(a)Angiography is a frequently used modality in penetrating extrem-
ity trauma and is the study of choice with some injuries that present with
hard signs. However, when there is evidence of limb ischemia, the patient
should undergo exploration and repair immediately. (c)Fasciotomy is the
treatment for compartment syndrome. Although compartment syndrome
can occur with blunt and penetrating extremity trauma, it is more common
in crush injuries or fractures with marked swelling. It may be required, but
should be performed in conjunction with and after the establishment of
arterial blood flow. (d)Local wound exploration is not recommended
because it may disrupt hemostasis and cause a worsening of the hemor-
rhage. (e)CT scanning is not appropriate in the setting of limb ischemia.
160.The answer is b.(Rosen, p 290.)Cerebral herniation occurs when
increased ICP overwhelms the natural compensatory capacities of the cen-
tral nervous system (CNS). Increased ICP may be the result of posttrau-
matic brain swelling, edema formation, traumatic mass lesion expansion,
or any combination of the three. When increasing ICP cannot be con-
trolled, the intracranial contents will shift and herniate through the cranial
foramen. Herniation can occur within minutes or up to days after a trau-
matic brain injury. Once the signs of herniation are present, mortality
approaches 100% without rapid reversal or temporizing measures. Uncal
herniationis the most common clinically significant form of traumatic
herniation and is often associated with traumatic extracranial bleeding. The
classic signs and symptoms are caused by compression of the ipsilateral
uncus of the temporal lobe. This causes compression of cranial nerve III
leading to anisocoria, ptosis, impaired extraocular movements, and a
sluggish pupillary light reflex. As herniation progresses, compression of
the ipsilateral oculomotor nerve eventually causes ipsilateral pupillary dila-
tion and nonreactivity.
(a)An altered level of consciousness is the hallmark of brain insult from
any cause and results from an interruption of the reticular-activating-system
(RAS) or a global event that affects both cortices. (c)Contralateral dilation is
a late manifestation in brain herniation. (d)Progressive hypertension associ-
ated with bradycardia and diminished respiratory effort is described as
Cushing reflex and is a late manifestation of herniation. (e)Contralateral
hemiparesis develops as herniation progresses.
161.The answer is b.(Rosen, pp 391-392.)Ahemothoraxis the accu-
mulation of blood in the pleural space after blunt or penetrating chest
172 Emergency Medicine