Chapter 4
Principles of Thoracic Surgery
D. Bruce Panasuk
William R. Alex
Richard N. Edie
I General Principles of Thoracic Surgery
A Anatomy of the thoracic cavity
Thechest wall (Fig. 4-1) is formed by the sternum, ribs, vertebral column, intercostal muscles, intercostal vessels (that run on the undersurface of the ribs), and nerves. Its inferior border is the diaphragm. It is lined internally by the parietal pleura.
The mediastinum (Fig. 4-2) is the anatomic region between the pleural cavities for the length of the thorax.
Theanterior compartment extends from the undersurface of the sternum to the pericardium and contains the thymus gland, lymph nodes, ascending and transverse aorta, and great veins.
Thevisceral compartment extends from the pericardium to the anterior longitudinal spinal ligament and and contains the pericardium, heart, trachea, hilar structures of the lung, esophagus, phrenic nerves, and lymph nodes.
Theparavertebral sulci are actually potential spaces that contain the sympathetic chains, intercostal nerves, and descending thoracic aorta.
Lungs and tracheobronchial tree (Fig. 4-3)
Theright lung has three lobes—the upper, middle, and lower—separated by two fissures.
The major (oblique) fissure separates the lower lobe from the upper and middle lobes.
The minor (horizontal) fissure separates the upper lobe from the middle lobe.
Theleft lung has two lobes—the upper and the lower. The lingula is a portion of the upper lobe. The lobes are separated by a single oblique fissure.
Bronchopulmonary segments are intact sections of each lobe that have a separate blood supply, allowing segmental resection. There are ten bronchopulmonary segments on the right and eight bronchopulmonary segments on the left.
Thetracheobronchial tree (see Chapter 5, IX A ) is formed from respiratory epithelium with reinforcing cartilaginous rings; the branching bronchial tubes are progressively smaller, down to a diameter of 1–2 mm.
The blood supply is dual.
Pulmonary artery blood is unoxygenated.
Bronchial artery blood is oxygenated.
Lymphatic vessels are present throughout the parenchyma and toward the hilar areas of the lungs.
Lymphatic flow in the pleural space is from parietal pleura to visceral pleura.
Lymphatic drainage within the mediastinum is cephalad, flowing along the paratracheal areas toward the scalene nodal areas.
Generally, lymphatic drainage affects ipsilateral nodes, but contralateral flow often occurs from the left lower lobe.
B General thoracic procedures
Radiologic diagnostic procedures. The standard procedures consist of the chest radiograph and computed tomography (CT) scan. These studies are very useful in localizing a process anatomically as well as delineating cavitation, calcification, lymphadenopathy, or multiple lesions. Magnetic resonance imaging (MRI) may be used when a vascular lesion is suspected or if vascular involvement is anticipated.
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FIGURE 4-1 Chest wall. (Adapted from
Way L. Thoracic wall, pleura, lung, and mediastinum. In: Way LW, ed. Current Surgical Diagnosis and Treatment. 10th ed. Stamford, CT: Appleton & Lange; 1983:319.
)
FIGURE 4-2 The anatomic compartments of the mediastinum.
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FIGURE 4-3 Lungs and tracheobronchial tree. (Courtesy of Thomas C. King and Craig R. Smith. Columbia Presbyterian Hospital, New York.)
Endoscopy
Laryngoscopy is occasionally an important procedure when carcinoma of the lung is suspected. Tumor involvement of the recurrent laryngeal nerves (signifying inoperability) can be diagnosed via laryngoscopy when suspicion is raised by vocal cord paralysis with resultant hoarseness.
Bronchoscopy is useful in many diseases of the tracheobronchial tree for both diagnostic and therapeutic purposes.
Diagnostic uses
To confirm a lung or tracheobronchial tumor suggested by history, physical examination, or chest radiograph
To identify the source of hemoptysis
To obtain specimens for culture and cytologic examination from an area of persistent pulmonary atelectasis or pneumonitis
To obtain tissue biopsy
Therapeutic uses
To remove a foreign body
To remove retained secretions (e.g., after administration of general anesthesia or from aspiration of gastric contents)
To drain lung infections, such as abscesses
Types
Rigid bronchoscopy allows visualization of the trachea and main bronchi to the individual lobes.
It is excellent for biopsies of endobronchial lesions and for clearing of thick secretions and blood.
The performance of rigid bronchoscopy under local anesthesia requires considerable skill.
Flexible fiberoptic bronchoscopy is used more frequently.
It is particularly helpful for visualizing lobar bronchi and small bronchopulmonary segments and for the biopsy of lesions in that area.
Although not as effective as rigid bronchoscopy, it may also be used for clearing secretions.
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It is especially useful when the patient is intubated, allowing the bronchoscope to be introduced through the endotracheal tube, thus retaining the airway.
Specific advantages
Biopsy for suspicion of endobronchial or parenchymal tumor may be performed transbronchially via the bronchoscope in approximately one third of cases. Pneumothorax is a rare complication that occurs in fewer than 1% of cases.
Parenchymal biopsies are also useful if an infection is suspected. Infections, such as those caused by Pneumocystis carinii , can be diagnosed with fixed tissue specimens and may require biopsy.
Widening of the tracheal carina in patients with lung tumors can be seen on bronchoscopy. It suggests distortion of the tracheal anatomy by subcarinal nodes and is a poor prognostic sign.
Mediastinoscopy is a procedure in which a lighted hollow instrument is inserted behind the sternum at the tracheal notch and directed along the anterior surface of the trachea in the pretracheal space.
Diagnostic uses
Direct biopsy of paratracheal and subcarinal lymph nodes. Positive nodes may either indicate the need for preoperative chemotherapy or unresectability.
It is also useful for diagnosing other pulmonary problems, such as sarcoidosis, lymphoma, and various fungal infections.
Mortality rate is less than 0.1%.
Complications include hemorrhage, pneumothorax, and injury to the recurrent laryngeal nerves, although the incidence is extremely low.
Scalene node biopsy
The scalene node-bearing fat pad is located behind the clavicle in the region of the sternocleidomastoid muscle. This area should be palpated in patients suspected of having lung tumors and should be biopsied if nodes are palpable.
Tumor is found in 85% of patients with palpable nodes but in fewer than 5% of patients with nonpalpable nodes.
The scalene nodes are surrounded by important structures, including the pleura, subclavian vessels, thoracic and other large lymph ducts, and phrenic nerves. The main complications of scalene node biopsy result from injury to these structures (e.g., pneumothorax, hemorrhage, chyle leak, and diaphragmatic paralysis).
Diagnostic pleural procedures
Thoracentesis. Pleural effusions are examined for organisms in suspected infections and are examined cytologically in suspected malignancies. Positive cytologic findings prove a tumor to be
inoperable. Pneumothorax is the main complication of this procedure.
Pleural biopsy. Either percutaneous or open pleural biopsy yields a positive diagnosis in 60%–80% of patients with tuberculosis or cancer when a pleural effusion or pleural -based mass is present. Pneumothorax is the main complication of this procedure.
Lung biopsy
Diagnostic uses. Percutaneous lung biopsy may be used for either a localized peripheral lesion or a diffuse parenchymal process.
Types
CT––directed fine needle aspiration biopsy is an excellent method for obtaining tissue for tumor diagnosis. However, sampling errors do exist, and a biopsy negative for a tumor does not rule out the existence of a tumor. Needle biopsy may also be useful for the diagnosis of infections and inflammatory processes.
Complications of needle biopsy are pneumothorax and hemorrhage.
Open lung biopsy is necessary if needle biopsy fails to diagnose the problem. Open biopsies or resections are ultimately necessary for many lesions of the chest.
Thoracic exposure for various diseases is provided by different thoracic incisions , for example:
Median sternotomy (Fig. 4-4) for exposure of the heart, pericardium, and structures in the anterior mediastinum
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FIGURE 4-4 Median sternotomy. (Adapted from
Kirklin JW, Barratt-Boyes BG. Hypothermia, circulatory arrest, and cardiopulmonary bypass. In: Cardiac Surgery. New York: Wiley; 1986:62.
)
Posterolateral thoracotomy (Fig. 4-5) for exposure of the lung, esophagus, and posterior mediastinum
Axillary thoracotomy (Fig. 4-6) for limited exposure of the upper thorax during procedures such as upper lobe biopsy or sympathectomy
Anterolateral thoracotomy (Fig. 4-7) for rapid exposure in patients with thoracic trauma or in patients with a very unstable cardiovascular status who cannot tolerate a lateral incision. This type of procedure also allows for excellent control of the airway during the incision.
Anterior parasternal mediastinotomy (Chamberlain procedure), a 2–3 cm parasternal incision that allows insertion of a mediastinoscope into the mediastinum or, more commonly, direct visualization and biopsy of mediastinal lymph nodes
Video-assisted thoracic surgery (VATS) has become a frequently performed and well-tolerated procedure for numerous pleural and pulmonary diseases.
Procedure. A lighted rigid scope connected to a video display is passed into the pleural space, providing comprehensive intrathoracic visualization. This technique permits major procedures to be performed through minor incisions, using a combination of conventional and unique instrumentation. However, the greatest advantage of VATS is the avoidance of a rib -spreading thoracotomy.
Applications of VATS include the diagnosis or management of
Idiopathic exudative pleural effusion
Known malignant pleural effusion
Diffuse interstitial lung disease
Recurrent pneumothorax or persistent air leak
Indeterminate peripheral solitary pulmonary nodules
Mediastinal cyst
Anatomic lobectomy (in experienced hands only)
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FIGURE 4-5 Posterolateral thoracotomy. (Adapted from
Bryant LR, Morgan CV Jr. Chest wall, pleura, lung, mediastinum. In: Schwartz SI, Shires GT, Spencer, FC. eds. Principles of Surgery. 5th ed. New York: McGrawHill; 1989:634.
)
FIGURE 4-6 Axillary thoracotomy. (Adapted from
Bryant LR, Morgan CV Jr. Chest wall, pleura, lung, and mediastinum. In: Schwartz SI, Shires GT, Spencer, FC, eds. Principles of Surgery. 5th ed. New York: McGraw-Hill; 1989:637.
)
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FIGURE 4-7 Anterolateral thoracotomy.
II Thoracic Trauma
Most thoracic trauma can be managed nonoperatively, using expeditious control of the airway and thoracostomy tube drainage of the pleural space. Less than 25% of chest injuries require surgical intervention. Thoracic trauma can be divided into immediate life -threatening injuries and potentially life -threatening injuries, according to the designation by the American College of Surgeons Committee on Trauma.
A
Immediate life -threatening injuries are those that can cause death in a matter of minutes and, therefore, must be rapidly identified and treated during the initial evaluation and resuscitation.
Airway obstruction quickly leads to hypoxia, hypercapnia, acidosis, and cardiac arrest. The highest priority is rapid evaluation and securing the upper airway by clearing out secretions, blood, or foreign bodies; endotracheal intubation; or cricothyroidotomy.
Tension pneumothorax implies that the pleural air collection is under positive pressure that is significant enough to cause a marked mediastinal shift away from the affected side.
Causes. Tension pneumothorax is caused by a check -valve mechanism in which air can escape from the lung into the pleural space but cannot be vented. It is a cause of sudden death.
Clinical presentation. The collapsed lung results in chest pain, shortness of breath, and decreased or absent breath sounds on the affected side. Hypotension results from mediastinal shift to the contralateral side, which compresses and distorts the vena cavae and obstructs venous return to the heart.
Treatment. The thorax must be decompressed with a needle, which is replaced by an intercostal tube with underwater seal and suction.
Open pneumothorax describes an injury in which an open wound in the chest wall has exposed the pleural space to the atmosphere.
Clinical presentation. The open wound allows air movement through the defect during spontaneous respiration, causing ineffective alveolar ventilation.
Treatment involves covering the wound and inserting a thoracostomy tube. Later, debridement and closure of the wound may be necessary.
Massive hemothorax occurs with the rapid accumulation of blood in the pleural space, which causes both compromised ventilation as well as hypovolemic shock.
Treatment entails securing intravenous access and beginning volume restoration followed immediately by placement of a thoracostomy tube.
Complications
If the hemothorax is inadequately drained, the patient may develop an empyema or fibrothorax, both of which would require subsequent thoracotomy and decortication.
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Initial drainage of at least 1000 mL or continued hemorrhage at the rate of 200 mL/hour for 4 hours is an indication for prompt surgical exploration.
Cardiac tamponade occurs with the rapid accumulation of blood in the pericardial sac, which causes compression of the cardiac chambers, decreased diastolic filling, and thus, decreased cardiac output.
Clinical presentation includes hypotension with neck vein distention.
Treatment is prompt pericardial decompression either by pericardiocentesis (if in extremis) or via median sternotomy or left anterior thoracotomy (if more stable).
Flail chest. Blunt chest trauma, causing extensive anterior and posterior rib fractures or sternocostal disconnection, results in paradoxical chest wall movement.
Clinical presentation. Paradoxical chest wall movement interferes with the mechanics of respiration and, if severe, causes acute alveolar hypoventilation. Morbidity is also related to underlying lung injury.
Treatment includes adequate pain control (intercostal blocks or epidural narcotics) and aggressive pulmonary toilet. Mechanical ventilation may be required in severe cases.
B Potentially life-threatening injuries
Potentially life -threatening injuries are those that, left untreated, would likely result in death, but that usually allow several hours to establish a definitive diagnosis and institute appropriate treatment.
Tracheobronchial disruption usually occurs within 2 cm of the carina.
Diagnosis is made by bronchoscopy and is suspected when a
Collapsed lung fails to expand, following placement of a thoracostomy tube
Massive air leak persists
Massive progressive subcutaneous emphysema is present
Treatment is by primary repair.
Aortic disruption is the result of a deceleration injury in which the mobile ascending aorta and arch move
forward while the descending thoracic aorta remains fixed in position by the mediastinal pleura and intercostal vessels. This movement causes a tear at the aortic isthmus, just distal to the takeoff of the left subclavian artery.
Clinical presentation. The aortic injury usually results in fracture of the intima and media with the adventitia remaining mainly intact. However, complete disruption of all layers can occur with the hematoma contained only by the intact mediastinal pleura.
Chest radiograph findings include:
Widened mediastinum
Indistinct aortic knob
Depressed left main stem bronchus
Apical cap
Deviation of trachea to the right
Left pleural effusion
Diagnosis is confirmed by an aortogram.
Treatment involves repair by interposition graft with or without some method of distal perfusion.
Diaphragmatic disruption results from blunt trauma to the chest and abdomen, producing a radial tear in the diaphragm, beginning at the esophageal hiatus.
Diagnosis is by chest radiograph, which shows evidence of the stomach or colon in the chest.
Treatment
The immediate placement of a nasogastric tube (if not already in place) will prevent acute gastric dilatation, which can produce severe, life -threatening respiratory distress. This is followed by urgent transabdominal repair with simultaneous treatment of any associated intra - abdominal injuries.
If rupture is not diagnosed until 7–10 days later, transthoracic repair is recommended to free any adhesions to the lung that might exist.
Esophageal disruption usually results from penetrating trauma rather than blunt trauma.
Clinical presentation. It causes rapidly progressive mediastinitis.
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Treatment is wide mediastinal drainage and primary closure with tissue reinforcement (pleura, intercostal muscle, or stomach).
Cardiac contusion results from direct sternal impact. It ranges in severity from subendocardial or subepicardial petechiae to full -thickness injury.
Functional complications
Arrhythmias (i.e., premature ventricular contractions, supraventricular tachycardia, and atrial fibrillation)
Myocardial rupture
Ventricular septal rupture
Left ventricular failure
Diagnosis is made by an electrocardiogram, isoenzymes, and two-dimensional (2D) echocardiogram.
Treatment includes cardiac and hemodynamic monitoring, appropriate pharmacologic control of arrhythmias, and inotropic support if cardiogenic shock develops.
Pulmonary contusion is the most common injury seen in association with thoracic trauma (30%–75% of all patients have a major chest injury).
Causes. It is caused by blunt trauma, which produces capillary disruption with subsequent intra - alveolar hemorrhage, edema, and small airway obstruction.
Diagnosis is made by chest radiograph, arterial blood gas, and clinical symptoms of respiratory distress.
Treatment includes fluid restriction, supplemental oxygen, vigorous chest physiotherapy, adequate analgesia (epidural narcotics), and prompt chest tube drainage of any associated pleural space complication.