compensatory mechanisms with position change, neuromuscular blockade, or transition from spontaneous to PPV. (See 'Airway management during induction' above.)

-During maintenance, loss of airway patency may occur due to surgical breach of the airway, shifting of the mass effect due to compression, airway collapse due to tracheomalacia, malposition of the endotracheal tube (ETT), or development of high airway pressure during PPV. (See 'Airway management during maintenance' above.)

•Cardiovascular collapse

-During induction, cardiovascular collapse may occur due to shifting mass effects with position change (eg, compression of the great vessels), hemodynamic effects of anesthetic induction agents, or PPV. (See 'Hemodynamic management during induction' above.)

-During maintenance, hemodynamic instability may occur due to shifting mass effects, surgical compression, or hemorrhagic injury of major vascular structures. (See 'Hemodynamic management during maintenance' above.)

●Surgical considerations

•Depending upon the size and location of the mass and the planned surgical procedure (see 'Preanesthetic assessment' above), anesthetic management may include at least two large-bore peripheral catheters or large-bore central venous access (see 'Vascular access' above), as well as ensuring availability of blood products and a rapid infusion device. (See 'Blood availability' above.)

•In rare cases, initiation of cardiopulmonary bypass (CPB) is planned before induction of general anesthesia. (See 'Planned cardiopulmonary bypass' above.)

•The surgeon should be present when anesthesia is induced. (See 'Induction of anesthesia' above.)

●Airway management – Airway management strategies during induction and maintenance of general anesthesia may include (see 'Airway management' above):

•Preparation for control of a difficult airway

•Upright positioning if the patient does not tolerate the supine position

•Awake intubation using flexible bronchoscopy

•Selection of a specialized ETT (eg, a reinforced ETT, long microlaryngoscopy tube [MLT], double-lumen endobronchial tube [DLT], or video DLT)

•Maintenance of spontaneous ventilation using inhalation induction

•Flexible bronchoscopy to evaluate the trachea and mainstem bronchi immediately after induction or with subsequent respiratory compromise

•Rigid bronchoscopy if complete airway compromise occurs during induction or maintenance of anesthesia

•Cross-field ventilation with direct surgical intubation of the distal airway

●Hemodynamic management – Hemodynamic management strategies during induction and maintenance of general anesthesia may include (see 'Hemodynamic management' above):

•Insertion of an intraarterial catheter and a central venous catheter. (See 'Hemodynamic monitoring' above.)

•Maintaining the least symptomatic position during induction (typically sitting or lateral decubitus position).

•Use of induction agents that have minimal effects on hemodynamics (eg, etomidate or ketamine).

•Delay of epidural activation (eg, administration of local anesthetics) to avoid intraoperative sympathectomy until after resection of the mass. (See 'Planned epidural analgesia' above.)

•Optimizing volume status.

•Administering inotropes and/or vasopressors if necessary (table 4).

•Using short-acting anesthetic agents that can be rapidly titrated to minimize hemodynamic effects.

•Communication with the blood bank for management of bleeding, with use of rapid transfusion devices if necessary. (See 'Blood availability' above.)

●Emergence and extubation – The following techniques may be employed (see 'Emergence and extubation' above):

•Extubation while "deep" (ie, still fully anesthetized) to avoid coughing with consequent bleeding and airway leak, particularly in patients with tracheomalacia or tracheobronchial resection and reanastomosis.

•Examination via flexible bronchoscopy prior to extubation (eg, to assess airway patency after resection or to manage secretions with suction and lavage).

●Postanesthetic management – Postoperative hemorrhage or airway compromise requires emergency intervention (eg, advanced airway control, massive transfusion) and/or immediate return to the operating room. (See 'Postanesthetic management' above.)