Diagnosing Pneumothorax with Ultrasonography

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Radiología. 2014;56(3):229---234

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RADIOLOGY THROUGH IMAGES

ଝ

Diagnosing pneumothorax with ultrasonography

∗

A. Lasarte Izcue , J.M. Navasa Melado, G. Blanco Rodríguez,

I. Fidalgo González, J.A. Parra Blanco

Servicio de Radiodiagnóstico, Hospital Universitario Marqués de Valdecilla, Santander, Spain

Received 15 May 2012; accepted 7 September 2012

Available online 11 June 2014

KEYWORDS Abstract The ultrasonographic diagnosis of pneumothorax is based on the analysis of artifacts.

Pneumothorax; It is possible to conﬁrm or rule out pneumothorax by combining the following signs: lung sliding,

Lung; the A and B lines, and the lung point. One fundamental advantage of lung ultrasonography is its

Chest; easy access in any critical situation, especially in patients in the intensive care unit. For this

Ultrasonography; reason, chest ultrasonography can be used as an alternative to plain-ﬁlm X-rays and computed

Diagnosis tomography in critical patients and in patients with normal plain ﬁlms in whom pneumothorax

is strongly suspected, as well as to evaluate the extent of the pneumothorax and monitor its

evolution.

PALABRAS CLAVE Diagnóstico ecográﬁco del neumotórax

Neumotórax;

Pulmón; Resumen El diagnóstico ecográﬁco del neumotórax se basa en el análisis de artefactos. Com-

Tórax; binando los siguientes signos: el deslizamiento pulmonar, las líneas A y B, y el punto pulmonar,

Ecografía; es posible diagnosticar o descartar de forma segura la presencia de un neumotórax. Una ven-

Diagnóstico taja fundamental de la ecografía pulmonar es su fácil acceso en cualquier situación crítica,

especialmente en pacientes en la UCI. Por ello, la ecografía torácica podría utilizarse como

alternativa a la radiografía simple y la TC en el paciente crítico, en pacientes con alta sospecha

de neumotórax y radiografía normal, y para valorar la extensión del neumotórax y monitorizar

su evolución.

Introduction

ଝ The utility of a simple thoracic X-ray and CT in the

Please cite this article as: Lasarte Izcue A, Navasa Melado J,

study of pneumothorax is very well deﬁned but in some

Blanco Rodríguez G, Fidalgo González I, Parra Blanco J. Diagnóstico

cases---especially in patients in a critical condition thoracic

ecográﬁco del neumotórax. 2014;56:229---234.

∗ X-rays are hard to interpret and in many occasions these

Corresponding author.

patients cannot go to the CT room. It is under these

E-mail address: [email protected] (A. Lasarte Izcue).

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230 A. Lasarte Izcue et al.

circumstances that the thoracic ultrasound is a useful sternum, the clavicle and the anterior axillary line---that is

alternative. Also it is an accessible cheap and innocuous divided into 4 quadrants. The ‘‘lateral area’’ is limited by

technique. the anterior and posterior axillary lines---that is divided into

Several studies have proven that in order to diagnose 2 quadrants.

pneumothorax the pulmonary ultrasound of the bedhead

of patients is as efﬁcient or even more efﬁcient than the

conventional X-ray performed when the patient is in Ultrasound ﬁndings of pneumothorax

1 --- 3

the supine position. Gas molecules produced in the lung

cause some sort of dispersion in the sound waves emitted by Several signs have been described for the echocardiograph-

the transducer in inﬁnite directions which in turn makes the ical diagnosis of pneumothorax. In our experience the

formation of diagnostic images just impossible. However following three (3) signs are the ones with the top diagnostic

they cause a series of artifacts whose analysis we can use utility:

to conﬁrm or discard pneumothorax. As a matter of fact

evaluating one pneumothorax through an ultrasound is

nothing but a study of artifacts. Lung sliding

Our goal is to describe the main ultrasound signs of pneu-

mothorax, consider its practical clinical applications and The limit between the visceral pleura and the surface of

recognize the possible limitations of this modality. lungs is visible in the ultrasound as an echogenic line---pleural

line. Lung displacement in the thoracic cavity during respi-

ration causes one alteration in the pleural line called ‘‘lung

Technical issues

sliding’’ (video 1).

One high frequency lineal probe (5---12 MHz) of one con-

ventional ultrasound scanner is enough for the analysis of

pleural line---which is superﬁcial. The lower-frequency con-

We must remember that lung sliding excludes pneu-

vex sound waves ( 2 --- 5 MHz) will be used to evaluate the

mothorax with a negative predictive value and a

subjacent pulmonary artifacts toward the pleural line. Pul- 4

sensibility of 100%. However its absence (video 2)

monary patterns are dynamic so the retrospective analysis

is not a synonym of pneumothorax. In patients in

of static images is not adequate. This is why the main signs

critical condition with massive atelectasis, intubation

are shown in video.

of the main bronchus, pulmonary contusion, chronic

The patient is often in the supine position and the pleura

obstructive pulmonary disease (COPD), acute respi-

are identiﬁed through one intercostal space. In an attempt

rator distress syndrome or pleural adherences, lung

to carry out the most possible systematic study it is advisable 5,6

sliding can or cannot be seen. This is why the absence

to divide each hemithorax into various areas and quadrants

of a sign of lung sliding needs to be combined with other

as shown in Fig. 1. The ‘‘anterior area’’ is limited by the

signs if we want to improve the diagnostic efﬁciency of

this test.

Lines A and B

Lines A are the result of a reverberation artifact that trans-

lates into the appearance of several lines that run parallel

to pleural lines at regular intervals.

We must remember that lines A can be seen both

in the usually well-aired lung and in the pneumothorax

(Fig. 2). The difference between one and the other is

the presence of the absence of the sign of lung sliding.

Figure 1 Systematic study by quadrants of one patient in the 8

Lichtenstein et al. have described a sensibility of 100%

supine position. Both the anterior and posterior axially lines

and a speciﬁcity of 96% when lines A and the absence

mark out the anterior and lateral areas which are in turn divided

of the sign of lung sliding are combined (video 3).

into 6 quadrants. Anterior area: Quadrants 1 to 4. Lateral area:

Quadrants 5 to 6. Since there is a tendency for free air to accu-

mulate in the most elevated area we started our study by the

Lines B are a comet tail artifact produced in the pleural

intersection made up of the 4 anterior quadrants. If we wish

line at the contact zone between the visceral pleura and the

to do a complete exam each one of the 6 quadrants need to be

2,10

usually well-aired lung. Lines B can be seen separately in

analyzed. Doing one systematic analysis it is possible to identify

the normal lung (Fig. 3) and its number goes up in cases of

most pneumothoraces. AAL: Anterior axillary line; PAL: Poste-

11---13

interstitial or alveolar affectation (Fig. 4).

rior axillary line.

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Diagnosing pneumothorax with ultrasonography 231

We must remember that its importance lies in that

this artefact excludes pneumothorax.

Figure 3 Line B. Sixty-one-year-old male who had previously

undergone a lung biopsy of his right hemithorax. Ultrasound

control 3 h later to discard pneumothorax. One line B (arrow)---

perpendicular and synchronic to the movement of pleural line

(arrow head) shows a usually well-aired lung and allows us to

exclude pneumothorax. In normal people we usually see these

comet tail artifacts separately in the inferior-lateral thoracic

wall.

slowly slides into the inferior-lateral portion of the thorax

(Fig. 6 and video 5). Medially the lung sliding will be absent in

the area of pneumothorax. More laterally there will be lung

sliding where the visceral and parietal pleural leaves are still

in contact. Lung point will be identiﬁed as the intermedi-

ate point where lung sliding will be visualized intermittently

given that with the respiratory movement the collapsed lung

intermittently slides into the area of pneumothorax.

We must remember that the sign conﬁrms the pres-

14,15

ence of pneumothorax and it can also be used to

evaluate its importance. The more lateral and inferior

the lung point is to the thoracic wall the bigger it is.

Figure 2 Lines A. (A) ﬁfty-two-year-old male admitted in the One very posterior or absent lung point suggests a mas-

hospital Intensive Care Unit with a clinical presentation of right sive pneumothorax with complete lung actelectasis

pneumothorax after thoracic trauma. Lines A are reverberating and predicts the need for implanting a tube for pleural

16,17

artifacts seen as horizontal lines (arrows) stemming from pleural drainage.

line (arrow head) and set in irregular intervals. (B) Forty-three-

year-old healthy woman showing lines A (arrows) in a breast

control ultrasound set in regular intervals below the pleural line

(arrow head). In healthy people we can see these reverberating

Clinical applications

artifacts with no pathological meaning as a consequence of a

usually well-aired lung. The asterisk represents the rib from

Now we will take a look at the clinical situations in which in

intercostal space with its acoustic shadow.

our opinion the thoracic ultrasound can have a major role in

the diagnosis of pneumothorax.

Lung point

Unstable patients

It is the point where visceral and parietal pleural leaves

separate. It is a dynamic image like the sign of lung sliding ICU patients are those who will beneﬁt the most from this

that contains ﬁndings of well-aired lung and pneumothorax technique which in turn is possibly the main clinical appli-

(Fig. 5 and video 4). To ﬁnd the lung point the transducer cation.

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232 A. Lasarte Izcue et al.

We must remember that in extremely urgent cases

the ultrasound can replace the handheld portable con-

ventional X-ray in the diagnosis of pneumothorax and

it can also be used as a guide for the implantation of

a drainage tube. The more critical the emergency, the

easier the echographical signs on which the diagnosis

should be based. This is why in unstable patients with

thoracic pain, dyspnea and timpanism one echographi-

cal pattern with no sign of lung sliding with lines A and

without lines B will lead to the implantation of a tube

16---18

for pleural drainage.

Hidden pneumothorax

The handheld portable conventional X-ray is some times

hard to interpret and frequently it is not possible to diag-

nose the presence of pneumothorax. These cases of hidden

pneumothorax are important since they can be the prod-

uct of hemodynamic instability. In polytraumatized patients

requiring invasive ventilation or air transport the presence

of pneumothorax needs to be discarded. Similarly in stable

patients a small hidden pneumothorax modiﬁes the criteria

of follow-up, prognosis, and observation in the emergency

room.16

The percentage of collapsed lung is a major criterion to

decide whether to implant a drainage tube or administer

conservative therapy. The guidelines for the management

of pneumothorax quantify its volume based on the dis-

tance between parietal and visceral pleura in the PA thorax

plaque (Table 1). With ultrasound ﬁnding the lung point

helps us quantify the extension of pneumothorax and pre-

14---17,22

dicts the need to implant a tube for pleural drainage.

Pneumothorax monitorization

In our own experience with a series of 35 patients who

underwent ultrasound after one CT guided-aspiration punc-

ture that proceeded with a thin lung needle, 100% of the

23 3

pneumothorax could be correctly diagnosed. Sartori et al.

suggest that lung ultrasound can be the elective method to

exclude, diagnose, and monitor the pneumothorax after lung

post-biopsy---all guided by ultrasound. It can also be used to

monitor the retraction of the thoracic tube and assess the

persistence or not of the pneumothorax.

Possible errors and limitations

Figure 4 Lines B. (A) Sixty-nine-year-old male. Thoracic

ultrasound shows irregularity in the echogenic pleural line that

The thoracic ultrasound has a high negative predictive value

is interrupted due to lung mass with pleural extension. The

in the detection of pneumothorax. The positive predictive

numerous lines B (arrows) are due to the fact that ultrasonic

value is somehow inferior since we can have coexisting con-

waves are transmitted through the pathological interstitium.

ditions that complicate the echographical exam while giving

1 Its presence discards pneumothorax. (B) Forty-eight-year-old

false positives. The subcutaneous emphysema (Fig. 6),

woman with known affectation of lung interstitium in whom

pleural calciﬁcations or one patient with poor acoustic trans-

4,14,18 we can see multiple lines B (arrows) secondary to the presence

mission can all or complicate the diagnosis. In patients

of interstitial liquid. Because they are born from the surface

with dyspnea, COPD, and pleural adherences lung sliding

5,6 of visceral pleura the importance of lines B is that its presence

can be diminished or abolished. This sign can be the

indicates the expansion of the lung.

only ﬁnding enabling us to distinguish a pneumothorax from

8,25

a big pleural bulla. Other possible limitations include

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Diagnosing pneumothorax with ultrasonography 233

Table 1 Comparison between the deﬁnition and the recommended therapy from the most important clinical guidelines on

‘‘large’’ pneumothoraces.

Guidelines Deﬁnition of large pneumothorax Recommended therapy

ACCP >3 cm of apical interpleural distance Intercostal drainage tube

BTS Presence of a visible space >2 cm between lung Aspiration

and thoracic wall

BSP Presence of a pleural space along the whole of the Aspiration or implantation of a small

lateral thoracic wall thoracotomy catheter

ACCP: American College of Chest Physicians; BSP: Belgian Society of Pulmonology; BTS: British Thoracic Society.

pneumothoraces restricted to mediastinal area or posterior

pneumothoraces as well as limitations from the curve of learning.

Conclusions

Despite lung ultrasound for the diagnosis of pneumothorax

has been largely disregarded its practical utility has been

conﬁrmed. In our experience it is a fast, highly sensible non-

invasive tool with a short curve of learning. Critical patients

are the ones who will beneﬁt the most from this modal-

ity. However if experienced in the use of this modality lung

ultrasound can also be useful for the monitorization of pneu-

mothoraces after lung post-biopsy and assessment of the

retraction of pleural tube.

Figure 5 Lung point. Seventy-two-year-old male who had pre-

Ethical responsibilities

viously undergone a lung biopsy due to the presence of a mass in

his left lung. The ultrasound 3 h after puncture shows the lung

Protection of humans and animals. Authors conﬁrm that no

point (arrow) through an intercostal space (asterisk: ribs) con-

experiments have been done with humans or animals during

ﬁrming pneumothorax. The limit between the well-aired lung

this research.

and the pneumothorax (lung point) can be seen as a disruption

of pleural line (arrow head)---which in turn seems irregular and

thickened. Conﬁdentiality of data. Authors conﬁrm that the pro-

tocols of their centers have been followed on matters

concerning the publishing of data from patients. They

also conﬁrm that all patients included in this study have

been given enough information and handed over their

written informed consent for their participation in this

study.

Right to privacy and informed constent

Authors conﬁrm they have been given the written informed

consent from patients and/or individuals included in this

article. This paper is owned by its author of correspondence.

Authors

Figure 6 Location of lung point. CT-image of a polytrau- 1. Manager of the integrity of the study: ALI and JAPB.

matized patient with a large right pneumothorax and a small 2. Original Idea of the Study: ALI, JMNM, GBR, IFG and

anterior and left posterior pneumothoraces. The arrows show JAPB.

the theoretical movement of the ultrasound probe toward the 3. Study Design: ALI, JMNM and JAPB.

thoracic lateral wall in search for the lung point. The long arrows 4. Data Mining: ALI, JMNM, GBR, IFG and JAPB.

are showing the lung point in the lateral thoracic wall while pre- 5. Data Analysis and Interpretation: ALI, JMNM and JAPB.

dicting the extension of pneumothorax. Note the subcutaneous 6. Statistical Analysis: NA.

left emphysema that could prevent or complicate an adequate 7. Reference Search: ALI, IFG and JAPB.

ultrasound access. 8. Writing: ALI and JAPB.

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234 A. Lasarte Izcue et al.

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