Anaesthesia for patients with mediastinal masses
J. Pullerits FRCPC
0
R. Holzman
0
0
Department of Anesthesia, The Children's Hospital and the Department of Anaesthesia, Harvard Medical School
,
Boston, Massachusetts
,
U.S.
A. Anesthesia
,
The Children's Hospital
,
300 Longwood Avenue, Boston, Massachusetts, USA 02115
Anaesthesia for patients with mediastinal masses may be associated with significant respiratory and cardiovascular complications. In this review, we discuss the anatomical and pathological considerations in these adult and paediatric patients and the three types of intra-thoracic compromise that may be found: compression of the tracheobronchial tree, compression of thepulmonary artery and heart and the superior vena caval syndrome. Patient evaluation by symptom history, computerized tomography and flow.volume loops is emphasized. Preoperative thoracic radiation therapy in severely symptomatic patiems is associated with a decrease in postoperative respiratory complications and an improvement in risk. During radiation therapy a small window can be created to spore some tissue for adequate histological diagnosis. Anaesthetic management techniques for these patients are discussed. Life-threatening complications can occur at any point during anaesthesia for patients with mediastinol masses. Anaesthetists should have a high degree of awareness of the underlying anatomy, pathophysiology and anaesthetic alternatives when caring for these patients.
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Patients with mediastinal masses may require anaesthesia
for incisional or excisional biopsy, staging laparotomy
and a variety of additional procedures during their course
of treatment. A large mediastinal tumour, due to its mass
effects, may be associated with dramatic
cardiopulmonary complications including progressive airway
obstruction, loss of lung volume, pulmonary artery or cardiac
compression and superior vena caval obstruction, i Each
of these complications can cause death during anaesthesia
if not expertly handled. Providing safe anaesthesia for
these patients requires an understanding of the anatomy of
the region, the pathophysiology of the lesions and an
appreciation of their compressive effects on vital
intrathoracic structures.
This review discusses the anatomy of the region, the
pathology and the clinical presentations of the mediastinal
lesions themselves. The preoperative evaluation and
preparation of these patients is discussed, stressing the
need for a thorough CT evaluation of the entire thorax. In
the discussion on the anaesthetic management, we have
stressed that even asymptomatic patients with mediastinal
masses have the potential to develop catastrophic airway
obstruction.
Anatomy
The mediastinum is that portion of the thorax lying
between the fight and left pleural sacs. It is bounded
anteriorly by the sternum and by the bodies of the thoracic
vertebrae posteriorly and extends from the thoracic inlet
superiorly to the diaphragm inferiorly. The mediastinum
is divided into superior and inferior regions by a plane
extending from the sternal angle to the lower border of the
fourth thoracic vertebra. The upper region is named the
superior mediastinum and the lower region, the inferior
mediastinum. The inferior mediastinum is, in turn, divided
into the anterior, middle and posterior mediastina by the
pericardium. Anatomical structures of major importance
to the anaesthetist are found at the junction of the superior,
anterior, middle and posterior mediastina. These
structures include the superior vena cava, the tracheal
bifurcation, the main pulmonary artery, the aortic arch and part
of the superior surface of the heart.
FIGURE 1 Turnoutsof the mediastinum.Reproduced,withpermission,fromthe Cibacollectionof medicalillustrationsby FrankG. NetterMD.
Pathology
Although specific tumours have a predilection for
particular regions of the mediastinum, many kinds of
tumours have been reported in the various mediastinal
regions (Figure 1). In adults, thymomas account for a
large proportion of anterior mediastinal tumours, with a
50 per cent malignancy rate and a 50 per cent association
with a myasthenia gravis symptomatology. Thyroid
tumours may extend below the sternum and present as
anterior mediastinal masses, as may teratomas in their
benign as well as malignant forms. Lymphoid tumours
usually occur in the anterior or middle mediastinum.
Ninety per cent of lymph node masses in the middle
mediastinum are malignant as a result of metastatic
spread. Other masses in the middle mediastinum include
those of vascular origin (aneurysms), oesophagus
(achalasia, diverticula) or cysts (bronchogenic, pericardial).
Masses of the posterior mediastinum are usually of
neurogenic origin (neurofibromas, Schwannomas and
benign ganglioneuromas arising from the sympathetic
chain).
In children, tumours of the mediastinum are most often
bronchial cysts, teratomas, or lymphomas. In a series of
188 children, the majority of malignant tumours were
Hodgkin's and non-Hodgkin's lymphomas of the anterior
and midd (...truncated)