Episode #283 How To Plan, Induce, And Recover Patients With Anterior Mediastinal Mass Without Triggering Collapse

Hello and welcome back to the Anesthesia Patient Safety Podcast. My name is Alli Bechtel, and I am your host. Thank you for joining us for another show. When was the last time that you provided anesthesia care for a patient with an anterior mediastinal mass? Did just hearing the words anterior mediastinal mass cause your heart rate to increase? These cases are rare and have the potential for airway and cardiovascular compromise and collapse. Anesthesia professionals need to be prepared, remain vigilant, and stay up to date with the latest in perioperative patient safety when it comes to the anesthetic management for patients with anterior mediastinal mass. Today, we will be reviewing recent studies and updates in anesthetic considerations for management of pediatric patients with anterior mediastinal mass as well as including important details for adult patients. So, stay tuned.

Before we dive further into the episode today, we’d like to recognize Draeger Medical, a major corporate supporter of APSF. Draeger Medical has generously provided unrestricted support to further our vision that “no one shall be harmed by anesthesia care”. Thank you, Draeger Medical – we wouldn’t be able to do all that we do without you!”

Our featured article today is “Anesthetic Considerations for the Management of Patients with Anterior Mediastinal Mass” by Kavitha Raghavan and Joanna Rosing Paquin. This article was published online on September 2, 2025. This is an article between issues. To follow along, head over to APSF.org and click on the Newsletter heading. Second one down is Articles between issues. From there scroll down to September 2025 and our featured article. I will include a link in the show notes as well.

Let’s get started by reviewing the relevant anatomy. The pre-vascular or anterior mediastinum is bound by the following:

• Superiorly by the thoracic inlet
• Inferiorly by the diaphragm
• Anteriorly by the sternum
• Posteriorly by the pericardium
• And laterally by the parietal mediastinal pleura.

Within this space, you will find the thymus, lymph nodes, fat, and the left brachiocephalic vein. The visceral or middle mediastinum contains the trachea, esophagus, lymph notes, heart, ascending thoracic aorta, aortic arch, descending thoracic aorta, superior vena cava, intrapericardial pulmonary arteries, and thoracic duct. Finally, the paravertebral or posterior mediastinum contains soft tissue. Check out Figures 1,2, and 3 in the article. Figure 1 is a lateral chest radiograph that reveals that anterior, middle and posterior mediastinal compartments. Figure 2 is a sagittal section of a Chest CT and Figure 3 is an axial section of a Chest CT with arrows highlighting the anterior, middle and posterior mediastinum.

Next, we are going to review the incidence and types of anterior mediastinal masses. These may be metastatic lesions or originate from structures within or passing through the mediastinum and make up about 3% of thoracic tumors. There is a bimodal distribution with the peak incidence occurring in children under 10 years old and adults between the ages of 60-70 years old. Adult and pediatric anesthesia professionals need to be prepared to provide safe anesthesia care for these patients. The most common anterior mediastinal mass in adults are thymic lesions, followed by cysts and metastatic carcinomas while in children lymphomas are the most common followed by acute lymphoblastic leukemia and germ-cell tumors.

We often see patients in the operating room after their initial presentation. The clinical presentation for a patient with an anterior mediastinal mass depends on the speed of tumor growth and the amount of compression of adjacent structures. Symptoms may include the following: chest fullness, dyspnea, positional dyspnea including orthopnea, cough, stridor, hoarseness, dizziness, syncope, tachycardia, positional hypotension, and swelling of the face, neck, arms, and upper chest. Depending on the type of mass, patients may also present with fever, night sweats, and weight loss.

Prior to presenting for surgery, patients will need scans and studies to help guide the presumptive diagnosis, treatment planning, and risk stratification. Check out Figure 4 in the article to see a Chest X-ray that demonstrates mediastinal widening from an anterior mediastinal mass. Figure 5 shows the chest CT of a 13-year-old with  a right paratracheal soft tissue mass and associated tracheal compression, and Figure 6 is a chest CT of a 17-year-old with an anterior mediastinal mass with central airway and central vascular compression due to the bulky tumor with concerns for airway compromise.

Table 1 in the article describes the different diagnostic tests for anterior mediastinal mass evaluation. We are going to go through it now.

CT angiography with thin slices and cardiac gating to evaluate for the following:

• Mass characteristics include size, location, specific radiological characteristics.
• Structure of origin.
• The mass effect on adjacent structures.

Dynamic inspiration and expiration CT to look for dynamic airway compression but keep in mind that this may not be tolerated by many patients with large masses.

Transthoracic echocardiography to evaluate for the following:

• Compression of pulmonary artery (PA), pulmonary vein (PV) or left atrial compression leading to right ventricular (RV) dilatation.
• Pericardial effusion.
• Reduced systolic function or wall motion abnormalities
• And pulmonary function tests to determine peak expiratory flow rate which can help predict major postoperative respiratory complications especially in adults. Keep in mind that spirometry is less helpful for children due to limited cooperation with the test or the urgency of presentation.

Now, its time to review the pathophysiology and effects of anesthesia related to anterior mediastinal mass. In an upright healthy person, airway caliber increases during inspiration which reduces the resistance to airflow. The opposite occurs during expiration – decreased airway caliber and increased airway resistance. When we move to the supine position, there are decreases in functional residual capacity or FRC. Patients with compression due to anterior mediastinal mass may compensate by changing their body position and increasing inspiratory flow, expiratory flow, and expiratory time. These compensatory actions are compromised during anesthesia in the supine position from loss of muscle tone and the effects of gravity that normally helps to displace the mass away from the airway even during spontaneous ventilation. Additional effects include:

• Reduced lung volumes leading to increased dynamic airway resistance and decreased pulmonary compliance
• During positive pressure ventilation, airway caliber increases during inspiration, but decreases during expiration
• Air trapping can occur during expiration due to decreased expiratory flow leading to auto-positive end expiratory pressure or auto-PEEP if the expiratory time is not increased
• Reduced respiratory muscle tone following neuromuscular blockade leading to airway compression.

If we turn our attention to the cardiovascular system, we can see that awake patients even with major vascular compression may remain relatively asymptomatic. Anterior mediastinal masses may compress the superior vena cava leading to reduced venous return to the right atrium while compression of the right ventricle or pulmonary artery may decrease right cardiac outflow. Under anesthesia the following may occur:

• Loss of sympathetic tone
• Reduction in venous return
• Relative hypovolemia
• Increased intrathoracic pressure during positive pressure ventilation especially if there is air trapping leading to decreased venous return and right ventricular outflow.
• Patients with a pericardial effusion may have even more significant cardiovascular compromise.

Cardiovascular compromise may persist after extubation due to residual muscle weakness, increased work of breathing due to pain, sympathetic stimulation, and post-tumor resection trachea-bronchomalacia.

Before we induce general anesthesia for a patient with an anterior mediastinal mass, let’s discuss risk stratification. This can be done based on clinical signs and symptoms, tumor location, and diagnostic studies. There is increased perioperative risk depending on symptom severity, progression, and positional nature of the mass. Keep in mind that patients with the following signs have a higher risk of complications:

• Stridor
• Positional dyspnea
• Cyanosis
• And signs of superior vena cava syndrome such as upper body edema which indicates severe airway and vascular compression.

Did you know that tracheal compression greater than 50% is associated with higher risk in children than in adults who have firmer cartilage and larger-diameter airways? Here are a few more important considerations:

In adults, a higher mass to chest ratio is associated with post-extubation airway complications

Pericardial effusion and superior vena cava obstruction are associated with a higher risk for hemodynamic compromise

And for adults with peak expiratory flow rate less than 40% and with mixed obstructive restrictive patterns due to the mass, there is a higher risk for respiratory complications.

Check out Table 2 in the article for a risk stratification chart for adults. Let’s review it now.

Low risk criteria include: asymptomatic, mass to chest ratio less than 0.2, airway compression less than 50%, and no major vascular compression.

Moderate risk criteria include: gradual onset, mild to moderate symptoms, no orthopnea, mass to chest ratio between 0.2 and 0.5, airway compression less than 50% with symptoms, asymptomatic SVC or unilateral pulmonary artery compression

High risk criteria include: severe symptoms, onset in the last 6 months, cannot lie flat, mass to chest ratio greater than 0.5, airway compression greater than 50% with symptoms or with lower airway obstruction or with changes on PFTs, SVC syndrome and dyspnea, major pulmonary artery compression or pericardial effusion

And very high risk criteria include: major SVC and airway compression, bilateral pulmonary artery compression, and major VQ mismatch.

You can also check out Table 3 in the article for a risk stratification chart for pediatric patients and I will include it in the show notes as well.

Low risk criteria include asymptomatic, no radiographic airway, cardiac, or vascular compression

Moderate risk criteria include mild to moderate symptoms such as dyspnea or orthopnea, mild tracheal compression < 70%, and no bronchial compression

High risk criteria include the following:

• Severe symptoms (orthopnea, stridor, cyanosis)
• Tracheal compression > 70%, tracheal and bronchial compression.
• Cardiac tamponade physiology on echocardiogram
• Major vascular compression

Keep in mind that asymptomatic pediatric patients can have complications, but the risk is increased with the presence of 3 or more symptoms and an average mediastinal mass ratio of 0.56 is associated with a higher risk of respiratory and cardiovascular compromise. More recent studies have identified standardized tumor volume which estimates the tumor volume while accounting for the patient’s height, as a predictor for the risk of respiratory collapse in pediatric patients undergoing general anesthesia. I will put the equation for standardized tumor volume in the show notes as well.

Now, we are just about ready to head into the operating theatre, but first, what’s your plan for the aesthetic?

The planning phase is important and may involve a multidisciplinary team of oncologists, radiologists, surgeons, otolaryngologists, and anesthesia professionals to  discuss clinical presentation, risk categorization, procedural needs, and perioperative risk prior to undergoing diagnostic and therapeutic procedures. Patients may need to have a tumor, lymph node, or bone marrow biopsy to make a diagnosis. Pediatric patients may require central line placement for initiation of therapy. If possible, less invasive procedures such as PICC lines or lymph node biopsy from a superficial location should be considered. The anaesthetic technique will depend on the patient’s age, ability to tolerate anxiolysis or sedation, risk category, clinical condition, and planned procedure. The preferred location for these patients to undergo initial procedures is the operating room with immediate availability of experienced staff, airway devices, vascular access equipment, and medications. Rapid escalation of care is facilitated in the controlled setting of the operating room.

For less invasive procedures that do not require general anesthesia, you may consider anxiolysis or mild to moderate sedation with locoregional anaesthesia for cooperative children and adults. Options may include the following:

• Anxiolysis with intravenous midazolam
• Sedation with ketamine, dexmedetomidine, and remifentanil in combination with low-dose propofol

The benefits of ketamine and dexmedetomidine include preserved airway reflexes while remifentanil can be titrated rapidly to the desired effect. You may consider using routine anaesthetic techniques for asymptomatic patients at low risk who require general anesthesia for an invasive procedure.

For moderate to high-risk patients, the goals are to maintain spontaneous ventilation in an awake patient. You may need to avoid general anesthesia in order to avoid cardiorespiratory complications.

But what about moderate to high risk patients who need general anesthesia? This calls for preoperative planning and a discussion with the oncologists about pre-diagnosis steroids to reduce the tumor size and postponing the procedure until the tumor burden has been reduced if possible. Multidisciplinary planning is needed well before procedures requiring general anesthesia so that you have time to confirm the availability of resources including the presence of heliox, jet ventilation, rigid bronchoscopy, airway stenting, and ECMO canulation and to clarify the anticipated response times. This may not be something that can be accomplished on the morning of surgery. Patients at high risk for airway or cardiovascular collapse should considered for transfer to a center with an ECMO service to help keep them safe.

Now, we are in the operating room. Here are some of the considerations for general anesthesia for high risk patients.

• Adequate intravenous access in a lower extremity in case of superior vena cava obstruction
• Consideration for pre-induction arterial line
• Adequate pre-oxygenation
• Slow induction of anesthesia in a semi-sitting or comfortable position while maintaining spontaneous ventilation.
• Avoid muscle relaxation
• Consideration for awake intubation in cooperative patients, but this may be challenging for pediatric patients.
• Use of an armoured tube may be needed depending on the level of airway compression

Keep in mind that patients at moderate risk for airway collapse may be carefully intubated under general anesthesia with maintenance of spontaneous ventilation while high risk patients should be intubated awake or with mild sedation after airway topicalization with local anaesthetic.

Another consideration is the use of short acting medications that can be administered to deepen the anaesthetic and determine if the patient will tolerate positive pressure ventilation prior to administering muscle relaxants or ideally avoiding muscle relaxants all together.

The recommendation is to avoid positive pressure ventilation which may cause cardiovascular collapse due to air trapping. If positive pressure ventilation is needed, using a low respiratory rate with longer expiratory time can help avoid air trapping.

During patient positioning and prior to extubation, the use of fibreoptic bronchoscopy to visualize airway compression can be helpful to determine rescue positioning post-extubation and predict the need for postoperative non-invasive ventilation, airway stenting, or external tracheal stabilization.

Postoperatively, moderate and high-risk pediatric patients should be monitored in the intensive care unit

Adults at moderate to high risk with post-extubation narrowing greater than 50%, main stem bronchial compression, tracheomalacia, or abnormal spirometry prior to anesthesia should also be monitored postop in the ICU.

Check out Table 4 in the article for a list of emerging concepts in airway management and ventilation for patients with any central intrathoracic airway obstruction. This table is an excellent resource and reminds us about the traditional concepts and any updates that have emerged. For awake spontaneous ventilation, there is no change. Key traditional considerations include:

• Increase in airway caliber and inspiratory flow due to negative pressure generation during inspiration.
• Decrease in airway caliber during expiration compensated by prolonged expiratory phase and body positioning.

Next up, spontaneous ventilation during anesthesia. The emerging concepts reveal:

• No significant reduction in airway caliber during inspiration.
• Intact compensatory mechanism to increase expiratory time to offset reduction in expiratory airway caliber.

For positive pressure ventilation during anesthesia, the emerging concept supports that during inspiration, peak inspiratory flow and airway caliber are increased while during expiration, airway caliber is reduced back to baseline requiring increase in expiratory time to compensate for unchanged peak expiratory flow and avoiding air trapping.

The next category is positive pressure ventilation during anaesthesia with neuromuscular blockade. Traditionally, it was thought that there was a reduction in skeletal and smooth muscle tone during anesthesia and NMB worsens central airway obstruction resulting in inability to ventilate. The emerging concept is that there is no further changes in airway caliber, PIF, or PEF on administration of NMB than those that occur during PPV.

Finally, causes of hemodynamic collapse were traditionally thought to be air trapping and hyperventilation induced alkalosis. Now, the added emerging cause is tumor compression of the heart and major vessels.

Careful planning and management is crucial to help keep patients with anterior mediastinal masses safe and it is important to be prepared to manage complications. Airway obstruction during induction is more common in younger patients with rapidly growing tumors while complications during or after extubation is more common in older patients with slower growing tumors. When airway obstruction occurs, the priority is to relieve airway compression before hypoxic arrest. Important considerations include:

• Patient positioning guided by preprocedural imagine and patient’s symptoms
• Maximize oxygenation, maintain spontaneous ventilation, and support ventilation with CPAP.
• If there is still respiratory obstruction, the next step is physical stenting with a tracheal tube, a rigid bronchoscope, or an airway stent.
• If there is persistent airway collapse distal to the tracheal tube, ECMO should be initiated promptly. For high-risk patients who may need ECMO, the circuit should be primed and immediately available with patient prepared for ECMO cannulation prior to induction of anesthesia. Peripheral ven0-venous ECMO has been used for patients with tracheal compression resulting in severe hypoxia.

Hemodynamic instability after induction may be due to decreased venous return from compression of the superior vena cava, right ventricle, or pulmonary artery or from air trapping, hypoxic pulmonary vasoconstriction, or cardiac tamponade. Treatment consideration include:

• Immediate fluid resuscitation and repositioning to reduce mechanical compression
• Rapid escalation to ECMO may be required. There is a role for peripheral veno-arterial ECMO for patients with anterior mediastinal mass, but it may not be effective depending on the location of the tumor and the structures involved. It is vital to evaluate differential hypoxia caused by the anterior mediastinal mass compression on specific structures.

The authors remind us that thorough pre-anesthesia evaluation, risk stratification, multidisciplinary collaboration, and meticulous planning are the keys to achieving optimal outcomes for patients with AMMs undergoing anesthesia. For these patients, less is more to keep them safe, so this means the least-invasive procedures that do not require general anesthesia should be considered whenever possible, followed by anxiolysis or mild to moderate sedation with local or regional anesthesia and spontaneous ventilation. When general anesthesia is required, make sure you have a plan for escalation to rigid bronchoscopy, airway stenting, and ECMO. The authors leave us with this call to action:

“Adopting appropriate risk stratification systems, establishing institutional guidelines towards local care or transfer of care, and setting previously agreed guidelines across disciplines are critical for safer patient care.”

Have you taken care of a patient with an anterior mediastinal mass before? Are you preparing for an upcoming case? We hope that these considerations will help keep patients with anterior mediastinal mass safe during anesthesia care. If you have any questions or comments from today’s show, please email us at [email protected]. Please keep in mind that the information in this show is provided for informational purposes only and does not constitute medical or legal advice. We hope that you will visit APSF.org for detailed information and check out the show notes for links to all the topics we discussed today.

Until next time, stay vigilant so that no one shall be harmed by anesthesia care.

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