Abstract
- The trachea divides into the right and left main bronchi at the level of the sternal angle (T4 level). The right bronchus is wider, shorter, and more vertical compared to the left. The right bronchus divides into three lobar bronchi, supplying the right upper, middle, and lower lung lobes respectively. The left bronchus divides into two lobar bronchi, supplying the left upper and lower lobes.
- The lung has a unique dual blood supply. The pulmonary artery trunk originates from the right ventricle and gives the right and left pulmonary arteries. The right pulmonary artery passes posterior to the aorta and superior vena cava. The left pulmonary artery courses anterior to the left mainstem bronchus. The pulmonary arteries supply deoxygenated blood from the systemic circulation directly to alveoli where gas exchange occurs. These vessels are large in diameter, but supply blood in a low pressure system.
- The bronchial arteries arise directly from the thoracic aorta. These vessels are smaller in diameter, and supply the trachea, bronchial tree, and visceral pleura.
- The venous drainage of the lungs occurs from the pulmonary veins. They originate at the level of the alveoli. There are two pulmonary veins on the right and two on the left. These four veins join at or near their junction with the left atrium usually within the pericardium. These veins carry oxygenated blood back to the heart for distribution to the systemic circulation.
- The lung is covered superiorly, anteriorly, and posteriorly by pleura. At its inferior border the investing layers come into contact forming the inferior pulmonary ligament that connects the lower lobe of the lung, from the inferior pulmonary vein to the mediastinum and the medial part of the diaphragm. It serves to retain the lower lung lobe in position.
Surgical Anatomy
The trachea divides into the right and left main bronchi at the level of the sternal angle (T4 level). The right bronchus is wider, shorter, and more vertical compared to the left. The right bronchus divides into three lobar bronchi, supplying the right upper, middle, and lower lung lobes respectively. The left bronchus divides into two lobar bronchi, supplying the left upper and lower lobes.
The lung has a unique dual blood supply. The pulmonary artery trunk originates from the right ventricle and gives the right and left pulmonary arteries. The right pulmonary artery passes posterior to the aorta and superior vena cava. The left pulmonary artery courses anterior to the left mainstem bronchus. The pulmonary arteries supply deoxygenated blood from the systemic circulation directly to alveoli where gas exchange occurs. These vessels are large in diameter, but supply blood in a low pressure system.
The bronchial arteries arise directly from the thoracic aorta. These vessels are smaller in diameter, and supply the trachea, bronchial tree, and visceral pleura.
The venous drainage of the lungs occurs from the pulmonary veins. They originate at the level of the alveoli. There are two pulmonary veins on the right and two on the left. These four veins join at or near their junction with the left atrium usually within the pericardium. These veins carry oxygenated blood back to the heart for distribution to the systemic circulation.
Figure 17.2 (a, b) Anatomy of the left hilum. The pulmonary artery is the superior-most structure within the pulmonary hilum. Note the close relationship between the inferior pulmonary vein and inferior pulmonary ligament. Caution should be taken to avoid injury to the vein during division of the ligament. (c, d) Anatomy of the left hilum. The pulmonary artery is the superior-most structure within the pulmonary hilum. Note the close relationship between the inferior pulmonary vein and inferior pulmonary ligament. Caution should be taken to avoid injury to the vein during division of the ligament. PV, pulmonary vein.
Figure 17.3 (a, b) Anatomy of the right hilum. There are two structures located anteriorly; the pulmonary artery superiorly, and the superior pulmonary vein inferiorly. The posterior-most structure is the right mainstem bronchus. The inferior-most structure is the inferior pulmonary vein.
The lung is covered superiorly, anteriorly, and posteriorly by pleura. At its inferior border the investing layers come into contact forming the inferior pulmonary ligament that connects the lower lobe of the lung, from the inferior pulmonary vein to the mediastinum and the medial part of the diaphragm. It serves to retain the lower lung lobe in position.
General Principles
Lungs have high blood flow, but are part of a low-pressure system. In addition, the lung tissue is rich in tissue thromboplastin. This combination results in spontaneous hemostasis from the lung parenchyma in the majority of cases. Hilar or central lung injuries are the most common cause of massive lung hemorrhage, requiring operative management.
About 80% to 85% of penetrating and more than 90% of blunt trauma to the lungs can safely be managed with thoracostomy tube drainage and supportive measures alone.
Lung-sparing nonanatomical lung resections are preferable to more extensive anatomical resections.
Pneumonectomy after trauma is associated with very high mortality.
Special Surgical Instruments
The surgeon should have readily available a standard vascular tray, Finochietto retractor, Duval clamps, Allison lung retractor, and a sternal saw or Lebsche knife.
Anesthesia Considerations
If the hemodynamic condition of the patient allows, insert a double-lumen tube.
Maintain low tidal volumes to reduce the risk of air embolism.
Positioning
The patient is placed supine on the operating room table with both arms abducted to 90°. Skin preparation should include the neck, anterior, and bilateral lateral chest walls and the abdomen down to the groins.
Incisions
Median Sternotomy
It is the incision of choice in penetrating injuries to the anterior chest, with suspected cardiac or anterior mediastinal vascular injuries. It provides good exposure of the heart, the anterior mediastinal vessels, both of the lungs, the middle and distal trachea, and left mainstem bronchus. It is quick to perform, relatively bloodless, and causes less postoperative pain and fewer respiratory complications than a thoracotomy. However, it does not allow for good exposure of the posterior mediastinal structures and does not provide adequate access for cross-clamping of the thoracic aorta for resuscitation purposes. The technique is described in Chapter 14, General Principles of Chest Trauma Operations.
Anterolateral Thoracotomy
It is the preferred incision in cases with lung injuries. The technique is described in Chapter 14.
Clamshell Thoracotomy
It is usually performed as an extension of a standard anterolateral thoracotomy to the opposite side, for suspected bilateral lung injuries, superior mediastinal vascular injuries, or cardiac resuscitation and aortic cross-clamping purposes. The technique is described in Chapter 14.
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