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290 oracic ultrasound
Major and widespread contusions may look like ARDS, the only difference in the early stage
is their location, related to the traumatic event. However, later stages can enhance a mixture
of mechanical traumatic injury and ARDS, as it may follow the blunt event. is subtle
evolution, in our view, highlights the utility of ultrasound in the monitoring of the patient
with trauma.
Chest CT can diagnose many traumatic parenchymal injuries from the initial stage of care.
Many of these injuries are minor and, if not associated with pulmonary lacerations or hematomas, they usually resolve within 3-4 days, causing minimal ventilatory impairment. More
severe lung trauma, with parenchymal injury or hematoma, has a longer lasting radiographic
expression (7-20 days), and a greater pathophysiological potential. In general, the clinical
worsening of a patient with chest trauma has its highest expression around 72 hours85. It is
also known that the volume of pulmonary contusion, relative to the total lung volume, can
predict ARDS and the need for ventilatory support with intubation86. A contusion volume
greater than 20% was associated with a trend toward ARDS in 82% of cases, while a smaller
volume involved a risk of ARDS of 22%87. A contusion greater than 28% of lung volumes
made intubation mandatory in all cases, while patients with a volume of injured parenchyma
less than 18% did not require intubation88.
In our experience, some applications of ultrasound in chest trauma victims are clear. For
example, its role for the assessment of pneumo- and hemothorax is commonly accepted. e
usefulness of thoracic sonography in lung contusion has not yet been defined in the literature.
However, some considerations deserve attention.
An interstitial syndrome expressed as white lung or compact B Lines, in a trauma patient, is
a strong predictor of parenchymal damage in the range of preconsolidating densities. In our
opinion, observation over time can predict the anatomical evolution of this finding. If it is just
an expression of hypoventilation, the improvement after analgesic and respiratory therapy is
rapid. In this case it is defined as a “ghost” contusion, because there is a rapid clearance after
measures aimed at improving ventilation.
A real mild contusion, expressed as interstitial syndrome, usually lasts a few days and can be
conveniently followed in its benign evolution. Persistence or local worsening of the contusion, even if minor, with consolidation,
means progressive loss of air or a local
inflammatory or septic evolution. A bilateral and multifocal bilateral diffusion
RUPTURE OF
THE PARENCHYMA
(with spared areas) of the interstitial and
alveolar syndrome may indicate a trend
toward ARDS.
e most serious contusions produce
images that, as already mentioned, do
not differ much from those of pneumonia and ARDS.
Lung laceration produces a gap in the
tissue, that can be filled with blood and
generate solid images of various shape
and echogenicity, but generally with a
hypoechoic component (hematoma)89
(Fig. 33).
Figure 33 – Rupture of the lung parenchyma with
discontinuity of the pleural line.
oracic trauma 291
A coexistent pneumothorax often masks a contusion, but the contusion is enhanced by a
concomitant pleural effusion. is emphasizes the need to scan the pleural plane after drainage
of a PNX. With this shrewdness, the re-expansion of the lung will be evaluated and acoustic
alterations of the pleural plane can be assessed.
e evidence of interstitial syndrome and coexisting (or temporally subsequent) consolidating lung lesions in the context of a trauma are findings strongly suggestive of traumatic lung
injury. is ultrasound picture may indicate a selective use of CT, a suitable accommodation
for the patient (ICU or ward) or an adequate therapeutic choice (restriction of fluid infusions
or a particular ventilation therapy).
e substantial problem of ultrasound examination is not the ability to detect lung lesions, but
the need to perform scans on all lung surfaces, and this may be difficult, given the conditions
of the injured patient. In addition, lung lesions can be masked by subcutaneous emphysema
or pneumothorax, while the consolidations by the coexisting interstitial syndrome.
Nevertheless, also restricted scans at the level of outbreaks of rib fracture or flail chest may
provide useful data for the management of the patient.
Figure 34 summarizes the role of ultrasonography in the patient with chest trauma.
Trauma ABC
(ATLS)
EFAST
Subcutaneous
emphysema?
CT Drainage
Figure 34 – Role of ultrasonography in the patient with chest trauma.
PNX Hemothorax?
Compression?
Re-expansion?
Contusion?
Focal hypoventilation
Volume?
Therapy
Transient
Signs of contusion?
Progressive
Bilateral
Infection,
atelectasis
ALI/
ARDS
292 oracic ultrasound
➣ Bone traumas
If the total reflection of the ultrasound beam by an acoustically impermeable plane prevents
the vision of the deeper levels, it creates a reflection line that accurately delineates the bone
surface and also allows to detect fractures90.
ese observations are useful when the subcutaneous sternal plane is interrupted and/or deleveled, or when the ribs are similarly interrupted in their continuity. Sometimes a hematoma
appears as a hypoechoic collection contiguous to the broken bone.
A survey of the sternum is quick and easy91 (Fig. 35) (Clip 6). However, physiological interruptions between manubrium, ensiform apophysis and body of the sternum must not be
interpreted as fracture. e role of ultrasound in these cases is the confirmation of non-diriment
radiographic findings92.
Inspiration Expiration
Figure 35 – Fracture of the sternum. The deleveling of the fracture plane of the sternal body is evident
with the respiratory movements.
Clip 6 – Sternal fracture. Movements consensual to respiration are observed.
Rib fractures have an incidence of 7-40% in thoracic trauma. ey are very frequent injuries93,
but the use of ultrasound for their definition is questionable, as their study is quite long and
complicated (Figs. 36-37) (Clip 7).
It is shown that for sternal and rib fractures, ultrasound examination has a higher diagnostic
accuracy compared to radiology. We believe that these lesions are important because they
correlate with amount of mechanical energy that is transmitted on the pulmonary and cardiomediastinal structures, predicting the possibility of internal damages.
A significant proportion of lung contusions lies behind outbreaks of rib fracture, and morbidity, mortality and complications are positively correlated with the number of fractured
ribs, especially in elders94. Some interest arises when identifying a fracture may direct an
echo-guided regional anesthesia with analgesic purposes. A rib block can be achieved using a
long-lasting anesthetic (bipuvicaina 0.25%) that is injected in aliquots of 2-3 ml at the level
of the lower margin of the ribs damaged, a few centimeters behind the fracture.
is technique is effective but penalized by the need to repeat the injections (the maximum duration
is 6-7 hours) and by a significant risk of pneumothorax, if carried out without using ultrasound95.
oracic trauma 293
Some temporary success can also be achieved with echo-guided direct infiltration of the
anesthetic in the fracture outbreaks. On the contrary, the intrapleural instillation of local
anesthetics, which is possible with catheter or a pleural tube, is discussed96.
Fracture
Figure 36 – Rib fracture enhanced by strongly impedant bone surfaces.
Figure 37 – Rib fractures. X-ray (arrows on the left) and ultrasound (right). In ultrasound the cortical
bone is broken at the level of the fracture, with a clear step.
Clip 7 – Rib fracture. Pleural sliding below the ribs.
294 oracic ultrasound
➣ Causes of pulmonary dysfunction in thoracic trauma
Briefly, there are five causes of pulmonary dysfunction after thoracic trauma: pulmonary
contusion, infection, inflammatory lung injury (ALI/ARDS), increased extravascular lung
water and bronchial secretion.
ey act synergistically, resulting in respiratory failure. e exact interpretation and the
coherent therapy of post-traumatic dysfunction depends on a prompt and early diagnosis.
e pulmonary contusion has already been treated. It directly alters the relationships between
ventilation and perfusion through a mixture of collapse of distal airways, alveolar imbibition, interstitial edema and inflammatory/immunological damage to the alveolar-capillary
membrane.
A precise imaging is obtained with CT, but the interstitial and alveolar subpleural components
also have an echographic representation. Treatment is supportive. e ventilatory strategies,
such as PEEP, may benefit from ultrasound and its possibility of evaluating parenchymal
density and recruitment. Uncomplicated contusion findings usually regress in a few days.
In subjects with chest trauma, echographic densities often appear at level of the lung base.
ey appear in ultrasound as white lung, or as poorly ventilated consolidations. Frequently a
small hemothorax and an ipsilateral hemidiaphragmatic ipomobility coexist, and the pulmonary curtain motion is reduced. ese are hypoventilation signs related to pain and traumatic
splinting of the thoracic cage and, as such, they tend to decrease rapidly after treatment with
analgesic and respiratory support.
Up to half of patients with chest trauma develops infectious complications97. e diagnosis
of infection is difficult because patients with chest trauma already show pulmonary opacities
and abnormalities in blood gases. In addition, the systemic inflammatory syndrome of trauma
is similar to the infectious findings. Pneumonia causes the appearance of new consolidations
or delay the clearance of contusive consolidation, so daily careful ultrasound monitoring of
parenchymal traumas may play an important role in recognizing changes otherwise unnoticed.
Gram-positive organisms such as S. aureus, streptococci and H. influenza cause the early
pulmonary infections. After two to four days, airways are colonized with hospital flora consisting of Gram-negative enteric bacteria and Pseudomonas spp. Prophylactic antibiotics may
select germ line, while an aggressive bronchial toilet is extremely useful in reducing this risk.
e interaction at level of the pulmonary capillaries between neutrophils and endothelium
is the basis for the development of lung inflammation, clinically expressed as ARDS. e
final event, pathologically decisive, is the decrease in lung compliance and oxygen diffusion
capacity. Ultrasound diagnosis of ARDS is described in a specific chapter. ARDS complicating a pulmonary contusion in ultrasound appears as bilateral inhomogeneous diffusion of
alveolar-interstitial syndrome, new gravitational consolidations and/or lack of resolution of
the existing ones.
Historically, limiting the accumulation of extravascular water in contused lungs or, more
generally, in the lungs of patients with systemic inflammation, has been one of the main
strategies adopted in chest trauma98. e evidence that SIRS, present and active in trauma,
causes pulmonary capillary permeabilization inducing a “local” pulmonary edema99, however
has corrected this concept. erefore, the hemodynamic objective in chest trauma is currently
the achievement of euvolemia. is condition, especially in the face of kidney and heart
failure, is rather difficult to achieve.
oracic trauma 295
Euvolemia, fluid responsiveness, preload, inotropy, pulmonary edema and serous collections
are all echographic targets. eir synthetic ultrasonic representation lies in the inferior vena
cava and its respiratory dynamics (even after postural changes), in the liquid content in the
serous cavities, in cardiac systolic function, in stroke-volume, and in the presence and severity
of interstitial lung disease (wet lung).
Finally, the accumulation of bronchial secretions is a major problem of the chest injured
patient. ey lead to variously dimensioned atelectasis according to the level of bronchial
obstruction. is causes hypoxemia, reduction of compliance and post-obstructive infections.
Consolidations with a residual aeration that is rapidly and progressively shrinking, or consolidation without air and with fluid bronchograms are the characteristic picture of atelectasis.
e treatment of obstructive atelectasis is based on the control of pain (which increases the
expulsion of mucus by coughing), and on a timely and accurate bronchial toilet. Resistant
forms can take advantage of bronchoscopy. Bronchial unblocking produces a prompt recruitment of collapsed regions, clearly visible on ultrasound.
➣ Trauma of the heart and great vessels
Despite an injury of the heart and great arteries (in particular the origin of the descending
aorta) is rare in blunt trauma, its immediate and late severity imposes an early diagnosis.
Heart and vascular injuries in penetrating trauma of the chest are more frequent, affecting
the area between the mammillary lines (heart box) or through the mediastinum. e importance of a prompt diagnosis of these lesions has acquired a practical sense when FAST has
incorporated the cardiac subcostal window for the immediate evaluation of the pericardium
in the injured patient.
Blunt and penetrating traumas will be described separately.
Closed mild cardiac lesions (contusions) are probably common in anterior chest traumas and
generally go unnoticed. Serious injuries, although much less frequent, are characterized by a
high mortality and therefore require early detection.
From a clinical point of view, closed cardiac lesions can be divided into acute and subacute.
Acute lesions are frequently catastrophic and usually require surgical treatment (rupture of
the cardiac chambers, cardiac tamponade, cardiogenic shock from severe contusion of the
heart). Subacute lesions shows arrhythmia and/or hemodynamic alterations (cardiac contusion, pericardial effusion, myocardial infarction, valvular damage, mural thrombus, and
intracardiac shunts).
In emergency and at bedside a heart ultrasound allows to recognize the signs of hemopericardium and tamponade, described in specific chapters.
To run in the examination of the heart, the operator does not have to be limited to perform
exclusively subcostal scans, since adequate cardiac images are not always guaranteed. Properly
cardiac scans are recommended. ey are able to confirm kinetic abnormalities, rupture of
the heart chambers (rare), valvular lesions (mainly of the aortic and mitral valves), haemopericardium and mural thrombosis.
Cardiac contusion is quite common in chest trauma, with an incidence between 8% and 71%
depending on the classification criteria. A number of recommendations for patients with possible myocardial contusion were published
100
. Table 5 summarizes the EAST recommendations.
296 oracic ultrasound
Table 5 – EAST recommendations for closed heart trauma
Level I Level II Level III
• If a closed heart trauma is
suspected, an ECG should
be performed at the
admission
• If ECG is altered (arrhythmias,
ST-T abnormalities, ischemia,
blocks), the patient should
undergo continuous ECG
monitoring for 24-48
hours. In the absence of
electrocardiographic anomalies
there is little or no risk of
significant injuries.
• In case of hemodynamic
instability, echocardiography is
appropriate. If the transparietal
echocardiogram is not
satisfactory, a transesophageal
echocardiogram should be
performed.
• The existence of sternal
fractures does not
predict the presence of
myocardial contusion
and does not necessarily
indicate monitoring.
• The troponins are not
useful for predicting
which patients develop
complications from
closed BCI.
Table 6 – Radiographic signs suggesting aortic injury
Widening of the mediastinum
Loss of aortic contour (funny looking mediastinum)
Deviation to the right of the trachea
Occlusion of the aortopulmonary window
Lowering the left main bronchus
Deviation of the esophagus (nasogastric tube) to the right
Expansion of paraspinal interfaces
Presence of pleural or apical caps
Left hemothorax
Fractures of the first two coasts or scapula (finding uncertain)
Only 10% of the lesions of
the intrathoracic great vessels
is caused by blunt trauma.
e aortic trauma is the most
frequent
101
and frequently it is
a deceleration injury localized
immediately downstream of
the left subclavian artery. It is
linked to significant kinetic
energies (road traffic accidents,
falls from height, explosions,
crushing etc.). Traumatic aortic rupture is usually fatal and
cause 10-15% of deaths from
road accidents, the majority
(85-90%) before the patient can get to the hospital. e radiographic signs of injury to the
intrathoracic great vessels are listed in Table 6.
CT angiography allows to view periaortic hematoma, pseudoaneurysm of the aortic arch,
deformation of the vessel, intimal flaps, clots and contrast extravasation (blush). e current
devices allow to better define the aortic lesions through multiplanar and volumetric reconstructions
102-104
. For assessing these injuries transthoracic ultrasound does not have a defined
role and allow finding only indirect signs (haemopericardium, hemothorax).
Penetrating cardiac injuries are rarer and are mainly observed in large Trauma Centers. e
clinical manifestations of penetrating cardiac injuries ranges from severe hemodynamic instability with cardiac arrest to minor signs. Cardiac tamponade is the main cause of shock in
these cases. Beck’s triad (muffled heart sounds, jugular venous distention, and hypotension)
characterizes this type of patients with a significant pericardial effusion. e inspiratory swelling
oracic trauma 297
of the jugular veins (Kussmaul sign) is another sign of tamponade. However, it is estimated
that the classic Beck’s triad is present in only 10% of patients with pericardial hypertension
105
Echocardiography is the gold standard in penetrating cardiac trauma for the diagnosis of
hemopericardium and tamponade. Precordial or subcostal ultrasound of the pericardium occupied by blood gives the surgical indication for the risk of tamponade, and makes a cardiac
injury or an injury of intrapericardial vessel likely
106
.
Rozicky analyzed with echography 209 patients with penetrating, precordial or transmediastinal trauma, showing a sensitivity and specificity of respectively 100% and 97% for the
presence of haemopericardium
current evidence
108,109
.
107
. ese data confirmed previous studies and represent the
Figure 38 shows a decision algorithm for the use of ultrasound in an integrated diagnosis in
penetrating injuries of the chest. Many of these situations are assessed by ultrasound and their
description is partly available in the section on echocardiography. erapeutic implications
are found in the section on echo-guided resuscitation.
e assessment of an echo-perceptible residual cardiac activity is extremely useful. In trauma, it represents an extreme chance of survival in the face of heroic interventions, such as
thoracotomy in the Emergency Room. A recent work by Moore
PENETRATING CHEST INJURY
Vital signs in DEU
110
, reiterates the futility of
NO
.
YES
Evaluable pulse and
pressure
FAST
No
hemoperitoneum/
hemopericardium
PNX
Figure 38 – Decision algorithm for the use of ultrasound in an integrated diagnosis in penetrating
injuries of the chest.
Chest us or extended FAST
Hemothorax | Hemopericardium
YES
Specific therapy
Circulatory arrest
Tamponade
Therapy
Stop resuscitation
Echocardiography
NOYES
Cardiac activity or residual
cardiac motion
ATLS, resuscitation,
thoracotomy
NO
YES
298 oracic ultrasound
thoracotomy when a cardiopulmonary resuscitation without response takes longer than 10
minutes after blunt trauma, more than 15 minutes after penetrating trauma and whenever
asystole is manifested.
[For a more detailed description of these topics, the reader is referred to the works cited in the bibliography,
from item 111 to item 123.]
➣ Diaphragmatic injuries
Roughly 1-5 % of patients with trauma has a diaphragmatic injury that chest X-ray can diagnose only in 28-64% of cases
124,125
. Often diaphragmatic injuries from blunt trauma are not
recognized for more than 24 hours or until serious complications arise from strangulation of
viscera. Chest radiography may show asymmetry in the position of the hemi-diaphragms or,
more definitively, the presence of hollow viscera in a hemithorax, with or without hemo- or
pneumothorax. Unfortunately, the axial arrangement of the diaphragm and the complex
distinction between diaphragm and liver have made the diagnosis difficult even with CT
126
ese limitations, however, are improved by the ability to reconstruct high-resolution CT images according to coronal and sagittal planes (sensitivity 70-100% and specificity 75-100%)
Echography was recommended by Ammann
128
, however ultrasound is not a simple and
127
sensitive method because of the air artifacts of colon and stomach and the presence of
subcutaneous emphysema. Moreover, a transabdominal view is not always optimal for the
diaphragmatic domes.
e direct sign of rupture is the presence of a diaphragmatic gap, which involve the abdominal
viscera protruding into the chest. We believe that thoracic scans at diaphragmatic level can
improve these diagnoses, showing most clearly the curvilinear echogenic line of the hemi-diaphragms, especially when contrasted by a pleural effusion (frequent) and/or hemoperitoneum.
In case of a valid acoustic window caused by pleural blood, it can be quite obvious to visualize stomach or spleen in endothoracic position, or the “naked” surface of the hepatic dome
through an opening in the diaphragm
129
. It is important to keep in mind that voluminous
diaphragmatic hernias of the abdominal viscera are almost never acute findings.
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