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34 Eusion
421
Fig. 34.3 In order to
perform quantication
of pleural uid using the
Balik or similar
formulas, the transducer
probe must be rotated 90
degrees (a) in order to
measure the distance
between the parietal and
visceral pleura as
visualized similar to
axial CT imaging (b). In
the case of the Balik
formula, the maximal
end-expiratory distance
between parietal and
visceral pleura (Sep) is
used in the equation:
pleural effusion volume
(mL)=20×Sep (mm).
Courtesy of Catherine
Cichon, MD
a
b
pleural uid, is whether or not the collection represents an empyema, as early source control with
chest tube placement is crucial. In a study of 94
patients with fever and a pleural effusion, 118
diagnostic thoracentesis were performed and 15
empyemas were identied [11]. There were no
422
ab
cd
N. A. Leverone and D. A. Sweeney
Fig. 34.4 Pleural uid quality can be described along a
spectrum based on the complexity and heterogeneity of
the uid. Here you can see examples of anechoic (a),
complex nonseptated (b), complex septated (c), and com-
empyemas in cases in which the uid was either
anechoic (0/47 cases) or complex nonseptated
plex homogeneously echogenic uid (d). The characteristics of the visualized uid can lend to the differential, such
as anechoic uid almost never seen in patients with
empyema
Ultrasound toGuide
theManagement ofPleural Eusions
and relatively hypoechoic (0/36 cases). This
study strongly suggests that the diagnosis of an
empyema can be safely excluded in patients with
anechoic uid. Moreover, the authors demonstrated the value of serial POCUS exam to assess
pleural effusion characteristics. There were three
cases of empyemas in which the initial thoracentesis revealed sterile uid, but because these
patients remained febrile, a repeat thoracentesis
was performed and the diagnosis of an empyema
was made on a subsequent uid sampling. In
each of these cases, the ultrasound uid characteristics became more complex or more hyperechoic between the time the initial and repeat
thoracenteses were performed.
POCUS should be viewed as an additional, complementary imaging tool to chest radiography
(CXR) and chest computed topography (CT) in
the management of pleural effusions. The volume
of a pleural effusion is a factor in deciding whether
to place a chest tube; likewise determining if other
interventions such as diuretic therapy are effectively decreasing pleural effusion volume can also
be vital information to patient management.
Bedside ultrasound can answer both these, and
other clinical questions in relation to the pleural
space. POCUS can also rule out the presence of
an empyema when anechoic uid is present.
However, this does not obviate the need for repeat
34 Eusion
423
POCUS assessment of an effusion if such a patient
fails to improve, as changes in ultrasound imaging
can herald the development of an empyema.
Compared to free-owing pleural effusions,
there is greater uncertainty surrounding the optimal management of empyemas or complex parapneumonic effusions. Specically, there is some
controversy regarding the decision to treat these
effusions with chest tube placement and intrapleural brinolytic therapy, or instead proceed
directly to video-assisted thoracoscopic surgery
(VATS) [17]. While chest tube drainage combined
with intrapleural therapy is commonly used as the
initial approach for the treatment of complicated
pleural effusions, failure rates have been reported
to occur in up to 22–32% of cases [18, 19].
However, POCUS imaging could potentially aid
in determining the best initial management strategy for patients with empyemas. Loculations in
the form of septations are more readily visualized
using POCUS compared to CT, and the appearance of sonographic septations is predictive of the
outcome of simple catheter drainage for the treatment of empyemas and complicated parapneumonic effusions [20–26]. Additionally, analysis of
the pixel intensity of pleural uid ultrasound
images has been shown to correlate with the duration of the chest tube drainage, days until apyrexia, and total length of hospitalization [13].
Thus, it is possible that POCUS could have a
growing role in guiding the initial treatment of
loculated effusions in terms of whether to begin
with medical therapy or proceed directly to VATS.
Summary Points
• Lung ultrasound is an essential tool for identi-
fying, characterizing, and managing pleural
effusions in the critically ill patient.
• Ultrasound scanning of pleural effusion and
ultrasound-guided procedures can be per-
formed safely with the critically ill patient in
the supine position.
• Pleural effusions are common in the ICU and
their identication can be helpful in under-
standing the pathology of a critically ill
patient.
• Lung ultrasound is more sensitive than CXR
for identifying the presence of a pleural effu-
sion and can be used to estimate the volume of
an effusion.
• Ultrasound image characteristics aid in predicting whether a uid collection is exudative,
transudative, or may represent an empyema.
• Both the estimated size and the ultrasound
image characteristics of a pleural effusion can
be helpful in deciding whether to perform a
thoracentesis versus placing a thoracostomy
tube.
• While complicated pleural uid can be identied using bedside ultrasound this information
has not yet been shown to inform the decision
of whether to place a chest tube or proceed to
video-assisted thoracoscopic surgery.
Pro-Tips Call Outs
POCUS imaging has been shown to be remarkably sensitive for the detection of pleural effusions and volume is easily estimated either
quantitatively or qualitatively.
Recognize the importance of nding a spine
shadow cephalad to the diaphragm as this
unequivocally means there is pathology in the
chest cavity—lung atelectasis, consolidation, or a
pleural effusion.
Large effusions can be estimated using vari-
ous formulas or qualitative assessment.
In one well done study, the nding of only
anechoic uid ruled out the possibility of an
empyema.
Evolving Evidence
Dening the optimal management of complicated, loculated effusion has been elusive with
advocates for VATS versus chest tube being the
two primary options. Septations and debris can
be easily identied using POCUS. Ultrasound
characterization of pleural uid has the potential
to guide this initial management decision.
References
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13. Varsamas C, Kalkanis A, Gourgoulianis KI, Malli
F. The use of a novel quantitative marker of echo-
genicity of pleural uid in parapneumonic pleural
effusions. Can Respir J. 2020;2020:1283590.
14. Chian CF, Su WL, Soh LH, Yan HC, Perng WC,
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malignant pleural effusions in patients with malignancies. Chest. 2004;126(1):129–34.
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Point-of-Care Ultrasound
fortheDiagnosis ofPneumothorax
JoelTurner
35
Learning Objectives
1. Pneumothorax (PTx) is a potentially lifethreatening diagnosis in patients complaining
of chest pain and dyspnea.
2. Undiagnosed, pneumothorax can lead to signicant morbidity and mortality if not rapidly
managed accordingly.
3. Current methods of diagnosis, including
physical exam and chest X-ray, are insensitive
in identifying pneumothoraces.
4. Lung point of care ultrasound has been used
for over 15years for the accurate and rapid
bedside diagnosis of pneumothorax.
5. Lung ultrasound for the rapid diagnosis of
pneumothorax has diagnostic sensitivities
approaching those of CT.
6. By recognizing the presence or absence of
lung sliding, B-line artefacts, lung pulse, and
lung points, a trained user of POCUS can
detect or rule out pneumothorax within a few
minutes.
Supplementary Information The online version contains supplementary material available at https://doi.
org/10.1007/978- 3- 031- 80038- 2_35.
J. Turner (*)
Department of Emergency Medicine, Jewish General
Hospital, McGill University, Montreal, QC, Canada
Introduction
Dyspnea and acute chest pain are among the most
common, potentially dangerous, symptoms that
physicians are faced to diagnose on a daily basis.
While the differential diagnosis is extensive,
there are only a handful of potential diagnoses
which require rapid, accurate recognition. These
include acute myocardial infarction (AMI),
Pulmonary embolism (PE), acute exacerbation of
chronic obstructive lung disease (AECOPD),
Pneumonia, pericarditis, and of course
pneumothorax.
Pneumothorax occurs when air is introduced
into the pleural space. This can occur spontaneously, or following a traumatic event. In all cases,
depending on the size of the pneumothorax, pain
and respiratory difculty can ensue. However, if
the air within the pleural space is under positive
pressure, this results in a tension pneumothorax
which can quickly lead to cardiorespiratory collapse. A patient with a tension pneumothorax
requires urgent recognition and management.
Traditionally, the diagnosis of pneumothorax is
done through the combination of auscultation
and chest X-ray (CXR). Unfortunately, the literature has repeatedly shown that these modalities
are very poor at ruling out pneumothorax, which
can lead to signicant morbidity and/or mortality.
While computer tomography (CT) remains the
gold standard for pneumothorax diagnosis, it is
expensive, time consuming, and often not feasi-
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2025
M. J. Lanspa, A. T. Levinson (eds.), Echocardiography and Ultrasonography in the ICU,
Respiratory Medicine, https://doi.org/10.1007/978-3-031-80038-2_35
425
426
J. Turner
ble or readily available. Over the past 15years,
point-of-care ultrasound (POCUS) of the lung
has been shown to be signicantly more accurate
than exam ndings and CXR at diagnosing pneumothorax. As a result of this, along with it being
a rapid and safe test to perform, lung POCUS has
become an essential bedside tool to timely assess
the possibility of pneumothorax.
This chapter will review the current understanding of lung POCUS in the diagnosis of
pneumothorax. We will review the basic concepts
of lung sonography, discuss the techniques to
perform lung POCUS to rule out pneumothorax,
and review the ndings of the normal and pathologic lung.
Background
Pneumothorax is often classied based on its etiology. A primary spontaneous pneumothorax
(PSP) is dened as occurring without any precipitating event and in the absence of any known
lung disease. These are relatively common, tend
to occur in younger males (tall stature), with an
incidence that ranges between 34 and 52 cases
per 100,000 population [1, 2]. Secondary spontaneous pneumothorax (SSP) occurs as a result of
underlying lung disease, and is much more common in adults and in the elderly [3]. By far, the
most common cause of SSP is COPD, associated
with 50–70% of all cases [3, 4]. Other causes of
SSP include cystic brosis, lung malignancy,
interstitial lung disease, and necrotizing pulmonary infection.
Trauma is probably the most common overall
cause of pneumothorax. These can be caused by
either blunt, or more commonly penetrating
external trauma, or through iatrogenic mechanisms following an invasive procedure performed
in the hospital setting [5].
Iatrogenic pneumothoraces are an important
cause of pneumothorax, occurring more often in
teaching vs non-teaching hospitals [6]. The most
common procedure causing pneumothorax is
central venous catheterization (if venous access,
dialysis catheterization, transvenous pacemaker
insertion), followed by thoracentesis, and
mechanical ventilation-induced barotrauma.
Together, these three procedures account for
approximately 75% of hospital-acquired pneumothorax [7, 8].
Historically, the diagnosis of pneumothorax
starts with history and physical exam, followed
soon after by chest X-ray. In fact, it is still considered standard of practice to use chest radiography
as the initial investigation to diagnose pneumothorax [9, 10].
Unfortunately, several studies conrm that
radiography is extremely insensitive in detecting
pneumothorax regardless of the cause. In multiple systematic reviews, comparing chest radiography to other diagnostic modalities in over 1000
patients, chest X-ray has a sensitivity and specicity of 52% and 99%, respectively [11–13].
Point-of-care ultrasound has several signicant advantages for diagnosing pneumothorax.
Literature conrms that the sensitivity and specicity of lung POCUS is substantially better than
physical exam and especially chest X-ray [11,
12]. A 2020 Cochrane Review examining the
accuracy of lung POCUS vs supine chest radiography for the diagnosis of pneumothorax examined 1271 patients from 9 studies [14]. The
overall sensitivity and specicity of lung ultrasound was 91% (95% CI 85–94%) and 99%
(95% CI 97–100%), respectively. This is compared to the sensitivity and specicity of chest
radiography of 47% (95% CI 31–63%) and
100% (95% CI 97–100%) in the same studies.
POCUS can be performed within minutes of
patient contact, at the bedside and without any
risk to move the patient to the radiology department for further imaging. It is a test that can be
done rapidly in the span of less than 5min [15],
is easily reproducible in patients whose clinical
status changes, and lacks the risks of signicant
radiation exposure.
35 Point-of-Care Ultrasound fortheDiagnosis ofPneumothorax
427
General Principles ofLung POCUS
Almost all sonographic patterns of lung pathology, and especially for the assessment of pneumothorax, arise from the pleural line; a bright
echogenic line consisting of the apposition of the
parietal and visceral pleura [15–19].
For the diagnosis of pneumothorax, it is
important to use a probe with high frequency, in
order to maximize the resolution of structures
that lie close to the skin surface. The linear array
probe, generally with a frequency range of
5–12MHz is optimal. However, the curvilinear
and phased array probes can be used, albeit with
slightly decreased resolution. Furthermore, lung
POCUS focusses on the analysis and visualization of artefacts that are created when sound
waves interact with air, water, and lung tissue. It
is for this reason that lters on the ultrasound
machine be turned off or a dedicated lung preset
be used to enhance the visualization of these artefacts [15–17].
Technique
Because air within a Pneumothorax is nondependent, ultrasound assessment is done by
scanning the anterior chest wall of the supine
chest. With the use of a high-frequency linear
array probe, scanning is performed with the
probe in a longitudinal orientation with the probe
marker facing cephalad [18, 19] (Fig.35.1).
In order to diagnose a pneumothorax, it has
been traditionally taught to scan 2–3 successive
intercostal spaces along the midclavicular line on
either side [20, 21]. However, recently, it has
been shown through CT mapping that the majority of traumatic pneumothoraces are located in an
area between the parasternal border and the midclavicular line, and from the inferior aspect of the
clavicle to the physiologic lung points (liver lung
point on the right and cardiac lung point on the
left) [22]. As a result, the author suggests that
both lungs be scanned along two sagittal planes,
parasternal and midclavicular, from the angle of
Fig. 35.1 To diagnose
pneumothorax, a linear
array probe is placed
along the anterior chest,
in a longitudinal
orientation
428
Fig. 35.2 Areas to scan on both lungs to assess for pneumothorax (red boxes)
Louie to the liver lung point (on the right) and to
the cardiac lung point (on the left) (Fig.35.2). It
can be extrapolated that this technique will maximize the sensitivity and specicity of lung
POCUS for the diagnosis of pneumothorax.
Normal Findings andNomenclature
ofLung at thePleura
Once the probe is placed onto the patient’s chest
wall, identify the ribs with their corresponding
rib shadow (Fig.35.3). Approximately 0.5–1.0cm
deep to the ribs, you will nd the more echogenic
pleural line. This is the area of interest and where
you must focus your eyes.
During cycles of respiration, the normal vis-
ceral and parietal pleural will slide back and
forth, causing a lung sliding motion visualized
on your screen (Video 35.1). Some characterize
this shimmering effect similar to a column of ants
walking along the pleural line.
You may at times identify horizontal echo-
genic lines equidistant and in the far eld of the
pleural line. These “A-lines” represent a reverberation artifact from the pleura and provide no
J. Turner
meaningful information in the assessment for
pneumothorax.
Another artefact to identify (if present) are
B-lines and comet tails. These are vertical
hyperechogenic reverberation artefacts that originate from the pleural line, and move along the
pleural with respirations. These vertical lines
only originate from the visceral pleura and is
therefore, an indication of normal lung in contact
with parietal pleura.
Anatomically, the anterior right lung extends
from the angle of Louis of the sternum superiorly, to the pleura/liver interface inferiorly This
intersection between the lung and liver capsule is
called the liver lung point (Video 35.2). On the
left anterior lung, due to the cardiac image
extending into the lung, the intersection between
the pleura and the pericardium produces a car-
diac lung point (Video 35.3). Both of these liver
and cardiac lung points can mimic a pneumothorax and are important to identify [18].
Findings ofPTx
In 2012, Volpicelli etal. published international
evidence-based recommendations for point-ofcare lung ultrasound [21]. It is important to use a
stepwise approach to identify the structures or
artefacts that allow you to rule out or rule in a
pneumothorax (Fig.35.4).
1. Lung sliding: The rst nding to look for is
for the presence or absence of lung sliding.
Once the entire anterior lung is scanned, if
there is lung sliding throughout, you have
ruled out PTx in that lung. While the absence
of lung sliding strongly suggests the possibility
of a pneumothorax, there is an important differential of other pathologies that can result in
an absence of lung sliding (Table35.1).
2. B-lines/comet tails: Since these artefacts
only occur through the interaction of air and
water within lung tissue, and only originate
from the visceral pleura, the presence of either
conrms the apposition of the visceral pleura
against the parietal pleura, effectively ruling
35 Point-of-Care Ultrasound fortheDiagnosis ofPneumothorax
Fig. 35.3 Normal
appearing lung
Fig. 35.4 Stepwise
approach to assessing
for pneumothorax
Yes
a
Lung Sliding?
429
No
No Pneumothorax?
out pneumothorax in the area being scanned
(Video 35.4). However, it is important to note
that not all patients will exhibit comet tails or
B-lines. Therefore, their absence does not
suggest pneumothorax.
3. Lung Pulse: The lung pulse is caused by the
rhythmic transmission of cardiac activity
through an intact lung. Its presence therefore
also rules out pneumothorax. This is an important feature found in right main stem intuba-
B-lines (comet tails)?
Yes
b
Lung Pulse?
Yes
No
No
Lung Point?
No
c
Yes
Pneumothorax
tions, where a lung pulse will be present in the
left lung despite the lack of lung sliding due
to the absence of ventilation on that side
(Video 35.5).
4. Lung Point: A pneumothorax can be con-
rmed with the detection of a lung point. The
lung point refers to the specic location where
the visceral and parietal pleura separate from
each other to form the pneumothorax. On the
ultrasound image, a lung point will be
430
J. Turner
Table 35.1
Pneumothorax
Signicant atelectasis/consolidation
Main stem intubation
Acute respiratory distress syndrome (ARDS)
Severe brosis
Pleural adhesions
Apnea
Pulmonary contusion
Bullous disease
Differential diagnosis of absent lung sliding
identied as a specic area alternating
between a more echogenic lung sliding and an
area of absent lung sliding (or movement of
any kind) (Video 35.6). In emergency situations, it is suggested that the absence of both
lung sliding and B-lines provides enough
information for the safe diagnosis of pneumothorax, without the need to spend valuable
time identifying a lung point [21].
Videos 35.7, 35.8, and 35.9 provide typical
ndings of a pneumothorax, suggested by both
the lack of lung sliding as well as the lack of any
comet tail/B-line artefacts.
Pitfalls inthePOCUS Diagnosis
ofPneumothorax
There is clear evidence that the level of training
effects the reliability of POCUS to diagnose
pneumothorax, as non-expert physicians tend to
show lower accuracy for this tool [12, 14].
This indicates that the type of training is critical in ensuring proper technique (both through
didactic and bedside teaching). However, this
author believes this to be true of any diagnostic
modality taught in medical school, residency, or
post residency training. In cases of missed pneumothorax, it is not the ultrasound that is necessarily at fault, but the user’s ability to generate and
interpret images. For example, using the absence
of lung sliding as the sole criteria to conrm a
pneumothorax, without considering alternate
diagnoses or using additional criteria (B-lines,
lung pulse) is a clear cause of decreased accuracy. In addition, a common pit-fall is to look for
lung-sliding in only one or two chest locations,
rather than in multiple locations.
Case reports have reported missed pneumothorax based on atypical locations of located lung
collapse [23]. These case reports underline the
importance of careful and complete assessment
of each lung using both the step-wise approach as
well as the two sagittal scan approach outlined
above. Confusing the liver and cardiac lung
points as true lung points of a pneumothorax is
also reported and proper methodology to minimize this error is of critical importance [24].
It has been previously considered that the
location of the lung point can provide information with respect to the size of the pneumothorax.
However, up to now, lung POCUS is not recognized as an accurate method to differentiate
between small and large pneumothoraces [17].
Conclusion
Pneumothorax is a diagnosis that must be quickly
and accurately made to prevent morbidity and
mortality. Historical use of chest radiography has
been shown to be inadequate to rule out pneumothorax, and the use of CT is neither feasible nor
justied with the advent of POCUS.POCUS is a
rapid, reproducible bedside tool, that can rule in
and rule out pneumothorax as reliably as CT
without any of the inherent risks. However,
proper technique must be employed in order to
avoid the risk of false negatives as outlined above.
While not discarding other diagnostic modalities,
the use of lung POCUS should be considered as
the initial diagnostic tool for the diagnosis of
pneumothorax.
Summary Points
• Pneumothorax is a diagnosis that must be con-
sidered in any patient complaining of chest
pain and/or dyspnea. It is a diagnosis that must
be made quickly to avoid potential morbidity
and mortality.