Airway Management and Problems with Lung Isolation in Thoracic

Airway Management and Lung Isolation in Patients with Thoracic Aortic
Aneurysms
Javier H. Campos, M.D.
Professor of Anesthesia
Executive Medical Director of Operating Rooms
Vice Chair for Clinical Affairs
Director of Cardiothoracic Anesthesia
Department of Anesthesia
University of Iowa Health Care
Iowa City, IA 52241
email: [email protected]
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Introduction
Thoracic aortic aneurysm is usually a potentially life-threatening medical condition that causes short-long
term mortality due to rupture and dissection. Airway compression due to thoracic aortic aneurysm
represents a challenge particularly in the case requiring lung separation to achieve one-lung ventilation
(OLV). The purpose of this workshop will be focused on:
1.
2.
3.
4.
5.
Anatomic presentation of thoracic aortic aneurysm
Clinical presentation of tracheobronchial compression caused by the aneurysm
Evaluation of radiological images to recognize airway compression
Lung separation techniques in patients with thoracic aneurysm and normal airway
Options with lung isolation and difficult airway
Anatomic Presentation of Thoracic Aortic Aneurysm
The thoracic aorta can be divided into three major parts: the ascending aorta, aortic arch and descending
aorta. The aortic arch begins at the level of the upper border of the second sternocostal articulation of the
right side, and run at the first upward, backward and to the left in front of the trachea; it is then directed
backward in the left side of the trachea and finally passes downward in the left side of the body of the
fourth thoracic vertebrae, at the lower border of which it becomes continuous with the descending aorta.
The descending thoracic aorta extends from the ligamentum arteriosum to the aortic hiatus at the level of
the diaphragm.
The trachea is located in the midline position, but often can be deviated to the right at the level of the
aortic arch, with a greater degree of displacement in the setting of an atherosclerotic aorta, dilated aorta,
advanced age or in the presence of severe chronic obstructive pulmonary disease (COPD). With COPD
or aging, the lateral diameter of the trachea may decrease with an increase in the anteroposterior diameter.
Conversely, COPD may also lead to softening of the tracheal rings with a decrease in the anteroposterior
diameter of the trachea.[1-2] Any abnormal enlargement of the aorta can potentially compromise the
airway at the level of the trachea, left main stem bronchus or pulmonary vessels.
Thoracic aortic aneurysms are described according to their location, size and shape. The Stanford
classification describes the aortic dissections as follow: type A: involves ascending aorta or aortic
arch~(60%); and type B involves the descending aorta only ~(40%). This dissection commences distal to
the left subclavian artery. Figure 1 shows (a) A multidetector computed tomography scan of the chest.
(b) A three-dimensional tracheal reconstruction of a 60-year-old male smoker with COPD. The trachea is
displaced to the right side, and there is a narrowing on the bronchial bifurcation. These changes reflect the
smoking history, atherosclerosis and age. AA = Ascending aorta, DTA = descending thoracic aorta
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Figure 1:
A
B
AA
DT
A
The aortic arch extends from the origin of the innominate artery to the insertion of the ligamentum
arteriosum. Tracheobronchial compression is a well-known complication of aneurysms of the ascending
aorta and or the aortic arch.[3-4] In general, compression occurs because the close anatomic relationship
of the aortic arch to the trachea and left mainstem bronchus. In addition obstruction of the distal part of
the trachea or left main-stem bronchi by a descending thoracic aortic aneurysm has been reported.[5-6]
Figure 2 A) displays the ascending, aortic arch and descending thoracic aorta and the relationship with
tracheal carina and left main-stem bronchus. B) displays the lateral view of the ascending, aortic arch and
the descending aorta
Figure 2:
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Clinical Presentation of an Airway Compression by Thoracic Aortic Aneurysm
An ongoing enlargement of a thoracic aortic aneurysm can lead to significant compression of adjacent
structures. Esophageal obstruction from aortic expansion can result in dysphagia. Upper airway
compression due to the thoracic aortic aneurysm usually presents with wheezing, coughing, hemoptysis,
dyspnea, stridor or pneumonitis. An ascending or an aortic arch aneurysm may cause superior vena cava
syndrome as a result of compression of the superior vena cava or innominate vein also a compression of
the left main bronchus and left pulmonary artery has been reported. [7]. In contrast, compression of the
trachea or mainstem bronchus may be a mass effect of aneurysm of the arch or descending aorta and may
result in tracheal deviation.[8] Patients who present with dyspnea sometimes the symptoms may be
positional. Other symptoms include hoarseness from recurrent laryngeal nerve involvement or atelectasis
due to a compression of the lung by the aneurysm.
Evaluation of Radiological Studies to Recognize Airway Compression
In general, all patients with thoracic aortic aneurysm have a chest x-ray which, depending upon the size of
the aneurysm, reveal a massive thoracic aneurysm with widening of the upper mediastinum. On occasion,
if the patient presents with a descending thoracic aortic aneurysm, examination of the chest x-ray might
show tracheal deviation of the right or compression of the left mainstem bronchus due to an aneurysm. If
a nasogastric tube is present, a deviation to the right of the esophagus can be produced by the large
aneurysm.
The examination of the computed tomography scan (CT) of the chest will demonstrate the relationship of
the thoracic aortic aneurysm to adjacent structures. Compression of the tracheobronchial tree specifically
near to the tracheal carina, the pulmonary arteries and veins, as well as superior vena cava can be
identified.[5] Figure 3 displays a computed tomography scan of the chest (CT Scan), a large thoracic
aortic aneurysm with a patent right mainstem bronchus and a severe compression of the left mainstem
bronchus.
Figure 3:
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Compressed left
mainstem bronchus
Patent right main
stem bronchus
Aortic Aneurysm
R
L
Lung Separation Techniques in Patients with Thoracic Aortic Aneurysm with Normal and
Abnormal Airways
Patients who present with a descending thoracic aortic aneurysm and require lung isolation can be
managed with either a left-sided double-lumen endotracheal tube (DLT) (vast majority of these cases with
normal upper or lower airway), or a right-sided DLT if there is a compression of the entrance of the left
mainstem bronchus.[9] The advantage of using a DLT in a descending thoracic aortic aneurysm repair
include: 1) improved surgical conditions (better exposure); 2) less damage to the left lung if heparin is
used; 3) avoidance of contamination with blood into the right lung if the aneurysm ruptures into the left
mainstem bronchus; and 4) easy to suction blood and secretions independently while ventilating the
opposite and dependent lung.
With a large aneurysm of the descending thoracic aorta, the anatomy can be distorted if the aneurysm
compresses the trachea or the entrance of the left mainstem bronchus [6 and10]. This may make the
placement of a left-sided DLT difficult. In a case by Cohen, et al [11], dangerous placement of a leftsided DLT was described in a patient with a descending thoracic aortic aneurysm. The authors reported
the use of moderate inward pressure in the endobronchial lumen for isolation of the left lung. This
maneuver can be dangerous in patients in whom the aneurysm involves the left mainstem bronchus,
because the potential exists for rupture of the aneurysm.
In some cases diagnostic fiberoptic bronchoscopic evaluation will be necessary to evaluate the potential
area of compression prior to the placement of lung isolation devices. Patients with a descending thoracic
aortic aneurysm that compresses 2/3 of the lumen of the entrance of the left main-stem bronchus should
receive a right-sided DLT to avoid a potential complication (rupture) if a forced left-sided DLT is
attempted. For all lung isolation devices used during thoracic aortic aneurysm repair, a complete
fiberoptic bronchoscopy exam must be completed in supine and then in a lateral decubitus position or
whenever a malposition or massive bleeding from one of the lumen occurs.
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A different alternative to facilitate lung isolation in a patient with a descending thoracic aortic aneurysm
is with the use of bronchial blockers. (Univent [mostly used in Japan these days], Arndt®, Cohen® or the
Fuji blocker) [12-13]. The advantage of the bronchial blocker is that it can be used in patients with a
difficult airway or patients that requires an awake intubation (trauma patients with cervical collar and
unclear cervical spine). Because the bronchial blocker relies on the use of a single-lumen endotracheal
tube, one of the advantage of the use of the bronchial blocker is that if the patient requires mechanical
ventilation in the postoperative period (most aneurysms do) withdrawal of the bronchial blocker at the
completion of surgery and keeping the single-lumen endotracheal tube avoids compromising the airway
because there is no need to replace the single lumen endotracheal tube.
Metallic stents have been used for rescuing the upper airway compression due to an aortic aneurysm [8],
bronchoscopy is used to diagnose airway compression and also is being used to deploy expandable
metallic airway stents.[14-15] It is important during the airway management of aortic aneurysm to
recognize if the patient already has a metallic stent in place, in these cases the use of a single-lumen
endotracheal tube plus the use of a bronchial blocker is preferable rather than a DLT if lung isolation is
needed.
Summary
Patients with a large thoracic aortic aneurysm may develop an airway compression. During the
preoperative evaluation review of the posterior-anterior chest x-ray it is important to determine if the
trachea or the left mainstem bronchus has any compression due to a large aneurysm. Also, review of the
chest CT scan will determine the precise location of the compression. Patients with a descending thoracic
aortic aneurysm and no compression of the airway, lung isolation can be managed with a left-sided DLT
or a bronchial blocker. If an occlusion of the left mainstem bronchus is present a right-sided DLT can be
used. For trauma patients with a cervical collar in place or the already intubated patient that requires lung
isolation, these cases can be managed with a bronchial blocker though an existing single-lumen
endotracheal tube. Patients with a metallic stent in place to rescue the airway, fiberoptic bronchoscopy
exam is required prior to advancing of any device to ensure that the stent is not dislodged. Fiberoptic
bronchoscopy is the best method to diagnose an airway compression and confirm optimal position of a
DLT or a bronchial blocker in patients with a descending thoracic aortic aneurysm.
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References:
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Surgery, 2011 pp 227-246. Ed Slinger P. Springer Publisher.
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right subclavian artery aneurysm. Tokai J Exp Clin Med 2002;27:21-26.
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Anesthesia for Thoracic Surgery, 2011 pp 247-258. Ed Slinger P. Springer Publisher
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thoracic aortic aneurysm. Ann Thorac Surg 2012;94:273-274
15. Gelsomino S, Romagnol; S, Dragotto A, et al: Multistep endobronchial endovascular approach in
recurrent acute respiratory failure caused by thoracic aneurysm. J Thorac Cardiovasc Surg 2005; 129:
1436-1438
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