saturation, and increasing A-a gradient. Hemoptysis may be present in up
to 50% of cases. Typical radiographic findings begin to appear within min-
utes of injury and range from patchy, irregular, alveolar infiltrate to frank
consolidation.
(a)Diaphragmatic injuries are relatively rare and result from either
blunt trauma or penetrating trauma. Almost 90% occur on the left side since
the liver protects and prevents herniation of abdominal organs through
right-sided defects. (b)Hemothorax usually occurs secondary to penetration
of pulmonary parenchyma or injury to intercostal or internal mammary ves-
sels that leads to intrathoracic bleeding. Patients may be dyspneic and have
pleuritic, chest, shoulder, or back pain. Typically, patients are tachypneic
and have absent breath sounds and dullness to percussion of the chest sec-
ondary to the accumulation of blood. (c)A tension PTX is a clinical diagnosis
in which air can enter the pleural cavity but cannot escape leading to a shift
in the mediastinum, which results in impeding venous blood return to the
heart. Lung examination generally reveals absent breath sounds on the side
of injury. (e)Pulmonary contusion should be differentiated from ARDS with
which it is often confused. The contusion usually manifests itself within min-
utes of the initial injury, is usually localized to a segment or a lobe, is usually
apparent on the initial chest radiograph, and tends to last 48 to 72 hours.
ARDS is diffuse, and its development is usually delayed, with onset typically
between 24 and 72 hours after injury.
159.The answer is b.(Scaletta and Schaider, pp 243-244.)Clinical mani-
festations ofpenetrating arterial injury of the extremityare generally
divided into “hard signs” and “soft signs.” Hard signs include pulsatile bleed-
ing, expanding hematoma, palpable thrill or audible bruit, and evidence of
distal ischemia (eg, pain, pallor, pulselessness, paralysis, paresthesia, poikilo-
thermia). Soft signs include diminished ankle-brachial indices, asymmetri-
cally absent or weak distal pulse, history of moderate hemorrhage or wound
close to a major artery, and a peripheral nerve deficit. Emergent surgery is
generally necessary when there are hard signsof vascular injury. Although
the management of penetrating extremity injury is evolving, whenever there
isevidence of distal ischemia, the patient should be taken to the OR for
exploration and repair.When severe ischemia is present, the repair must be
completed within 6 to 8 hours to prevent irreversible muscle ischemia and
loss of limb function. In the presence of hard signs without evidence of
ischemia, some surgeons may prefer to first perform angiography to better
define the injury.
Trauma Answers 171