It describes the ultrasonographic (echocardiographic) method of evaluating the pleura to detect abnormalities (effusion, pneumothorax, etc.), and to aid in doing some related procedures, such as aspirate & biopsy. It starts with describing the equipment needed, patients positioning, imaging technique & interpretation and finally addressing its limitations and comparing it to other modalities (e.g. chest x-rays, and CT scan).

1. BEDSIDE PLEURAL ULTRASONOGRAPHY:
EQUIPMENT & TECHNIQUE
Abd El-Salam AL-ETHAWI
Speciality Doctor (Fellow) in Paediatric Cardiology
Alder Hey Children’s Hospital, Liverpool – UK
2 0 2 2

2. OBJECTIVES:
To know:
 Equipment needed
 Patient’s positioning & preparation
 Imaging technique
 Major limitations & comparison to other
imaging modalities
4/6/2022
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL 2

3. INTRODUCTION
 Ultrasonography devices are used at the bedside to evaluate pleural
abnormalities and to guide thoracentesis and related procedures (such as
pleural drainage, catheter placement, and needle aspiration biopsy of
pleural or subpleural lung masses).
 The approach we will discuss is similar to that issued by the European
Respiratory Society (1)
1. Laursen CB, et al. Eur Respir J. 2021
4/6/2022
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL 4

4. EQUIPMENT USED?
 A wide variety of portable ultrasound machines with two-
dimensional scanning capability.
Transducers —
 A 3.5 MHz phased array probe (A) is ‘preferred’ for pleural
imaging.
 Designed for echocardiography; has a small footprint; a
multipurpose device (pleural, lung, and abdominal).
 It has sufficient depth of penetration to image structures
deep within the thorax, unlike the linear high frequency (B)
probe that has superior resolution but limited penetration.
 The curvilinear convex probe (C) may be used, if no phased
array probe is available.
A
B
C

5. EQUIPMENT USED?
 For detailed visualization of the pleural surface morphology, a
linear higher frequency 7.5 MHz probe (B) is required. It is
used specifically for imaging the pleural surface (irregularity,
lung point, and centromeric consolidations).
 Compared with the cardiac (phased-array) probe, this
vascular probe has:
o superior resolution but
o limited penetration (cannot be used to image deeper structures
within the thorax, e.g. the lung).
A
B
C
4/6/2022
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL 6

6. EQUIPMENT USED?
 Doppler is generally not required! – although
it is occasionally used to:
1. Differentiate a small pleural effusion from pleural
thickening (next fig.).
2. Since it can identify blood flow, some experts have
proposed that color Doppler may reduce the risk of
vascular injury from device insertion into the pleural
space
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

7. EQUIPMENT USED?
 Image storage — Many portable
ultrasonography machines have digital
image storage and transfer capability.
 Alternatively, the machine may be
equipped with a printer, thus allowing the
clinician to place a hard copy of the study
in the patient chart.
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

8. IMAGING TECHNIQUE
Patient position —
 The preferred position is the seated upright position
 resting their elbows on a secure surface that is
placed in front of them.
 In this position, the entire back is available for
scanning. The patient may also raise their arms to
permit access to image the lateral and anterior
portions of the chest.
 However, not all patients are capable of sitting upright
 supine or semi-supine positions are alternatives.

9. IMAGING TECHNIQUE
Patient position —
 Unstable, unable to sit upright, severe
cardiopulmonary failure, or bedridden 
scanned in the supine or semi-supine
position with the ipsilateral arm adducted
across the chest towards the opposite side.
 See four patient positions for sonographic
detection of pleural effusion and
subsequent thoracentesis.

10. IMAGING TECHNIQUE
 If the effusion is large, it may be identified in
the mid-axillary line (B).
 If the effusion is small  moving the probe to a
more posterior position (D), so that it is pressed
into the mattress and angled upwards to
visualize the effusion.
 Alternatively, the patient may be placed in a full
lateral decubitus position (C).
N.B. Positioning the critically-ill patient for thoracentesis is often
challenging and requires several team members to be involved. If the
patient is on mechanical ventilatory support, one team member is
assigned responsibility for maintaining position of the endotracheal
tube throughout the procedure.

11. IMAGING TECHNIQUE
Machine setup —
 The ultrasonography machine is positioned so the
screen is easily visible from the operator's working
position
 Ambient lighting is reduced to maximize screen
contrast
 Adjusting depth and gain settings on the machine
for optimal visualization. Many portable machines
have abdominal "preset" settings that work well for
thoracic scanning. Some machines have lung
"preset" settings- depends on operator preference
& machine!

12. IMAGING TECHNIQUE
 Depth – adjusted, target of interest in the centre:
o shallow for near field structure (e.g. pleural surface)
o deep for full extent of a pleural effusion
 Gain setting – to optimize visualization of anatomic
boundaries.
 Probe – perpendicular to the skin surface, in between
ribs space, probe marker directed in ‘cranial’ direction.
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

13. IMAGING TECHNIQUE
 Scanning plane – adjusted to center the interspace on
the screen with the ribs on either side
 Probe marker standardizes image acquisition  yields
a longitudinal axis view of the interspace with the
cranial direction projected to the left of the screen.
Structures near the skin surface project to the top of
the screen while deeper structures project towards the
bottom
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

14. IMAGING TECHNIQUE
Scanning technique —
 Because sound waves do not pass through air, acoustic
gel is liberally applied to skin to provide an airless
interface; gel also permits the probe to slide easily.
 The probe is systematically moved craniocaudally from
one interspace to another and from right to left so
multiple interspaces may be examined in a short time.
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

15. IMAGING TECHNIQUE
Scanning technique —
This process allows the examiner to:
 Locate relevant anatomic landmarks (eg, diaphragm, lung,
heart)
 Identify and characterize any abnormalities (including
pleural fluid), if present
 Identify a safe site for needle insertion (if thoracentesis or
biopsy is planned)
N.B. If thoracentesis is performed separately from the initial diagnostic ultrasonography, the
examination is always performed immediately before performance of the thoracentesis; as
there may have been interim change in the size and distribution of effusion between the two
scans.
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

16. IMAGING TECHNIQUE
The anatomic boundaries —
 The diaphragm, chest wall, and lung are identified. The
pericardium may also be a border, so it is prudent to
identify the heart when planning thoracentesis on the
left side
 Adjacent clip - 2D transthoracic echocardiogram (TTE)
from the parasternal long axis window showing both
pericardial (◊) and pleural effusions (asterisk).
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

17. IMAGING TECHNIQUE
Diaphragm — Must be ‘positively’ identified;
 an echogenic curvilinear structure (A) above the liver
or spleen
 downward (caudad) movement of the diaphragm with
inspiration
 best confirmed by first identifying the hepatorenal (B)
and splenorenal (C) recesses (another curvilinear
structures that may be confused with the diaphragm)
 Position – variable and may be low in the seated
patient with a large effusion or high in the supine
patient or when there is coexisting abdominal obesity,
ascites, or diaphragmatic paralysis.
A
B
C
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

18. IMAGING TECHNIQUE
Chest wall — Identification of the structures allows
accurate measurement of the depth of needle
penetration - if required.
The ultrasonography anatomy of the chest wall is as
follows
 Epidermis – When using the 7.5 MHz linear probe,
this is visible as an echogenic line in the near-field;
few millimeters in thickness.
BE CAREFUL! It is not visible as a distinct anatomic
entity when using the 3.5 MHz phased-array echo
probe.
The 7.5 MHz linear probe is used obtain a detailed view of the
anatomy of the chest wall.
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

19. IMAGING TECHNIQUE
 Dermis – a hypoechoic area located deep to the
epidermis.
 Intercostal muscles – a hypoechoic area deep to
the dermal compartment; contract with respiration
– prominent with respiratory distress.
 Ribs – hyperechoic curvilinear structures adjacent
to the intercostal muscle. The periosteum causes
‘posterior acoustic shadow’ i.e. blocks visualization
of structures deep to the rib.
Over the medial anterior chest, rib shadowing is less
prominent – WHY?
The 7.5 MHz linear probe is used obtain a detailed view of the
anatomy of the chest wall.
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

20. IMAGING TECHNIQUE
 The pleural line – a white line approximately 0.5
cm deep to the periosteal reflection.
 When a pleural effusion is present  the visceral
and parietal surfaces are separated by the pleural
effusion.
The 7.5 MHz linear probe is used obtain a detailed view of the
anatomy of the chest wall.
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

21. IMAGING TECHNIQUE
LUNG SLIDING VS PULSE?
 Lung sliding – respirophasic
movement of the visceral against the
parietal pleural surfaces; seen as a
shimmering mobile pleural line that
moves in synchrony with the
respiratory cycle N
 Does it exclude pneumothorax?
Lung sliding: respirophasic shimmering to and fro movement of the visceral and parietal surfaces
4/6/2022
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL 22

22. IMAGING TECHNIQUE
LUNG SLIDING VS PULSE?
 Lung pulse – pleural line moves
in a cardiophasic fashion due to
transmission of the cardiac
pulsations N
Lung pulse: cardiophasic movement of the visceral parietal pleural surface (arrow)
4/6/2022
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL 23

23. IMAGING TECHNIQUE
 Lung — Constitutes the third typical boundary that is
sought by the operator in identifying the presence of
pleural fluid.
 Normally aerated lung is not visible as a distinct
structure. WHY? (A lines pattern, Reverberation
artefact)N
Effusion with consolidation/atelectasis!
 Lung appears as a tissue density structure demarcated
by the effusion with alveolar consolidation due to
compressive atelectasis  ‘hepatization of lung’
 Degree of atelectasis depends on the size of the
effusion: large effusions  lobar or even total lung
compressive atelectasis.

24. IMAGING TECHNIQUE
HOW TO RECOGNIZE EFFUSION?
 The hypoechoic space — PE appears as
hypoechoic space that is surrounded by the
anatomic borders described above.
 PE may be characterized according to its pattern
of echogenicity into the following 4 types:
1. Anechoic when it is echo-free (ie, black)
Lung is a small consolidated structure (arrow) within large
anechoic PE (arrowhead) (compressive atelectasis).
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

25. IMAGING TECHNIQUE
 The hypoechoic space — TYPES OF PE:
2. Homogenously echogenic: when it is
hypoechoic (ie, not anechoic) and no discrete
echogenic elements observed within the
effusion
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

26. IMAGING TECHNIQUE
 The hypoechoic space — TYPES OF PE:
3. Complex non-septated: when discrete echogenic elements are observed within the
effusion
Complex non-septated Homogenously echogenic

27. IMAGING TECHNIQUE
 The hypoechoic space — TYPES OF PE:
4. Complex Septated: when strands or septa are
observed
 Clinical Significance?
o Anechoic effusion  usually a transudate while the
presence of echogenicity within the pleural effusion
usually indicates an exudate.
o Septations or internal echogenicity are generally
exudates
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

28. IMAGING TECHNIQUE
 Clinical Significance?
o Pleural thickening >3 mm, nodularity, or
coexisting lung abnormality (consolidation,
abscess)  exudative PE
o A ‘swirling’ pattern, (floating mobile echogenic
particles)  exudative PE
A swirling pattern (arrow) – floating mobile echogenic particles within the effusion
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL

29. IMAGING TECHNIQUE
 Dynamic findings — A variety of dynamic findings are associated with a
pleural effusion. These include: movement of the diaphragm and heart as
well as respirophasic and cardiophasic movement of the atelectatic lung,
strands, septations, and echogenic material within the effusion.
4/6/2022
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL 30

30. ULTRASONOGRAPHY VS OTHER IMAGINGS!
 A retrospective analysis of 66 patients suggested that ultrasonography was
more sensitive than chest radiography (69 versus 61 percent) but less
sensitive than computed tomography (69 versus 76 percent) for the
diagnosis of a complicated parapneumonic effusion
Svigals PZ, et al. Thorax. 2017
4/6/2022
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL 31

31. ANY LIMITATIONS?
Limitations —
1. Patient-specific factors such as obesity, massive edema, heavy musculature,
chest wall dressings, and inability to position the critically-ill patient may
degrade image quality.
2. Complex long-standing empyema may make it difficult to identify the
characteristic features of PE.
THUS, if USS is not adequate for imaging, chest CT Scan is indicated.
4/6/2022
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL 32

32. SUMMARY
 Given the cost savings, time efficiency, convenience, accuracy, and clinical applications, USS
is often chosen by physicians as the preferred imaging modality for rapid bedside imaging
of the pleura
 A two dimensional USS machine with a 3.5 MHz phased-array transducer is typically used
 The three defining characteristic USS findings of a pleural effusion include identification of
the typical anatomic boundaries (diaphragm, chest wall, and lung) that surround a relatively
hypoechoic space in which there are associated dynamic findings (eg, respirophasic or
cardiophasic movement of lung, effusion, and diaphragm).
4/6/2022
AL-ETHAWI | ALDER HEY CHILDREN'S HOSPITAL 33

33. THANKS FOR LISTENING!
Any Question?
Reference: Paul Mayo. Bedside pleural ultrasonography: Equipment,
technique, and the identification of pleural effusion and pneumothorax. Up
to Date. April 2021