Transcript chestpage1.ppt

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CHEST TRAUMA IN CHILDREN:
CURRENT IMAGING GUIDELINES
AND TECHNIQUES
. Trauma to the pediatric chest,
1-isolation
2-polytrauma,
1-minor 2-life-threatenin.
The challengein pediatric trauma imaging is to
implement a problem-oriented approach that
addresses the specific mechanism of injury
and clinical presentation.
diagnostically accurate, •
cost-effective, •
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efficient treatment decisions, •
using the lowest possible radiation dose. •
The currently availableimaging modalities for •
evaluating chest trauma
include chest radiography, ultrasound, and CT •
scan. •
Chest radiography
relatively low radiation-dose study
ultrasound does not use ionizing radiation
but they both have limitations in
the setting of chest trauma in children
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MultidetectorCT (MDCT) scan
enables rapid acquisition of data sets with
accurate anatomic detail,
delivering valuable multiplanar
three-dimensional
information regarding the morphologic features
of chest injuries.
However, such rapid high resolution
imaging comes with the distinct disadvantage
of delivering higher radiation doses
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EPIDEMIOLOGY AND PATHOPHYSIOLOGY
The most common cause of morbidity
andmortality in children aged 1 to 14 years is
trauma
The National Pediatric Trauma Registry
reported
the incidence of major chest injury to be 6%.
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second only to brain injury as a cause of
The presence of serious chest injury in a •
multiregional trauma patient is an indicationof
the overall severity of the child’s injuries,
increasing the mortality 20-fold compared •
with
children without chest trauma •
The demonstration of clinically silent
concomitant chest injury in
patients with known head, cervical spine,
abdominal,
or extremity injury
substantially affects the
prognosis, especially in children
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In patients with chest injury, there is •
multiregional involvement
(ie, polytrauma) in 50% to 81 •
. Mortality with isolated chest injury is 5% •
one additional body part involvement 25% to •
29%
combination of major chest trauma and •
traumatic
brain injury results in a mortality of 40% •
to70%.
In polytrauma, deaths in children with •
chest trauma are due to nonthoracic causes in •
66% to 75% of cases. •
An age-based classification of the causes of
major chest trauma shows that infants and
toddlers (0–4 years) are usually passive victims
of
child abuse and motor vehicle accidents.
Schoolgoingchildren (5–9 years) sustain
injuries as
pedestrians.
Older children (10–17 years) suffer
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Boys tend to participate in riskier activities,
accounting
for a male to female ratio for chest injury
between
2.6 and 3.0
Blunt chest trauma is about six timesas
common as penetrating chest injury
. Penetratin g injury occurs almost exclusively
in teenagers,typically because of stab wounds
or gun
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Of fatalities associated with blunt chest •
injury, only 14% are due to the chest injury; •
whereas the cause of death in patients with •
penetratingchest injury is directly attributable
to this
injury in 97% of cases •
Rib fractures, flail chest, aortic injury, and •
diaphragmaticrupture are more common in
adults,
whereas pulmonary contusion, •
pneumothorax,
and intrathoracic injury without bony injury •
predominate in children •
The differing pattern of injury may be
explained by the anatomic and physiologic
differences between children and adults.
The trachea is relatively narrow, short, and
more readily compressible in children, so that
small
changes in airway caliber from external
compression
or inhaled foreign body may result in
respiratory compromise that is more
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children have higher metabolic rates and •
consume more oxygen per kilogram
bodyweight than adults consume
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This results ina greater vulnerability to •
develop rapid hypoxia in the context of major
chest trauma.
Injuriey from seatbelts, ejection from a car
restraining device, or airbag deployment often
have unique
features that can be explained by poor
adjustment
of these devices to variable pediatric sizes and
proportions.
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In general, the pediatric body more flexible, •
lighter, and proportioned differently than the
mature individual, leading to unique patterns
of injury.
In adults, whose inflexible ribcages
are more likely to fracture
, more energy is absorbed by the chest wall
and there is relative sparing of the underlying
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Pulmonary contusionsand pneumothorax are •
more common in children,
with comparatively fewer rib fractures •
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Therefore,imaging protocols developed for •
adults do
not necessarily apply to children of all age •
groups.
Radiography
Upright frontal and lateral chest
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polytrauma setting, supine radiographs need for
patient immobilization.
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Attention to technical factors such as
proper collimation and adequate exposure factors
to optimally demonstrate skeletal structures, lung
parenchyma, and mediastinal contours (such as
paraspinal lines) is important
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Ultrasound •
Bedside ultrasonography of the lower chest may
be combined with (FAST) examination of the
abdomen.
Once pleural fluid is encountered,
it is important to screen the entire pleural space,not just the lung bases
. Lower frequency (3.5–7MHz) sector transducers can be used for initial
overview through intercostal and subcostal scanning
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whereas higher frequency (10–12.5 MHz)linear transducers provide for
more detail in the near field, before marking for needle placement
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For certain indications, such as the search for an occult pneumothorax or a
hemopericardium,employ an anterior approach.
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CT Scan •
Once the decision to perform a CT scan has been
made, minimize radiation dosewhile obtaining a diagnostic study.
On multidetecto r scanners, the authors use a kV of 80 to120 and
mA adjusted to both patient weight and age.
More recently, we have implemented automatic
longitudinal dose adjustment based on the
measured attenuation on the scanogram and
preset noise levels that are adapted to the
patient’s age, weight, and clinical indication.
Radiation
dose can be further lowered by novel iterative
image reconstruction techniques that reduce
noise
All studies are preferably obtained with
single-phase CT angiography technique, including
(1) the use of a power injector, (2) rapid bolus injection,
(3) scan acquisition initiated 20 seconds after
(4) The shortest available tube-rotation time and the fastest
available table speed.
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Skeletal Injury •
the rib fracture rate is as low as 1% to 2%
However, it rises substantially in the context of
major pediatric chest trauma to 30% to 60%.
Seventy percent of children with two or more rib
fractures had multisystem injuries, compared to
12% of children with a single fractured rib.
The sites of rib fractures in children differ from
those in adults, being more often posterior than
lateral
A flail chest is rare in children, with a rate
approximately1%.
Fractures of the lower three ribs are
associated with hepatic and splenic injuries
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It is rarely the rib fractures, but
predominantly the associated injuries, that
determine the mortality of children with chest
trauma
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Rib fractures in the0 to 3 year old age group are
the result of childabuse in 39% to 80% of cases.
Rib fracturesare found in 5% to 27% of abused
children
the only skeletal manifestation in 29%.
Multiple aligned posterior rib fractures in a child
less than 3 years has a positive predictive value of
95% for child abuse,
which rises to 100% in the absence of a clear
history of major trauma or underlying metabolic
condition predisposing to fractures.
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Acute nondisplaced rib fractures are notoriously
difficult to identify on anteroposterior (AP) chest
radiographs (Fig. 1A)
. With the exception of suspected child abuse, multiple
radiographic projections in the fracture are not
routinely indicated, as accurate identification does not
typically alter management
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A CT scan is capable of more reliably
detectingnondisplaced fractures search of a suspected
isolated rib
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increased sensitivity of a CT scan, only those rib fractures that were seen
on radiography predicted the development of respiratory failure.
In suspected child abuse, acute nondisplaced rib fractures are best
detected with skeletal scintigraphy
However, owing to the delay in clinical
presentation that is typical in child abuse, healing
fractures with callus (see Fig. 1B) are more
prevalent and these are usually well seen on skeletal
surveys, especially when supplemented by oblique
Views
. For these reasons, the skeletal survey
in combination with scintigraphy when indicated
continues to be the standard of care for the evaluation
of suspected child abuse.
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Fig. 1. Rib fractures in child abuse. A 3-monthold infant with Down syndrome and
congenital heart disease, who
presented to the emergency room with mild
congestive heart failure. (A) Left lateral rib
fracture (arrow) was not
initially detected. Upon return 5 weeks later,
multiple healing rib fractures were seen (B),
and the child was
placed into protective custody.
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Fractures of the upper three ribs signify high energy
impact and are often associated with fractures in the
shoulder girdle and vascular injury.
Scapular and clavicular fractures (Fig. 2) and
posterior sternoclavicular dislocations (Fig. 3),
are often seen in high-impact motor vehicle accidents
involving a shoulder seatbelt. They are also associated
with a high incidence of vascular and cardiac injury.
Sternal fractures or segmental dislocations are more
commonly associated with child abuse but may occur
with other forms ofchest trauma
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Fig. 2. Polytrauma. A 16-year-old girl who was involved in a high-speed motorcycle accident. (A)
Chest radiograph
upon admission shows large, left-sided tension pneumothorax and bilateral clavicular fractures
(arrows).
(B) Repeat radiograph after bilateral chest tube insertion demonstrates decompression of left
tension pneumothorax,
but interval development of a moderately sized, right-sided pneumothorax (note deep sulcus sign),
despite presence of a chest tube. Note extensive chest wall emphysema, right greater than left, and
again the
bilateral clavicular fractures (arrows). Corresponding findings on coronal (C) and axial (D–G) CT scan
images.
Additional findings on CT scanning were a liver laceration (arrow in C, black arrow in G), a
nondisplaced, left
posterior rib fracture (arrow in D), extensive pulmonary contusion and several right-sided lung
lacerations
(arrows in E) and a right-sided hemopneumothorax (fluid levels in F [arrow] and G [white arrow]).
The patient
made a rapid and complete recovery without the need for surgery
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