Anesthetic considerations in patients with mediastinal tumors

R1 顏廷珊

History

Name: 鄭 * 曦 Gender: female Age: 4 y/o Date of birth: 2000/08/30 G1P1, full term, BBW: 2750g

2002/09: decreased activity and intermittent noisy respiratory sound presented at MKMH: chest CT revealed a large heterogeneous mass over right lung field with much pleural effusion.

She was transferred to our hospital: Saturation was around 94~96%. CXR showed whiteout over right lung field with trachea deviated to left side

Tumor biopsy with port-A insertion was done on 2002/09/27 with mildly improved respiratory distress. Pathology of the mediastinal mass reported sarcoma, unclassified.

Chemotherapy was planned, but family refused. She was then AAD on 10/08 under respiratory distress (SpO2 sound 90-95% with tachypnea RR around 35/min)

Cough persisted after discharge and some traditional medication had prescribed. Poor activity, poor appetite, dyspnea, orthopnea, and much oral secretions developed

She was then brought to our ER on 10/28 where chest CT revealed huge mediastinal mass occupying the whole right lung field with mediastinal shift (main airway and heart was compressed)

Due to high risk of cardiopulmonary compromise, emergent-debulking surgery (nearly total removal) was done in the night of 2002/10/28.

The right lung expanded and heart, trachea returned to normal position after operation.

The pathological diagnosis was infantile fibrosarcoma. She was discharged on 11/18 under stable clinical condition.

Follow up chest CT (2002.12) showed extensive mass lesions within the right upper, lower lung fields, right thoracic cage. Under the impression of tumor recurrence, adjuvant chemotherapy was started.

Totally 4 courses of VAC were given.

CT on 2003/07/02 showed a lobulated mass lesion at lateral aspect of right upper thorax with bone destruction of lateral aspect of right 2nd rib, which showed increased size, compared with previous CT study in 2003.4. Right lower posterior pleural thickening with enlarging focal nodular lesion was also noticed.

The surgery was performed smoothly on 2003/07/04. A tumor mass of 3x1 cm was excised from the 5th rib area. A patch of tumor in the inner chest wall surface extending from the subclavian area to 5th rib was also removed. Furthermore, a 0.2x0.2 cm tumor was removed from the inferior posterior part of her chest wall. There was also one tumor removed from dorsal side of her scapula.

She then received VIP(vp-16 + ifosfomide + cisplatin) on 7/17-24

Compared with pre-op films, two new (enlarged) lesions were seen on right posterior pleura, 1cm below carina and around right inferior pulmonary trunk level.

Disease progression was highly suspected. In the surgical pathologic conference on 7/22, pathologist, pediatric surgeon and radiologist revised the diagnosis as malignant peripheral nerve sheath tumor (MPNST) based on immunocytochemical stain.

After searching the literature about MPNST. This tumor is generally considered to be chemo-resistent. What seems to improve the diagnosis is complete surgical resection and adjuvant radiation therapy

Her family hesitate about radiotherapy. She continued to receive several courses of chemotherapy during 2003/08-2003/10.

2003/11: A 1x1 cm firm mass over left scapular region was found

2003/12: a rapid growing mass above the previous one appeared. It grew to 6x6 cm in 1 month with pain and itchness

2004/01: she always lied on the bed with right side down and unwilling to sit or stand , fever up to 38.2, Due to poor activity and r/o airway obstruction, she is admitted today for further evaluation

Chest CT was done on 1/20 that revealed huge tumor mass involved right side hemithorax, scapula, shoulder. Right lung almost total collapsed and mediastinum was compressed to left side. Due to mass effect of tumor and its rapid growing, pediatric durgeon VS. 許文明 was consulted and emergent debulking surgery was done in the night of 1/20.

Extubation was done on 1/26 and she was transferred to general ward on 1/27.

Reevaluation of tumor mass of CT on 2/3 showed heterogeneous mass lesion occupy in the right side upper thorax with extension to the thoracic cage and right side axillary portion with surrounding bone destruction. This tumor also invaded into the right side scapullar region and result in partial atelectasis of the right lung.

Due to the rapid growing and ineffective result of chemotherapy, radiotherapeutics was consulted for treatment plan.

Continue chemotherapy Fever tumor fever was more likely

Follow up CT and MRI showed bulky mass lesion at the right lower neck, right chest wall, right thoracic cavity  on 2003/02-03

CVS and chest surgeons were consulted for the possibility of compromising of great vessels, trachea, esophagus, and heart.

Progressive dyspnea was note on 2004/04 Episodes of desaturation to SpO2 around 80

% noted since 2004/04/09

She was transferred to PICU on 2003/04/11 due to impending respiratory failure.

Emergent debuking surgery was arranged on 2004/04/12.

Induction with ketamine and sevoflurane Intubation with 6.0 without cuff fixed at 16 cm Paralysis with Esmeron with controlled positive ventilation Supine position CO2 retention >110 mmHg was noted, peak airway pressure was hi

gh ( > 40 cm H2O) Fiberscope was performed: external compression was noted around

16-17cm The endotracheal tube was then fixed at 20cm for one lung ventilati

on CO2 was washed out smoothly and quickly Then the endotracheal tube was fixed at 18cm just above the carina Maintenance was uneventfulh

Endotracheal tube was inplace with ventilator low setting in PICU

PS surgery for extrathoracic debulking was planned on 4/16.

After induction with pentothal, nimbex, and fentanyl, CO2 retention (around 70-80 mmHg) with high peak airway pressure was noted.

Fiberscope was performed: no significant obstruction

Desaturation to SpO2 around 70% was noted after left decubitus positioning

Left breathing sound: clear, chest wall expansion(+)

100% O2 supple, PEEP 5 cm H2O, change position to supine right decubitus: no improve

Spontaneous breathing SpO2 returned to 100%

The surgery was DC. Extubation was performed on 4/18 by herself.

After extubation,she still need some O2 supplement.

Discussion

1. What is MPNST?

2. Anesthetic management of mediastinum tumor

3. What happened to this patient?

Malignant peripheral nerve sheath tumor (MPNST) Derived from Schwann cells or pluripotent cells of th

e neural crest The most common malignant mesenchymal tumors

of soft tissue 4% of patients with neurofibromatosis type I develop

ed MPSNT General population: 0.001% Classification based on gross anatomy: spinal root,

peripheral nerve, nerve plexus, no nerve of origin

Most frequent initial s/s: painless mass Diagnosis is usually delayed ( 5.5 months) MRI, ti

ssue proved Wide surgical excision is the treatment of choice an

d prolongs survival. Adjuvant or neoadjuvant radiation therapy decrease

d the hazard of death of disease. Chemotherapy is of unproven benefit: more likely to

have tumor characteristics predictive of an unfavorable outcome.

Local recurrence rate following gross total resection: 32-65%

Anesthetic consideration

Compression of the tracheobronchial tree Compression of the pulmonary artery and he

art Superior vena cava syndrome

Compression of the tracheobronchial tree Pathophysiology

1. Anterosuperior mediastinum: thymus, lower trachea, upper esophagus, the arch of aorta and branches, SVC, azygos veins

2. Adults: thymic neoplasms, lymphoma, germ-cell tumor

3. Children: neurogenic tumors, germ-cell tumors

Obstruction of major airways by a tumor is usually life-threatening because the obstruction usually occurs around the bifurcation of the tracheabronchial tree and is therefore distal to the endotracheal tube.

It may be that loss of chest wall tone and the distending forces of active inspiration after administration of muscle relaxants release extrinsic support of a critically narrowed airway

intubation in the presence of distortion or compression of the trachea may cause complete obstruction if the orifice of the tube impinges on the tracheal wall or if the lumen of the tube is occluded where it passes a narrowed section or turns a sharp angle

Risks of GA

lung volume is reduced to as little as 500–1500 ml under general anaesthesia;

relaxation of bronchial smooth muscle leads to greater compressibility of the airway from the overlying mass;

the loss of spontaneous diaphragmatic movement with paralysis induced by muscle relaxants reduces the normal transpleural pressure gradient which dilates the airway. This decreases the calibre of the airways and enhances the effect of extrinsic compression.

Pre-op evaluation

1. Clinical S/S

2. CXR

3. CT

4. Pulmonary function test

Clinical S/S: cough, DOE, orthopnea, stridor, cyanosis, wheeze, ronchi

Even asymptomatic patents have developed life-threatening complications at induction of anesthesia.

CXR

PA position: measurement of the trachea diameter at the level of the clavicals, may over estimate though

Lateral view: show the degree of compression of the trachea in an AP direction

CT

Identify the location of the mass Delineate its margins Define its relationship to adjacent structures Determine the extent of tracheal or vascular

compression

CT

Cross-section area A1: narrowest area; A2: an area without extrinsic co

mpression or endoluminal involvement A =π* d1/2 * d2/2 Tracheal compression (%)= 100- (A1/A2 * 100) Tracheal compression > 50%: high rate of total airw

ay obstruction during GA, sevenfold increase in the risk of post-op respiratory complication

GA should be avoided in children with less than 66% (50%?)of normal tracheal area

Pulmonary function test

FEV1, FVC, PEFR, flow volume curve Obstructive: FEV1<80%, FEV1/FVC <70% Restrictive: TLC < 85%, FVC < 80%,

FEV1/FVC > 70%

PEFR <40% : > 10-fold increase in risk of periop complication

A combination of obstructive and restrictive patterns high rate of post-op respiratory complication

Flow volume loop

Supine, upright, and lateral position Variable extrathoracic obstruction: expiration i

s preserved; inspiration impaired Variable intrathoracic obstruction: expiration i

mpaired; inspiration is preserved Fixed: both impaired Rarely useful; not offer any additive benefit in

predicting periop complications

Peri-op management

In pediatric patients: volatile agent induction is usually the technique of choice

In adult: awake fiberotic technique with topical anesthes

Spontaneous breathing, avoid muscle relaxants

Change positions rapidly Rigid ventilating bronchoscope Cardiopulmonary bypass

Patients should be allowed to breath spontaneously

In paralyzed patients:-Positive pressure ventilation induced dynamic hyperinflation high transbronchial pressure worsen obstruction decrease expiratory flow (manual compression of chest wall )-large changes in intrathoracic pressure promote collapse of a weakened tracheobronchial tree

Compression of the pulmonary artery and heart Very rare: the pulmonary trunk is more or less protected by the a

ortic arch and trachealcronchial tree (Miller) More common than realized:

1. In the supine position, the right ventricular outflow tract is the most superior cardiac structure 2. the right heart is a low-pressure chamber, and is more sensitive to compression than the high-pressure ascending aorta. The right heart usually can compensate for moderate increases in pulmonary afterload. 3. Adverse position, induction of anesthesia, hypovolemia, and reduced cardiac contractility, however, may attenuate compensatory mechanisms.

Clinical S/S are not apparent; mimic tracheal or bronchial obstruction

mediastinal CT or MR imaging and ECG, should identify at-risk patients.

Patients who develop syncope during Valsalva maneuver are believed to be particularly at risk, because this situation suggests significant vascular encroachment

Peri-op management Patients with an anterior mediastinal mass may de

velop severe hemodynamic compromise caused by compression of the heart and great vessels after induction of anesthesia, institution of positive pressure ventilation, or supine positioning.

Positive pressure ventilation can cause dynamic hyperinflation autopositive end-expiratory pressure (auto-PEEP) because of expiratory gas flow obstruction.

With sufficient elevation of intrathoracic pressure, the gradient for venous return is reduced, and right ventricular pressures are reduced, worsening the extent of vascular obstruction.

Intravascular volume loading Prompt use of inotropics and vasoconstrictors to mai

ntain cardiac output Be acutely aware of the position of the mass in relati

on to the cardiovascular structures because urgent repositioning of the patient may be required to relieve severe hypotension

Maintain venous return Maintain spontaneous breathing Cardiopulmonary bypass ECMO

Superior vena cava syndrome

Mechanically obstruction of the SVC Edema of the head, neck, and upper

extremities Respiratory S/S, epidural vein enlargement Catheterization on lower extremities

What happened to this patient?

CO2 retention, expiration impaired - airway compression- paralyzed with positive pressure ventilation

High airway pressure Desaturation

- inadequate ventilation: positioning? - increased shunting: inhalation anesthetics reduced hypoxic pulmonary vasoconstriction - lung collapse: high airway pressure

Thereafter …

The patient was extubated by herself on 4/18 evening

Still need O2 support She was transferred to general ward for ongo

ing chemotherapy on 4/19 She was transferred back to ICU on 4/24 due

to impending respiratory failure

We were consulted for intubation on 4/24 night

O2 mask, SpO2 100%, respiratory with effort, right decubetus position

Ketamine 20mg was given, SCC 10 mg Intubated with 5.5 with cuff fixed at 18cm Ventilator: low setting She is waiting for… ( further treatment???)

References

Anesthesia, 5th edition, Ronald D. Miller ANESTHESIA FOR PATIENTS WITH A MEDIASTINAL MASS,

Anesthesiology Clinics of North America,Volume 19 • Number 3 • September 2001

Surgical rescue for life-threatening hypoxemia caused by a mediastinal tumor, Ann Thorac Surg, 1999, 68:2324-6

Anterior mediastinal masses: an anesthetic challenge, anesthesia, 1999, 54:670-682

General anesthesia prior to treatment of anterior mediastinal masses in pediatric cancer patients. Anesthesiology 72:991-995, 1990

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