1. Cardiovascular and Airway considerations in Mediastinal mass during Thoracic surgery
Dr.Sandeep Kumar Kar
Department of Cardiac Anaesthesiology IPGME & R, Kolkata
SUNDAY CTVAC 2014

2. Cardiovascular and Airway considerations in Mediastinal mass during Thoracic surgery
In 1975 Bitter1 described a case of respiratory obstruction associated with induction of general anesthesia in a patient with mediastinal Hodgkin’s disease.
One of the first described reports which drew the attention of the anaesthesiologists towards the probability of unexpected sudden collapse of the patients with mediastinal mass posted for elective surgery.

3. Mortality trends in surgery for mediastinal procedure in UK….
Total
Deaths %
Thymectomy for thymoma
159 1
0.6
193
0.5
181 2
Thymectomy for myasthenia gravis 56
0.0 48 57
Throidectomy 66
1.5 77
Resection of other mediastinal mass/tumour
210
1.0
198 3
191
Mediastinoscopy/ mediastinotomy
2858 19
0.7
2465 9
0.4
2240 6
Other mediastinal procedures
104 5
4.8
155
3.2
169 17
VATS- Resection of mediastinal mass/ tumour 90
126
129
VATS-Other mediastinal procedures
128 4
3.1
118
1.7
140

4. Review of Anatomy
.Described by the classic model and Shields’ model. . According to classic model3, the mediastinum is divided into four compartments: superior, anterior, middle, and posterior. Anterior and superior compartments are continuous, so combined to form antero-superior compartment.

5. Review of Anatomy
In 1972 Shields described an alternate model consisting of three-compartment:
Anterior compartment
Middle (or visceral) compartment
Posterior compartment (paraventral sulcus).
All three compartments are bounded inferiorly by the diaphragm, laterally by the pleural space, and superiorly by the thoracic inlet. The anterior compartment is bounded anteriorly by the sternum and posteriorly by the great vessels and pericardium.

6. Classic Model and Shields’ Model.

7. Components of Mediastinal Compartments as Proposed by Shields
Anterior
Thymus
Internal thoracic vessels
Internal thoracic lymph nodes
Fat and connective tissue
Visceral (middle)
Pericardium/heart
Great vessels
Trachea
Proximal right and left mainstem bronchi
Esophagus
Phrenic nerve
Thoracic duct
Proximal azygos vein
lymph nodes
Fat and connective tissue
Paravertebral (posterior)
Sympathetic chain
Proximal intercostal nerve, artery, and vein
Posterior paraesophageal lymph nodes
Intercostal lymph nodes

8. Classification of Anterior Mediastinal mass:
Lymphoma most common in pediatric age group.
Thymoma most common in adults.

9. Classification of Anterior Mediastinal mass
Neoplastic
Thyroid
Substernal goitre
Ectopic thyroid tissue
Thymus
Thymic hyperplasia
Thymoma
Thymic carcinoma
Thymic carcinoid
Thymic cyst
Thymolipoma
Teratoma
Mature
Immature
With malignant component
Germ cell tumors
Seminoma
Yolk sac tumours
Embyonal Carcinoma
Choriocarcinoma
Lymphoma
Hodgkin’s
Non-hodgkin’s
Ectopic parathyroid with adenoma
Lipoma/ Liposarcfoma
Fibroma/ Fibrosarcoma
Infectious
Acute descending necrotizing mediastinitis- Bacterial
Subacute-
Fungal
Mycobacterial
Histoplasma
Actinomycosis
Vascular
Aneurysm of the aortic arch with projection in the anterior mediastinum
Innominate vein aneurysm
Superior vena cava aneurysm
Dilation of the superior vena cava (with anomalous pulmonary venous return
Persistent left superior vena cava

10. Clinical presentation: can be varied!
Lymphomas may present with fever and weight loss.
Symptoms may appear due to compressive effect or malignant involvement of nearby structures.
Severity of symptoms depends on: size, site, consistency, nature, compressed structures etc.
Tracheal compression may manifest as cough, stridor, dyspnoea, orthopnoea, postural dyspnoea, cyanosis, hoarseness or recurrent respiratory tract infections.

11. Clinical presentation:
Tracheal compression may manifest as cough, stridor, dyspnoea, orthopnoea, postural dyspnoea, cyanosis, hoarseness or recurrent respiratory tract infections.
Compression of heart may result in dysrrhythmia, cyanosis or syncope.
Compression or malignant involvement of sympathetic chain may manifest as Horner’s syndrome (ptosis, miosis, anhydrosis, apparent enopthalmos, absence of pupillary dilatation on shading the eye and abolition of ciliospinal reflex)7.

12. SVC Obstruction:?
SVC obstruction characterised by, engorgement of the veins of the neck, right upper arm, chest wall and oedema of neck, head and upper arm. These cases may be associated with malignancy .
SVC cannulation may not be possible.
A course of preoperative chemotherapy and radiotherapy followed by femorofemoral bypass from beginning of surgery may be an attractive option.

13. Grading of symptoms is very important
Gradation of symptoms to mild, moderate or severe depends on patients’ tolerance to supine position.
Patients with severe symptoms will not voluntarily lie supine even for a short duration
A. Asymptomatic
B.Mild: Can lie supine with some cough/pressure sensation
C.Moderate: Can lie supine for short periods but not indefinitely
D. Severe: Cannot tolerate supine position.

14. Anesthetic management problems:

15. Infant with Mediastinal mass :Anaesthesiologist's Nightmare
Demarcation between the mediastinal compartments are arbitrary and a space occupying lesion from one compartment may easily compress the structures of other compartment.
More seen in children because of more incidence of neurogenic tumour.

16. The Real Reason: Small thoracic cavity size
More compressible cartilaginous structure of the airway
Reduced cardiopulmonary reserve small FRC
Difficulty in obtaining a history of positional symptoms in children
Mortality is higher in children

17. Respiratory complications during Anesthesia induction in a patient with mediastinal mass?
Reduction of lung volume with commencement of general anesthesia cause decrease in tracheobronchial diameter.
Larger airways become more compressible due to reduction of smooth muscle tone

18. Respiratory complications during Anesthesia induction in a patient with mediastinal mass?
With diaphragmatic paralysis there is elimination of normal transpleural pressure gradient which acts to maintain airway patency during inspiration.
loss of tone of the chest muscles lead to loss of structural support to the airway.
LMA insertions and all other modalities practised in standard difficult airway algorithm may be of no value because airway obstruction occurs distally!

19. Respiratory complications during Anesthesia induction in a patient with mediastinal mass?
Prolonged compression of trachea may result in tracheomalacia. which may interfere with weaning from ventilator.

20. Cardiovascular Challenges!
Cardiac compressions may result in rhythm disturbances and syncopal attack.
Diastolic filling may be compromised due to mass effect or pericardial effusion.
Presence of pericardial effusion has been proved to be definitely associated with adverse outcome in postoperative period.
Central venous access may be difficult due to compression of SVC

21. Risk Evaluation: What is the nature of Surgery /Procedure? Biopsy?
Definitive Surgery or Excision?

22. Risk Evaluation: 1.From symptoms and signs A. Asymptomatic
B. Mild: Can lie supine with some cough/pressure sensation
C. Moderate: Can lie supine for short periods but not indefinitely
D. Severe: Cannot tolerate supine position.

23. Imaging studies: Chest X-ray: Postero-anterior and lateral views.
Location of the mass
Dimension of the mass
Tracheobronchial compression.
Nature of the mass (cystic, solid or calcified) to be examined
More Information needed

24. CT scan: To delineate the anatomy The size of tumour
Contour, perimeter of capsule, septum, haemorrhage, necrotic or cystic component, calcification, homogeneity within tumour
Presence of mediastinal lymphadenopathy, pleural effusion and great vessel invasion are assessed.
It also serves to assessment of airway compression by variety of indexes.

25. …CT scan: What Info It Gives
Tracheal diameter: A 35% decrease in the diameter of tracheobronchial lumen is associated with respiratory symptoms
Greater than 50% decrease may be associated with complete airway obstruction during induction or emergence from GA
Tracheal cross section area: age in years / 9, plus 0.35 cm2 for boys and girls up to the age of 14 years[tempe].
cross sectional area ≥50% of predicted then significant respiratory complications even if the patient is asymptomatic

26. CT scan: What Info It Gives
.Mediastinal mass ratio” (MMR) is maximum width of the mediastinal mass relative to the maximum width of the mediastinum, measured by the CT scan.
MMR more than 56% is associated with increased respiratory complications
Mediastinal thoracic ratio (MTR) is calculated by comparing the size of the mediastinal mass with the thoracic diameter. A patient with a MTR of more than 50% has higher risk of perioperative respiratory complications.

28. MRI imaging modality to delineate soft tissue relation of mediastinum.
Chemical-shift MRI has been shown to be useful in distinguishing normal thymus and thymic hyperplasia from thymic neoplasms and lymphoma

29. Transthoracic echocardiography:
Delineates cardiac involvement by the mass
Patients with cardiovascular symptoms, rhythm disturbances, suspected pericardial effusion
Those patients unable to give an adequate history
Information regarding pulmonary and systemic vascular compression.
Neoplastic involvement of heart or pericardium may pose additional threat by precipitating sudden severe hemodynamic catastrophe

30. Flow volume loops:
Midexpiratory plateau when changing from the upright to the supine
Compression to be considered severe if PEFR is less than 50% of the predicted and supine flow volume loop study shows severe expiratory plateau

31. Identification of children at risk
Airway narrowing/displacement on imaging
Anterior location of tumor
Histologic diagnosis of lymphoma
Symptoms/signs of superior vena cava obstruction
Radiologic evidence of vessel compression
Pericardial effusion
Pleural effusion

32. Management algorithm for diagnostic procedure

33. Management protocol for definitive surgery: ….
In preoperative clinic,
Categorization of patients according to symptoms
Identification of patients at risk
Preoperarive chemotherapy and/or radiotherapy for neoplastic masses
Needle aspiration of cystic nonvascular lesions
Determination of patient position in which airway and cardiovascular compression is minimal.

34. Goals of Anaesthetic management:
1.Avoid compressive effects.
2. Flexibility in patient positioning.
3.Supine position is not mandatory
4.Avoidance of preoperative sedatives.
5.Mandatory preoperative establishment of femorofemoral bypass in selective cases.
6.Spontaneous ventilation as far as practicable.
7.Secure airway beyond stenosis when patient is awake, if feasible

35. Goals of Anaesthetic management:
8.Availability of rigid bronchoscope throughout the procedure7.
9.Short acting muscle relaxant after airway is secured and/or femorofemoral bypass is established7.
10.Strict intraoperative and postoperative monitoring and adequate analgesisa.
11.Postoperative mechanical ventilation when indicated.

36. Algorithmic approach for an adult with mediastinal mass

37. Role of cardiopulmonary bypass:
Recent studies have clearly indicated that ‘standby’ cardiopulmonary bypass is not a good option views of Slinger P and Karsli C, “Patients with severe positional symptoms due to airway or cardiovascular compression cannot be safely given induction of general anesthesia, even with maintenance of spontaneous ventilation, unless an alternative technique to maintain oxygenation or circulation (extracorporeal membrane oxygenation or cardiopulmonary bypass) has been established.”

38. Airway emergency: Prevention and treatment.

39. Take Home Message:
1.Use of Empirical chemotherapy in case of Mediastinal masses of neoplastic origin 2.Aspiration if cystic in nature before induction in the preoperative clinic so as to minimize the compressive effect of the mass. 3.Cardiopulmonary bypass should be instituted in an elective manner in selective cases and not as a rescue option 4.Categorization of patients into different risk groups is essential and both the clinical and radiological criteria must be observed to arrive a management approach.

40. References:
Bitter D. Respiratory obstruction associated with induction of general anesthesia in a patient with mediastinal Hodgkin’s disease. Anesth Analg. 1975; 59:399–403
Bechard P, Letourneau L, Lacasse Y, Cote D, Bussieres J. Perioperative cardiorespiratory complications in adults with mediastinal mass: incidence and risk factors. Anesthesiology 2004; 100:826–83.
Johnson D, Shah P. Mediastinum. In: Standring S editor. Gray’s anatomy: Thorax.29th ed: Elsevier Churechill Livingstone;
Shields TW. General Thoracic Surgery: The mediastinum, its compartments and the mediastinal lymph nodes. 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2000.
Daniel P, Raymond T, Daniel M. Mediastinal anatomy and mediastinoscopy. In: Sellke MD, Nido PJD, Swanson SJ. Editor. Sabiston & Spencer Surgery of the chest: Mediastinum. 7th ed. Philadelphia: Elsevier Saunders; 2005.
Neuman GG, Weingarten AE, Abramowitz RM et al. The anaesthetic management of the patient with an anterior mediastinal mass. Anesthesiology. 1984; 60:
Datt V, Tempe DK. Airway management in patients with mediastinal mass. Indian J Anaesth. 2005; 49(4):
Slinger PD, Campos JH. Anesthesia for thoracic surgery. In Miller RD editor. Miller’s anesthesia. 8thed. Philadelphia: Elsevier Saunders;
Gothard JW. Anesthetic considerations for patients with anterior mediastinal masses. Anesthesiol Clin Jun; 26(2): , vi. doi: /j.anclin