Mediastinal tumor resection

Mediastinal tumor resection

Anesthesia type	GETA
Airway	DLT vs SLT w/ bronchial blocker
Lines and access	large bore PIV x2, A line
Monitors	Standard, 5 lead ECG, A line
Primary anesthetic considerations
Preoperative	Airway may be compressed by mediastinal mass
Intraoperative	Lung isolation required in most cases
Postoperative	Epidural analgesia is recommended with open thoracotomy for postop analgesia
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Editor rating	Comprehensive
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Mediastinal tumors are characterized by their location in the mediastinum: anterior, posterior, middle. The common anterior mediastinal masses can be remembered by the "Terrible T's": thyroid (substernal goiters), thymoma, teratoma (germ cell tumors) and "terrible" lymphoma. Common masses of the middle mediastinal compartment include bronchogenic cysts, pericardial cysts, lymphomas. Common masses of the posterior compartment primarily consist of neurogenic tumors, esophageal tumors and lymphoma. The approach to resection depends on the tumor location and extent of invasion. Substernal goiters can often be removed from a superior approach from the neck. Tumors of the anterior compartment are typically handled via median sternotomy. Tumors of the middle and posterior compartment are approached best via lateral thoracotomy or VATS approaches.

Resection approaches also have to consider the invasion extent of the primary tumor and whether attached structures can be safely dissected away or sacrificed. Tumors with vascular invasion may require multidisciplinary approach with a cardiac surgeon and the use of cardiopulmonary bypass. In addition to posing tricky surgical considerations, large anterior mediastinal masses may also present significant anesthetic challenges. In particular, large bulky masses may compress the airway and induction of anesthesia may cause critical intrathoracic airway obstruction. Although rigid bronchoscopy may sometimes be able to bypass the obstruction and allow ventilation, often times the only safe method for ensuring ventilation on induction of anesthesia is preinduction peripheral VV-ECMO cannulation.

Preoperative management

Patient evaluation

System	Considerations
Neurologic	Patients with lung cancer may develop Lambert-Eaton myasthenic syndrome, quantitative monitoring of neuromuscular blockade is recommended.
Cardiovascular	Elderly patients may have comorbid CAD, preop testing to risk stratify is recommended if indicated by history. Tumors with invasion and compression of the great vessels and/or chambers of the heart may cause cardiovascular compromise with induction of anesthesia
Pulmonary	Bulky mediastinal lymphadenopathy may make airway management in the anesthetized patient precarious. Ensure that the pt can lie flat without significant airway compression. Patients treated with bleomycin should have FiO2 < 40% intraop to prevent hyperoxic lung injury.
Gastrointestinal	Bulky mediastinal lymphadenopathy can cause partial esophageal obstruction, increasing the risk of aspiration
Hematologic	Malignant processes may induce comorbid anemia
Endocrine	Depending on the exact pathology of the anterior mediastinal mass/lymphadenopathy, there may be underlying comorbid thyroid or paraneoplastic syndromes.

Labs and studies

• Preoperative labwork, cardiac studies, and imaging will vary amongst patient populations. As in all cases, much of the preoperative studies will be based on individual patient H&P
• At a minimum, all patients should have a preoperative hemoglobin and type and screen on file prior to case start
• in patients with a history of cardiac disease or low functional status, consider additional cardiac testing with ECG, echo/stress echo. Any reversible ischemia should prompt further cardiac consultation
• in patients with a history of pulmonary disease, consider further testing with PFTs, ABG and/or flow/volume loops.

Operating room setup

• Standard OR setup
• A-line
• Double lumen tube (left) vs bronchial blocker with SLT
• flexible bronchoscope for DLT placement vs bronchial blocker placement
• fluid warmer in case transfusion is needed
• forced air warmer

Patient preparation and premedication

• multimodal analgesic technique is recommended.
• thoracic epidural vs ESP block
• consider H2 antagonist and sodium citrate in patients with reflux or partial obstruction to esophagus

Regional and neuraxial techniques

• especially if an open thoracotomy approach is utilized, epidural placement for intraop/postop analgesia is recommended in patients without contraindications.
• ESP catheter placement can also be a viable option for postop analgesia

Intraoperative management

Monitoring and access

• standard ASA monitors
• 5 lead EKG
• invasive hemodynamic monitoring with arterial line
• 2 large bore PIV
• central access as indicated by history and physical and surgeon preference, though uncommon for this type of procedure

Induction and airway management

• patients with mediastinal disease with compression of the esophagus are often at high risk of aspiration, RSI induction with cricoid pressure in these patients is recommended
• Lung isolation is necessary, placement of a (left) double lumen tube is recommended though other techniques may be used.
• In patients with a difficult airway and high aspiration risk, intubation with a single lumen tube followed by tube exchange vs bronchial blocker can be a viable strategy
• It is highly recommended that the surgeon be in the room or immediately available at induction should rigid bronchoscopy or ECMO be necessary.
• if there is high suspicion that the mediastinal mass will critically compress the airway on induction (eg. critical tracheal/bronchial compression at rest, stridor, dyspnea, imaging with critical stenosis etc...) creating an emergency cannot-ventilate-cannot-intubate scenario that can neither be solved with surgical airway, discuss with primary surgeon about potential pre-induction VV-ECMO cannulation.

Positioning

Positioning will depend on the location of the mass and the approach taken (median sternotomy vs open thoracotomy vs VATS).

• resection via median sternotomy: typically supine
• resection via lateral thoracotomy or VATS: lateral decubitus vs supine

Maintenance and surgical considerations

• standard maintenance with volatile or intravenous anesthetics, or balanced technique. Avoid nitrous given one lung ventilation
• if epidural was placed preoperatively, bolus or continuous infusion of local anesthetic with or without additional epidural opiate can provide intraop analgesia. If epidural opiate loading dose is used to enhance analgesia, administer early during the surgery and at least 1h prior to end of case.
• Lung isolation will be necessary, communicate with surgeon should the patient not tolerate one lung ventilation
• In patients treated with bleomycin, ensure the FiO2 remains <40% to prevent hyperoxic lung injury

Emergence

• extubation is anticipated in most cases
• major fluid shifts may occur during surgery which may cause significant airway edema. If extubation is contraindicated, tube exchange to a single lumen tube should be performed prior to transport to ICU.

Postoperative management

Disposition

• PACU then step down surgical unit if extubated
• ICU disposition if postop mechanical ventilation is indicated

Pain management

• epidural postop analgesia with PCEA is preferred vs nerve block (ESP) catheters
• multimodal analgesia with opioids and/or NSAIDs

Potential complications

• major bleeding: tumor invading vascular structures can massive hemorrhage during dissection.
• chyle leak from thoracic duct injury: initially treated with bowel rest but may need duct ligation or embolization of the cisterna chyli
• recurrent laryngeal nerve/phrenic nerve injury
• SVT/afib
• thermal injury to membranous bronchus during dissection of subcarinal nodes
• DVT/PE: malignant disease will predispose patients to VTE.
• pulmonary complications (atelectasis, aspiration, pneumonia, pneumothorax)