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130 oracic ultrasound
31. Remerand F, Dellamonica J, Mao Z et al. Multiplane ultrasound approach to quantify pleural effusion
at the bedside. Intensive Care Med 2010; 36: 656-664.
32. Goecke W, Schwerk WB. Die Real-Time-Sonographie in der Diagnostik von Pleuraergüssen. In:
Ultraschalldiagnostik 89 (Gebhardt J, Hackelöer B-J, Klinggräff G, Seitz K, eds.). Springer, Berlin-HeidelbergNew York-Tokio, 1990.
33. Jen Yu C, Yang PC, Chang DB, Luh KT. Diagnostic and therapeutic use of chest sonography: value in
critical ill patients AJR 1992; 159: 695.
34. Tsai TH, Yang PC. Ultrasound in the diagnosis and management of pleural disease. Curr Opin Pulm
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35. Gorg C, Restrepo I, Schwerk WB. Sonography. Sonography of malignant pleural effusions. Eur Radiol
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36. Maslove DM, Chen BT, Wang H, Kuschner WG. e diagnosi and management of pleural effusions in
the ICU. J Intensive Care Med 2011; 11 [Epub ahead of print].
37. Mattison LE, Coppage L, Alderman DF et al. Pleural effusion in the medical ICU: prevalence, causes,
and clinical implications. Chest 1997; 111: 1018-1025.
38. Light RW, Girad WM, Jenkinson SG et al. Parapneumonic effusions. Am J Med 1980; 69: 507-512.
39. Volpicelli G, Frascisco M. Lung ultrasound in the evaluation of patients with pleuritic pain in the emergency department. J Emerg Med 2008; 34: 179-186.
40. Gehmacher O, Kopf A, Scheier M et al. Can pleurisy be detected with ultrasound? Ultraschall Med
1997; 18: 214-219.
41. Marks WM, Filly RA, Callen PW. Real time evaluation of pleural lesions: new observations regarding
the probability of obtaining free fluid. Radiology 1982; 142: 163-164.
42. Wu RG, Yuan A, Liaw YS et al. Image comparison of real time gray scale ultrasound and colour Doppler
ultrasound for use in diagnosis of minimal pleural effusion. Am J Respir Crit Care Med 1994; 150: 510-514.
43. Kuhlman JE, Singha NK Complex disease of the pleural space: radiographic and CT evaluation.
Radiographics 1997; 17(1): 63-79.
44. Meirelles GS, Kavakama JI, Jasinowodolinski D et al. Pleural plaques in asbestos-exposed workers: reproducibility of a new high-resolution CT visual semiquantitative measurement method. J orac Imaging
2006; 21(1): 8-13.
45. Görg C, Bert T, Görg K. Contrast-enhanced sonography for differential diagnosis of pleurisy and focal
pleural lesions of unknown cause. Chest 2005; 128: 3894-3899.
46. Foran P, Colleran G, Madewell J, O’Sullivan PJ. Imaging of thoracic sarcomas of the chest wall, pleura,
and lung. Semin Ultrasound CT MR. 2011; 32: 365-376.
47. Goerg C, Schwerk WB, Goerg K et al. Pleural effusion: an “acoustic window” for sonography of pleural
metastases. J Clin Ultrasound 1991; 19: 93-97.
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➤ Updated bibliography
Smargiassi A, Inchingolo R, Zanforlin A, Valente S, Soldati G, Corbo GM. Description of free flowing
pleural effusions in Medical reports after echographic assessment. Respiration 2013.
A standardized semiquantitative grading method for evaluating pleural effusions. It proposes six grades, and takes
in account lobar collapse entity and the intercostal spaces involved.
Pathology of the pleura 131
Sachdeva A, Sheperd RW, Lee HJ. oracentesis and thoracic ultrasound: state of the art in 2013. Clin
Chest Med 2013;34:1-9.
A contemporary review on thoracentesis and the use of ultrasound in chest medicine.
Bugalho A, Ferreira D, Dias SS, Shuhmann M, Branco JC, Marques Gomes MJ, Eberhardt R. e diagnostic
value of transthoracic ultrasonographic features in predicting malignancy in undiagnosed pleural effusions:
A prespective observational study. Respiration 2014.
Ultrasound morphological features (pleural/diaphragmatic nodules and pleural/diaphragmatic thickness > 1 cm)
can aid in differentiating neoplastic from non-neoplastic effusions. Lung air bronchograms and a septated pattern
of the effusion are more common in non neoplastic effusions.
6
Pneumothorax
Pneumothorax (PNX) is the accumulation of air in the pleural cavity1.
2
It can be spontaneous
iatrogenic and therapeutic events, or related to specific diseases
, caused by traumatic (traumatic PNX), surgical,
3
. Primary
spontaneous pneumothorax occurs without apparent cause, in the
absence of widespread pathology of the lung or emphysematous macroscopic bubbles. It is more frequent in 30-40 year-old thin and asthenic
males. Most of these PNX are not really primary, but their causes, albeit
modest and focal (e.g. apical), are related to lung pathology (e.g. small
emphysematous bubbles).
Secondary spontaneous pneumothorax occurs without an evident cause,
but in the presence of lung disease. It complicates chronic obstructive
pulmonary pathology (emphysema, asthma) or granulomatous diseases
such as sarcoidosis or tuberculosis. Tumors, pulmonary abscesses or
fibrosis can cause PNX.
Finally, iatrogenic PNX is common and occurs after procedures like
4
thoracentesis
opsies or mechanical ventilation
, central venous cannulation, pleural and pulmonary bi-
5
.
Table 1 shows a classification of PNX (from Sabiston).
Table 1 – Classification of PNX
Spontaneous Traumatic Iatrogenic Other causes
Primary
Secondary
Copd
Bullous disease
Cystic fibrosis
Pneumocystis related
Congenital cysts
Idiopathic fibrosis
Pulmonary embolism
Catamenial
Neonatal
Modified from: Townsend C, Beauchamp RD, Evers BM, Mattox K.
2007.
Penetrating
injuries
Blunt trauma
Thoracentesis
Mechanical ventilation
Venous catheterization
Lung biopsy
Post-surgical
Sabiston Textbook of Surgery.
Boerhaave’s syndrome
Saunders,
133
134 oracic ultrasound
From the pathophysiological point of view, PNX results in alterations of vital functions in
relation to its volume. It compresses the lung tissue and mediastinal structures, reducing lung
compliance and ventilatory volumes. e pre-existing situation of lung tissue also affects the
severity of symptoms.
When the entry of air into the pleural cavity is progressive and irreversible, hypertensive PNX
is the result. It is a life-threatening situation due to compression of the lung parenchyma
and the lateral shift of the mediastinum, with obstruction of the venous return to the heart.
In this chapter general, radiological and echographic characteristics will be detailed. Clinical
and diagnostic aspects of secondary traumatic PNX will be described in a separate chapter.
➣ Diagnosis of PNX
Dyspnea, pleuritic pain and hypoxemia are indicative of PNX. ese signs and symptoms are
all variably expressed in relation to the size of the organ collapse and its underlying pathology6. A ventilated and sedated patient does not show symptoms that may raise suspicion,
with sudden sometimes dramatic clinical situations.
e reduction or abolition of breath sounds with increased thoracic resonance, caused by the
presence of air in the pleural cavity, are typycal signs. In case of hypertensive PNX, shock with
venous hypertension and jugular venous distention occurs. However, if the lung collapse is
less than 25% and the subject is healthy, respiratory symptoms may be absent.
e radiological diagnosis of PNX7 is easy if it is large and the chest X-ray is well executed
(in the upright position and maximum expiration). It is clear if lung collapse reaches such a
degree as to determine a radiolucent airspace, that separates the visceral pleural line from the
parietal pleura. In these cases, the lung interstitium and especially the vascular images reach
the parenchymal limit but are not visible beyond it8.
In other cases, the diagnosis may be more difficult, especially when the degree of lung collapse
is lower and when X-ray is performed on a supine patient9 (Figs. 1-2).
Figure 1 – Patient with left PNX not detected by X-ray.
Pneumothorax 135
CHEST
Figure 2 – Chest CT of the same patient with minimal anterior PNX.
Sometimes the radiographic demonstration of the deep sulcus sign may be helpful. It is represented by a relatively radiolucent area in the juxtacardiac region, adjacent to the diaphragm
and extending to the lateral costophrenic sinus. Deep sulcus sign is due to pleural air located
at the bottom and side of the hemithorax
Figure 3 – Minimal right PNX. To the left, in CT, minimal parasternal air collection. To the right, the
X-ray is not easily interpretable, although a faint diaphany can be detected in the cardiophrenic right
angle. Occult or undiagnosed PNX?
10,11
(Fig. 3).
EXPIRATION
136 oracic ultrasound
In other cases hyperlucency of the upper abdominal quadrants or a supernormal visibility of
the anterior costophrenic sinus, appears. Otherwise radiolucent lines encircle the ipsilateral
mediastinal edge. In patients undergoing ventilation with positive pressure, a warning sign of
pneumothorax can be represented by the appearance of interstitial emphysema. It appears as
thin radiolucent striae or small bubbles along the bronchial vessels or in subpleural regions12.
In our experience, X-rays executed in poor conditions on supine patients, missed the diagnosis
of small PNX in 50% of cases (those not extending beyond the mediocoronal line). ese
PNX are classified as “occult” PNX (most often traumatic)
13,14
. eir recognition is important
especially if the patient has to undergo mechanical ventilation15.
Chest CT is the gold standard for this diagnosis. Chest CT scans, even without the use of
contrast agents, may show pleural air even in minimum quantities, if it is localized exclusively
in the front (Fig. 4). CT may also show emphysematous bubbles, which have a role in the
formation of PNX, and small pleural effusions are often associated with it in the late phase.
Liquid
Air
Lung
Figure 4 – Circumscribed PNX. CT detects two air collections in the right hemithorax, that represent air
confined in the intrapleural region by adhesions. The lung shows signs of interstitial disease. To the right,
ultrasound images obtained with linear probe of left hemithorax and in correspondence with a fluid level
in the right hemithorax. To the top, lung affected by interstitial disease. To the bottom, air placed on the
fluid collection.
➣ Echography in PNX
e low diagnostic accuracy of chest X-ray for detecting PNX, if performed as a single scan
on supine patient with little PNX, has turned the attention to the small undiagnosed intrapleural air collections (occult pneumothorax). is happens, as we shall see in a specific
chapter, especially in trauma patients. Small spontaneous occult PNXs, which often occur
in young subjects, may in fact not manifest, and a missed diagnosis may in many cases not
be problematic. Conversely, in subjects with already compromised pulmonary parenchyma,
even small PNXs, regardless of their evolutionary trend, may have a pathogenic weight for
the patient.
It is therefore desirable to perform accurate non-invasive investigations at the bedside in critical subjects. Many hemodynamically unstable patients, or subjects with signs of respiratory
Pneumothorax 137
distress or chest pain, may benefit from these investigations. In the case of trauma and in
non-traumatic contexts, a simple test that can fill the gap between conventional radiology
and diagnostic CT can be extremely useful. As it already happens in different fields, the use
of ultrasound represents an improvement of the physical examination.
Ultrasound diagnosis of PNX originates in veterinary medicine. In 1986, Rantanen described
the sonographic signs of pneumothorax in horses. “Pneumothorax is a straightforward ultra-
sound diagnosis […] a static gas reverberation artifact will be encountered dorsally […] the surface
will not glide. Where the lung touches the wall, the pleura will be seen moving”. It was basically
a synthetic list of signs, still valid today in humans (changing of course the word dorsally in
anteriorly or superiorly)16.
In PNX a variable amount of intrapleural air prevents display of the normal pleural movement,
that is replaced by fixed reverberations of air. e normal pleural sliding reappears again at
the edge of the air collection where the lung shows a parietal contact. By performing scans
above an intrapleural air collection, the fixed images obtained may resemble a normal pleura.
ey are actually the result of an absolute acoustic mirror, devoid of any interface movement
and irregularities17. erefore artifacts attributable to a normal pleura (various arrangements
of Lines B, white lung), can not be seen by performing scans over an intrapleural air collection. e best visibility of this difference can be detected in the scans that capture, in the
same image, the real pleura and the pure interface of an air collection. In these images lung
points are evident
18,19
.
Analysis of the literature shows that the absence of lung sliding has a sensitivity of 95% and
a specificity between 91% and 100% for the diagnosis of PNX. e presence of lung points,
a sensitivity of 66% and a specificity of 100%. e absence of B Lines, a sensitivity of 100%
and a low specificity. at means that lung points are pathognomonic of PNX and that the
presence of vertical artifacts has a high predictive power for the exclusion of PNX
20,21
.
Over time, other signs of pneumothorax were found, but they do not change at all the approach detailed above and are only variations of the same acoustic phenomena.
ese sonographic findings of PNX are listed in Table 2 (Fig. 5).
Table 2 – Sonographic findings of PNX
Absence of pleural movement against the chest wall (absence of sliding sign)
Linearization of “pleural line” and absence of vertical artifacts (B Lines)
Evidence of lung points
Step sign of the pleural line at the level of lung point. True pleural line appears slightly deeper
Disappearance (B Lines and white lung) and replacing these artifacts with pure reverberation
Loss of the acoustic window for pleural and parenchymal lesions, if previously visible (useful in case
of transparietal biopsies)
Air curtain sign in case of hydropneumothorax: the air-liquid level is like the bottom margin of a
curtain which, descending with inhalation, obscures any detail below
Air microbubbles in the liquid of hydropneumothorax
e absence of sliding sign has been previously treated22 and will be treated again in relation
to the traumatic pneumothorax. In small PNX, this finding must be sought when patients
are in the supine position, particularly in the chest regions of the deep sulcus area. Deep
138 oracic ultrasound
sulcus area is located on the anterior chest wall immediately adjacent to the inferior sternum
and on the skin correspondent to heart margins23. e examination should be extended to
all lung surfaces, including apices and regions obscured by overlying structures. is may be
problematic, especially in uncooperative patients.
Figure 5 – Ultrasound images that illustrate the appearance of air in the pleural cavity in the case of
hydro-or hemopneumothorax. In the supine position air places itself above the pleural fluid. In any case,
it appears as a mirror plane (with generation of reverberations) that is placed on the liquid which, in
turn, deviates the lung from the chest wall. In the images the large arrows indicate the air, the small ones
the pleural plane, while the dashed line indicates the position of the pleural line behind the artifacts.
In PNX, over a more or less extensive surface, the vision of the visceral pleura, with its small
irregularities and movements (sliding, lung pulse) is lost.
Each possible vertical artifact (B Lines) is deleted, since it originates from the immediate
subpleural lung parenchyma (see the section on interstitial syndrome) (Clips 1-5).
Clips 1, 2, 3, 4 – Examples of PNX where no sliding sign or B Lines are
observed. In Clip 2 the absence of curtain at basal level is evident. In Clip 4
pleural sliding is absent, but the presence of a B Line categorically excludes
the pneumothorax.
Clip 5 – Presence of lung point. Step sign (the small “step” between the lung
pleura and the air artifact determined by PNX) is observed.
In the literature, the utility of the M-Mode for the diagnosis of PNX has been stressed. It
allows to see the aerated lung moving along with the breath (“seashore sign”), while above the
PNX air collection horizontal echoes are evident (“stratosphere sign”)24 (Figs. 6-9).
Pneumothorax 139
Wall
Pleura
Lung
Figure 6 – Image obtained with M-mode method, where the pleural sliding is graphically evident
“seashore sign”).
Wall
Pleura
Lung
Figure 7 – Image similar to the previous one, in the case of PNX. The absence of pleural sliding
determines, in M-Mode, the appearance of linear regular echoes (“sign of the stratosphere”).
SEASHORE SIGN
SIGN OF THE STRATOSPHERE
Figure 8 – M-Mode representation of lung point.
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