anatomy sections Flashcards
Why do penetrating injuries (stab wounds, gunshot wounds) below the
level of the nipple line require exploratory abdominal surgery?
As can best be seen from the anterior dissection approach, the
diaphragms rise within the bony thorax up to the level of the fourth
intercostal space. Therefore, a knife or bullet that traverses the bony
thorax could enter the abdomen in addition to entering the chest.
Lung cancer, which has spread outside of the pulmonary parenchyma, is
considered surgically incurable. What clinical neurological findings
might suggest that a tumor located in the hilum of the lung is surgically
incurable?
a. Hemidiaphragm elevation due to invasion of the phrenic nerve.
b. Hoarseness due to invasion of the recurrent laryngeal nerve.
c. Delayed gastric emptying due to invasion of the vagus (rare).
d. Horner’s syndrome (ptosis, meiosis, anhydrosis, and
enophthalmos) due to invasion of the sympathetic chain.
What are the two most common chambers of the heart injured in the
setting of anterior stab wounds?
The right ventricle is the most common chamber injured followed by
the right atrium.
A penetrating chest wound results in subcutaneous emphysema (air in
the soft tissues) of the neck. Which intrathoracic organ was injured?
The trachea or the esophagus
What might be the result of increased pressure due to air
(pneumothorax) or blood (hemothorax) in either of the chest spaces?
How might you treat this problem emergently?
Pneumothorax or hemothorax may lead to a shift of the mediastinal
structures from their midline position. This leads to kinking of the
SVC and IVC, which diminishes venous return to the heart and,
therefore, by Starling’s law drops cardiac output. Severe mediastinal
shift can lead to a marked drop in blood pressure and frank shock.
This extreme situation is referred to as either tension pneumothorax
or tension hemothorax. The treatment of either problem is to
emergently place a drainage tube into the pleural space to evacuate air
and/or blood and therefore allow mediastinal structures to regain their
normal position
In placing a subclavian central venous line pulsatile red blood is
obtained. What has happened? Which other structures can be injured
during this procedure?
The central venous line was inadvertently put into the subclavian
artery in this scenario. Other structures that can theoretically be
injured during a subclavian line placement include the sympathetic
chain, thoracic duct, phrenic nerve, and apex of the lung. Perforations
of the lung leading to pneumothorax are by far the most common
complication of central line placement.
In trauma there are only two venous structures in the body that cannot be
clamped or acutely ligated. Which structures are these? Why can
patients tolerate slow occlusion of these venous structures by tumors?
The two venous structures that cannot be ligated are the superior vena
cava and the supra-hepatic inferior vena cava. Slow occlusion of these
vessels by tumor allows for sufficient collateralization by the azygous
and hemi-azygous systems, via upper extremity collaterals
What structures might not be well seen via transesophageal
echocardiography?
Transesophageal echocardiography has an excellent view of all the
valvular structures and cardiac chambers. It also images the
ascending and descending thoracic aorta beautifully. However, the
transverse arch of the aorta is often poorly seen on transesophageal
echo and there can be difficulties seeing the branch pulmonary
arteries and pulmonary veins
When dissecting the superior vena cava free for cannulation, what
structures does one need to be careful to avoid?
The phrenic nerve, the right pulmonary artery, the SA node, and the
right superior pulmonary vein.
What structures might a tracheal tumor erode into and what life
threatening complications might this result in?
Tumors of the trachea can erode into the esophagus leading to a
tracheo-esophageal fistula or into the aorta leading to an aortotracheal
fistula.
Why is it difficult to achieve complete cardiopulmonary bypass
(complete diversion of blood flow through the heart and lungs) from an
incision in the left chest?
From the left chest position it is impossible to access the right atrium
and, therefore, the only option for total cardiopulmonary bypass is
cannulation of the main pulmonary artery.
What neurological signs might be observed in a patient with a
descending thoracic aortic aneurysm?
The same neurological signs that can be seen in a hilar lung tumor:
Horner’s Syndrome, diaphragmatic dysfunction paralysis, hoarseness,
or delayed gastric emptying. These neurologic syndromes are distinctly
uncommon in association with aortic aneurysm.
What structure could be damaged during ligation of a patent ductus
arteriosus?
The most common structure damaged is the recurrent laryngeal nerve.
It is also possible to injure both the phrenic nerve and the thoracic
duct during this procedure
What incisional approach would you use to perform an operation on the
intrathoracic esophagus? Intra-abdominal esophagus? Cervical
esophagus?
The intrathoracic esophagus is best approached through a right
thoracotomy. The intra-abdominal esophagus can be approached via
laparotomy, left thoracotomy, or a combined thoraco-laparotomy. The
cervical esophagus is best approached through a neck incision.
A patient develops a large pleural effusion after an esophagectomy,
which is milky in appearance. What is the cause?
The patient has sustained an injury to the thoracic duct resulting in a
chylothorax. The treatment is reoperation with ligation of the main
branch of the thoracic duct at the esophageal hiatus
