Management of Post-operative Anterior Mediastinal Mass Patients: A Review

INTRODUCTION

The mediastinum is considered to be the most bothered region of the human body because it contains the vital organs. The patients with anterior mediastinal mass (AMM) often present the anesthesiologist and intensive care unit (ICU) physician with a formidable challenge during their perioperative course. Bleeding, severe respiratory as well as cardiovascular complications, including inability to resuscitate, can stem during the post-operative period, leading to a huge burden on the management team. This review narrates the management of these high-risk patients in the ICU during their post-surgical period.

A BRIEF ABOUT AMM

Knowledge regarding the type of AMM is important because of their heterogeneous pathology that may give rise to compression of the surrounding structure and their sequel. They may be benign or malignant and arise from the thymus, lymph node, and nearby structures. They may be teratoma, lymphoma, thymoma, cystic hygroma, and simple cyst.^[1] Post-operative care not only depends upon the extent of surgery but also on the size, histological type, and physiological effect of the mass. There are reports describing fatal cardiorespiratory jeopardy during the post-extubation period.^[2-4] Extension of other tumors to the anterior mediastinum is not a part of this review.

POST-OPERATIVE CARE MANAGEMENT IN ICU

The post-operative patients are divided into three groups depending upon their symptoms and radiological evidence of airway compromise when post-operative care is concerned. The low- risk group has no or mild symptoms without any airway compromise. Patients with some postural symptoms and <50% airway compression constitute the moderate risk group; whereas those with >50% airway compression, along with stridor and cyanosis, belong to the severe risk group. Intense post-operative care in ICU is needed only for patients with a large mass who undergo a prolonged surgery or cardiopulmonary bypass (CPB), have preoperative systemic manifestations, or a recipient of preoperative chemotherapy or radiotherapy.^[3,4]

Resection or removal of surrounding anatomical structures, for example, pericardium, lung, or part of the chest wall, is needed in some cases; whereas reconstruction of vascular structures, for example, superior vena cava may be required in others. These patients need vigilant monitoring and intense care.^[4-7]

The post-operative care is to be started from the preoperative period, which includes: Cessation of smoking 6 weeks before surgery, bronchial hygiene and physiotherapy, psychotherapy, education regarding postextubation breathing and coughing exercises, as well as exercises to prevent/reduce the incidence of deep vein thrombosis (DVT).^[7,8]

Prior information regarding patients’ intraoperative situation and estimated arrival time in ICU should be given to the ICU team. A multidisciplinary team (anesthesiologist, surgeon, intensivist, psychiatrist, team of physiotherapy and nursing) approach is best for patients with complex diseases. Sudden jeopardy is not uncommon, which can be in the form of hemorrhage, exacerbation of symptoms of preexisting myasthenia gravis, or chemotherapy-related complications. Altered hemodynamics, rapid breathing, and acute change in the level of consciousness are the early warning signs that need urgent attention.^[9,10] The following paragraphs narrate the care as well as brief management of common postoperative complications [Table 1] following AMM surgery.

RESPIRATORY COMPLICATIONS AND CARE

The low-risk group patients have early extubation and minimal hemodynamic monitoring for the initial 24 h postoperatively. More aggressive cardiorespiratory monitoring is required for patients belongs to the moderate or severe risk group. All the measures for cardiopulmonary resuscitation should be in hand for patients who have undergone diagnostic excision because of their propensity for the development of sudden cardiorespiratory collapse.^[11-13]

Patients with prior tracheal compression may undergo video-assisted diagnostic biopsy under general anesthesia and arrive in the ICU with an endotracheal tube (ETT) in situ. Till the decision of a final procedure, a satisfactory level of sedation, analgesia, and muscle relaxation, along with unbending attention, is important in these patients for the prevention of accidental endotracheal extubation. Suitable size of ETT and rigid bronchoscope set must be there within easy reach. It is better to replace the ETT over a tube exchanger if at all needed. Rescue position (e.g., sitting, upright, lateral decubitus, prone) improves symptoms of pulmonary compromise. Volume expansion, vasopressor/inotrope may be required as severe hemodynamic compromise may occur during this period. Emergency sternotomy and CPB or extracorporeal membrane oxygenation is required to shift the mass from the compressed structures.

Patients may develop pneumonia or atelectasis within 48 h postoperatively. Pulmonary damage is common in those on bleomycin therapy. Keep the fraction of inspired oxygen (FiO₂) as low as possible to maintain reasonable arterial saturation, as high FiO₂ is detrimental in these patients.^[10,11] Postoperative airway edema or tracheobronchial tree hemorrhage can lead to airway obstruction. This can be manifested as a decrease in oxygen saturation (SaO₂), stridor, and other signs of respiratory distress in a spontaneously breathing patient. The patient on a ventilator may show an acute increase in airway pressure and ETT bleeding. An aspiration volume of >200 mL/h warrants urgent intubation. Once such a scenario happens, place the patient in a dependent position to protect the non-bleeding lung from spillage. Bronchoscopy/ computed tomography (CT) are the diagnostic aids. The bleeding site is managed by different methods, e.g., surgical control or embolization of bleeding vessels, endobronchial ablation/balloon tamponade of the bleeding site/ radiotherapy to the residual tumor.^[12,13] Optimal ventilator settings for these patients are still a question. In this scenario, retain the endobronchial balloon in an inflated position for 24 h period before further intervention. In case of non availability lung isolation techniques, selective intubation of the normal lung is to be done by a single lumen ETT until subsequent intervention. In difficult cases, a surgical airway can be considered. Needle aspiration or surgical clamping can decompress neck hematomas.^[12,13]

Long-standing cases may develop tracheomalacia, and a larger-diameter ETT or controlled tracheal suspension can overcome this problem.^[14] The causes of pneumothorax are many, and the cause due to tumor pleural infiltration is severe. Clinical suspicion and immediate decompression can save a patient from the sequel of tension pneumothorax.^[11]

Bronchopleural fistula can occur as early as the first day and as late as >30 days postoperatively.^[15,16] The diagnosis is usually done by clinical suspicion/chest X-ray/CT/single photon emission CT. The management of these patients varies from conservative to sclerotherapy or surgical, depending upon the size and cause of the fistula.

Patients who have undergone surgery for an extensive malignant mass or have secondary infection may develop pleural effusion (PE) during their ICU stay. Heart failure, thromboembolism, hypoalbuminemia, or the toxic effect of chemo or radiotherapy are the possible causes.^[16] Intrathoracic bleeding occurs in the presence of extensive mediastinal adhesion. Chest X-ray and ultrasound are diagnostic. Management varies from medical to needle drainage and surgical.

Major resection may lead to mediastinal emphysema. Chest X-ray and/CT are the diagnostic aids, and the usual mode of management is insertion of a chest tube. Iatrogenic damage to lung parenchyma during surgery, barotrauma related to ventilator support, or coexisting emphysema can give rise to air leak. Intervention is needed if it continues for more than 5 days.^[15-17] Early extubation reduces this complication, and early intervention in a large leak is helpful.

Bronchospasm, atelectasis, infectious mediastinitis, and respiratory failure are other possibilities, especially in malignant masses with prior radio or chemotherapy. The diagnosis and management is general as that of any other surgical patients.

CARDIOVASCULAR ISSUES AND CARE

Cardiovascular instability is a consequence of the compressive effect of a large mass or massive resection and reconstruction of cardiac structures during tumor removal, apart from hypothermia, massive bleeding, pain, or excessive use of inotropes/vasodilators.

Management includes correction of precipitating factors and unstable hemodynamics.^[18,19] Extensive resection of the pericardium may cause cardiac herniation. Quick reduction of the herniated cardia prevents the development of ventricular outflow tract obstruction and its consequences.^[20]

Arrhythmias are not uncommon, and the most common one is atrial fibrillation. Apart from the usual risk factors (e.g., hypoxia, hypercarbia, acidosis, pain), it can also be patient-related (preexisting cardiac problem, older age, decreased pulmonary reserve), surgery-related (anesthetic agent, extensive manipulation of cardiac structures, intrapericardial pneumonectomy, etc.) or treatment-related (e.g., prior radiotherapy to the chest or ongoing cardiotoxic chemotherapy). Treatment of the underlying cause is important before pharmacotherapy.

Persistent hypoxia during the post-operative period gives rise to the development of right-to-left shunt in a patient with a patent foramen ovale (PFO). The shunt fraction increases if there is a decrease in right ventricular (RV) compliance (e.g., during manipulation of right pulmonary parenchyma, positive pressure ventilation, chronic obstructive pulmonary disease, or pulmonary thromboembolism [PTE]). Echocardiography in combination with arterial blood gas analysis gives an immediate bedside diagnosis. Surgical closure or trans-catheter occlusion of PFO in the cardiac catheterization laboratory can improve the situation.

Extensive surgery, prolonged CPB time, and manipulation of the heart may give rise to ventricular dysfunction and low cardiac output syndrome in the first 48 h post operatively. Echocardiography in combination with hemodynamic trend analysis over a time period is diagnostic. Management is mostly medical. A patient who does not show improvement in mean arterial pressure and mixed venous oxygen saturation after volume therapy needs an afterload-reducing agent to improve cardiac output.^[21] In refractory cases, mechanical circulatory support needs to be considered.

Lung damage during mass removal, pulmonary resection, or volume overload may give rise to pulmonary edema. It is essential to differentiate cardiogenic pulmonary edema. Cardiac tamponade and chylothorax are some other complications that need to be addressed early. Chylothorax usually occurs due to direct injury or incomplete ligation of lymphatic channels during mediastinal lymph node resection. The usual time of onset is from 2 to 4 weeks postoperatively, and depending upon the amount and rate of chyle loss, it varies from mild-to-severe form.^[22]

Post-operative hypercoagulable state, especially in a malignant mass, may put the patient at risk of thromboembolism, for example, DVT/PTE.^[23] This can be prevented by the application of elastic stockings, pneumatic compression devices, and early ambulation in most of the cases. Some of the patients may need low molecular weight heparin. Unless it is contraindicated, heparin at a dose of 5000 IU subcutaneously twice daily can be given from the preoperative period till the time of discharge. Administration of a therapeutic dose of heparin and use of an inferior venacaval filter is essential if signs of DVT are present. A direct anticoagulant can be given. PTE can be diagnosed by a high index of suspicion and visualization of thrombus in PA or other associated changes due to PTE, for example, dilation and strain pattern in RV. Pulmonary angiography is diagnostic in difficult cases. Thrombolysis and systemic anticoagulation are the initial management aids. Surgical or catheter embelectomy is done in refractory cases.^[15]

Bleeding and coagulopathy are mainly due to surgical issues. A bleeding patient without any surgical cause is managed with blood and blood products depending on the coagulation status of the patient. Surgical intervention is needed if chest tube drainage exceeds more than 200 mL/h in 4 h or 1000 mL in 1 h. A blockage of the chest drain is indicated by low hematocrit and a radio-opaque surgical site in a hemodynamically unstable patient.^[24] Fresh-frozen plasma and Vitamin K are used to correct medication-related bleeding. A normal chest X-ray does not indicate application of suction and chest drains to be removed within 24 h. Keep the drain for a longer period if there is persistent bleeding. Apply Heimilch valve container for early ambulation if there is expansion of the lung parenchyma.

Phrenic nerve palsy may occur, which leads to difficult weaning from the ventilator. X-ray chest, ultrasound, and fluoroscopy are the diagnostic aids. Surgical plication of the affected diaphragm is the answer. Aspiration can occur in the case of recurrent laryngeal nerve (RLN) palsy. Visualization of sluggish motion of the affected vocal cord by indirect laryngoscopy is diagnostic. This condition is usually temporary, and regular physiotherapy can prevent aspiration. Non-respondent cases need laryngoplasty.^[12,24]

PAIN MANAGEMENT

The control of post-operative pain is largely challenging, and the consequence of inadequate pain control is well known. The overall management of pain is enhanced by patient education concerning certain aspects of pain management, for example, patient control analgesia, risk of pain medication and addiction due to pain medication, etc. Preemptive as well as multimodal pain management followed by most therapists, though various pain management protocols are available. Pain management methods vary depending on the site and extent of surgery.^[25-27]

SOME DREADED COMPLICATIONS AFTER TRACHEAL RECONSTRUCTION

Most of the complications following tracheal reconstruction have a grave prognosis and need urgent attention. It ranges from minimal glottis edema to RLN palsy, anastomotic separation, and formation of tracheoesophageal or tracheainnominate fistula. Some degree of airway obstruction occurs due to the development of granulation tissue around the anastomotic site. The patient may develop stridor that can be relieved with debridement and triamcinolone. The presence of airway edema often makes orotracheal intubation and airway stabilization difficult. Distal airway cannulation from an anastomotic site may save the patient. A clue to the diagnosis of air leak can be made from a CT chest and neck. Leaks larger than 1 cm require neck exploration and an airway appliance to overcome the jeopardy.^[40,41] In the presence of significant laryngeal edema, place a tracheostomy tube through the leak site, and surgical repair is done once the edema is reduced. Neck in flexed position, voice rest, antibiotic therapy, and at times, hyperbaric oxygen are required for wound healing.

Trachea-innominate fistula can be massively fatal. Though sentinel bleed is the early sign, the classic presentation is massive hemoptysis leading to cardiorespiratory collapse. A small bleed can be temporarily sealed by emergent ETT cuff inflation. Glottis edema is usual with handling of the larynx, and the patients are improved with voice rest, steroids, diuretics, and epinephrine nebulization. Some non-respondent patients need tracheostomy. Swallowing dysfunction may be transient in the first 24–48 h, but needs care to prevent aspiration.

SOME UNCOMMON MASSES NEED SPECIAL CARE

Post-operative elective mechanical ventilation is required in 40% patients with a thymic mass. Thymic carcinoids are usually associated with multiple endocrine neoplasia or Cushing’s syndrome and thus need further care. Patients with prior radiotherapy or bleomycin therapy mostly have pre-existing pulmonary injury and adhesion of mediastinal structures, thus need to be taken thoughtfully and seriously. In these patients, the FiO₂ is to be kept as low as possible but compatible with the best possible PO₂ to meet metabolic demand without causing further pulmonary damage.

MANAGEMENT OF FLUID AND ELECTROLYTES

Judicious fluid administration should be encouraged postoperatively to prevent overhydration problems. In the absence of any major loss 1–2 mL/kg/h fluid is adequate enough. Keep the positive fluid balance as low as 1.5 L in an adult to prevent pulmonary injury. Silent hypovolemia leading to AKI, along with impaired tissue oxygen delivery, may complicate the issues with restricted fluid therapy. Consider inotrope or vasopressor support if signs of hypoperfusion persist in spite of adequate volume supplementation and in the absence of major loss.

POST-OPERATIVE NUTRITION

It is an essential and significant component of care for patients who have prolonged ICU stay and recovery. Early oral feeding is safe and improves wound healing. Post-surgery, metabolic alterations lead to increased energy expenditure, enhance catabolism, and reduce synthesis of protein as well as extracellular fluid shift. The subsequent result is poor wound healing, impaired immunity, and decrease in respiratory muscle strength as well as organ dysfunction. Therefore, it is always important to identify and start the supplement preoperatively for at-risk patients. Special emphasis should be given to malignant AMM. Mechanically ventilated patients develop a continuous reduction in muscle mass if nutritional supplementation is not done. Monitoring the patient’s food intake, oral supplements, or enteral/parenteral nutrition may be needed to guide both energy and protein requirements. Among several available models, indirect calorimetry is one of the best-followed methods for measurement of resting metabolic rate and resting energy expenditure (REE) in these post-surgical patients. Start the supplemental nutrition in the following situations:

1. If the patient is having preoperative malnutrition and cannot take oral feed for more than 5 days postoperatively

2. Have low oral intake (<50% of the recommended intake for more than 7 days).

3. Start both oral and enteral supplements as soon as possible if oral calorie intake is <50% of the requirement or >7 days,

4. Start parenteral nutrition when oral and enteral calorie intake is <50% for a week.

In all nutrition therapy, the deleterious consequences of overfeeding need to be remembered.

POST-OPERATIVE INFECTION

The usual duration of antimicrobial therapy is 48–72 h postoperatively in benign and uncomplicated small masses. The protocol for post-operative antimicrobial and antifungal therapy depends upon the histology and size of the mass, extensiveness of surgery, the immune status of the patients, prior chemotherapy, and many other factors. The benefits versus toxicities of all patients need to be weighed against their safety and efficacy.^[42] For example, patients on preoperative chemotherapy have a greater benefit from fluoroquinolone prophylaxis than quinolones when Gram-negative bacterial infection is a concern.

PHYSIOTHERAPY

The usual components are: Chest percussion, coughing exercise, incentive spirometry, and maintenance of bronchial hygiene. It is always better to start physiotherapy from the preoperative period. Aspiration prevention is of paramount importance as it may result in sepsis and multi-organ dysfunction. Keep the patient nil per oral if they are prone to aspiration. Start nasogastric feeding if required. Allow oral feed only if the patient is completely awake and able to sit up. Supplement diuretics to decrease body water content, and thereby improve pulmonary function and early mobility.

RECENT ADVANCES AND FUTURE PROSPECTIVE

In the recent era, the post-operative outcome is more favorable due to the advancement in robot-assisted thoracic surgery and single-port video-assisted technologies. Even large complex AMM and those that have pleural or pericardial infiltrations, reduce the need for open sternotomy and thus related complications. At the same point, improvement in diagnostic modalities such as positron emission tomography with CT and magnetic resonance imaging; endobronchial and endoscopic ultrasound guided techniques along with multidisciplinary care have made the post-operative management and outcome of complex AMM much easier. Anesthesia management by non-intubated techniques and significant expansion of regional anesthesia techniques are a bonus for these patients. These modern approaches not only bring less trauma to the chest wall but also lead to shorter duration of hospital stay, better quality of life, and reduction of cost. The role of artificial intelligence technology (AI) in patient management is coming up in a big way. Remote patient monitoring and wearable devices can track patient vital signs, allowing AI to detect subtle physiological changes and send alerts for early intervention. It also helps to tailor pain management protocols and various physiotherapies to individual patient needs, thus improving recovery.^[43-47]

CONCLUSION

The post-operative course of AMM surgery may not be simple at times. Sudden cardiorespiratory collapse can occur at any point of care due to several reasons. Post-operative issues can vary from nil to several fatal complications. Implementation of protocols, a vigilant team, identification of early warning signs and symptoms improve the quality as well as the appropriate level of care. A patient as well as caregiver’s education facilitates the overall outcome to a significant extent.