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440 oracic ultrasound
Figure 8 – A: Veres needle with tubes, bag, three way stopcock and syringe. B: Veres needle
(particular). C: The sharp tip of the Veres needle protected by the protruding inner blunt cannula.
For drainage procedures (thoracentesis, pericardiocentesis, aspiration of cysts, abscesses,
pseudocysts, etc.) it can sometimes be more useful to place a catheter into the cavity, and
then eventually leave it in place for follow-up actions. For this purpose various commercial
kits with different characteristics are used (Fig. 9).
Figure 9 – A kit for Pigtail catheter insertion (Seldinger method), containing needles,catheter, guidewire
and dilators.
We frequently employ catheters for central venous cannulation inserted with the Seldinger
technique (Fig. 10). In the pleural cavity, the soft catheter avoids the possibility of PNX which
can sometimes occur following a traumatic puncture.
Figure 10 – Catheter with guidewire inside.
Interventional chest ultrasound 441
With the Seldinger method, the needle (different calibers) that has been introduced into the
target is used to insert a metal guide (guidewire) (Fig.11). e guidewire may be variously
configured, uniformly flexible or with a flexible tip. Its length and thickness are generally
measured in inches (0.016 to 0.038 inch, corresponding to 0.46 and 0.97 mm).
Figure 11 – Needle with guidewire inside.
Subsequently, after removing the needle, the catheter is slid on the metal guide aided by a
small skin incision and the use of dilators. Finally, the guide is removed.
is technique is used for vascular applications (Fig. 12), but may also be used to drain abscesses and the pleural or pericardial cavities. It is simple, but has the drawback of introducing
a small amount of air into the pleural cavity.
Figure 12 – A complete set for venous cannulation by Seldinger method.
In this case, the air may be appropriately aspirated, assessing on echography the disappear-
ance of lung points. (Fig. 13).
Another technique exploits an “introducer”. A special sheath of polyethylene is inserted with
the Seldinger method or by means of a large needle (one shot). e catheter is then passed
on the guide of the sheath (the introducer) inside the cavity or the vessel lumen. Finally, the
sheath is longitudinally open in two parts and removed (peel away system). It is basically a
vascular technique.
Using the “trocar” method, the catheter is mounted on a rigid and sharp metal stand, that
allows its penetration through tissues. Once the catheter is in place, the trocar is removed.
is method requires caution during the penetration, as the trocar may damage deep structures (Fig. 14).
442 oracic ultrasound
Insertion of the guide wire into the vein
Vein
Guide wire into the vein
Vein
Catheter
Vein
Catheter in place
Vein
Figure 13 – Sequence of steps for the introduction of a catheter according to the technique of the guide
wire (Seldinger).
Figure 14 – A: 16 F soft thoracostomy catheter with its stylet (trocar). B: the mounted device ready
for the use.
Kits that employ pigtail catheters of various sizes are very practical for pleural drainage. ey
are mounted inside or outside a trocar, or a large needle (intracath and extracath). Once the
instruments reach the cavity, the trocar (or needle) is removed and the catheter is slid into the
collection. Pigtail catheters can also be positioned with the Seldinger technique over a guidewire.
Catheters can be simple, with distal inflatable balloon, Malecot-type (with basket tip) or
with terminal foldings suitable to fix them (pigtail, J-shape). e catheter may contain one
or more lumes and holes, to allow continuous washing (Fig. 15).
e materials used in the production of catheters are various, and this feature affects their
flexibility, strength, and the possibility of kinking and fouling.
Silicone is very flexible and resistant to fouling, more than teflon and much more than latex.
Polyethylene or polyurethane catheters are also suitable.
e caliber of the catheters is generally measured in French (Fr), with wide availability of
sizes, ranging from 5 to over 24 Fr (1.7-8 mm).
Interventional chest ultrasound 443
Figure 15 – Catheters for pleural drainage. Left above: 12 F J type trocar catheter. Left below: 10 F
Pigtail catheter (Seldinger). Right: straight 16 F thoracostomic tube (trocar system), without the stylet.
A list of the basic material for thoracic interventional ultrasound is summarized in Table 3.
Table 3 – List of materials needed for interventional ultrasound
• Sterile gloves and gowns • Wire for sutures (silk 0, 1/0)
• Skin antiseptic solution (povidone iodine) • Tools for sterile blunt dissection (curved clamp)
• Sterile drapes • Set of catheters with guidewire (Seldinger,
pigtails 10-14 F) and dilators
• Sterile gauze • Set of catheters mounted on the trocar
• Syringes and (spinal) needles 25-18 G • Catheter for pericardiocentesis (Seldinger)
• 14-18 G needle cannula • Standard chest tubes
• Veress needles with three-way set and
collection bag
• Local anesthetic (lidocaine 1%) • Central venous catheters
• Scalpel n. 10
• Systems for closed drainage and connection
pipes
➣ Local anesthesia
In almost all interventional procedures, except those in which thin needles (> 21 G) are used
for a short time (seconds), it is preferable to practice a good local anesthesia. A careful anesthetic infiltration ensures the tranquility of the patient and allows the execution of all operations with the necessary calm. In our practice we prefer ultrasound-guided local anesthesia.
e visualization of the target (a vessel, the pleural or pericardial cavity) allows to estimate
the thickness of the overlying soft tissue, its vascularization, and the most suitable way for
the passage of the needle. After this assessment it is easy to introduce obliquely, under continuous view, a 25 G spinal needle connected to a syringe with 5-10 ml of 1% lidocaine.
e anesthetic is injected along the way of the needle. An accurate anesthetic block of the
derma (in some cases, a scalpel incision may be necessary), the costal periosteum and the
444 oracic ultrasound
subserosal connective is very important. For a full effect, the anesthetic is injected in the
parietal subpleural connective tissue, to create a wheal under the parietal pleura. Operating
in continuous view without injecting air bubbles, the planes above the target are dissociated
from the anesthetic liquid.
In addition to the anesthetizing action, this procedure allows to test with a thin needle the
way that will be covered subsequently by the device introduced.
If these actions are performed optimally, each additional maneuver will be absolutely painless.
➣ Coupling of the device with the probe
is is a particularly important topic, since it affects the production of good ultrasound images and therefore the probability of hitting the target by the needle. A priori it is not possible
to favor one or the other system, as both have strengths and weaknesses. It is desirable that
the operator acquires equal confidence with the two systems, so as to use one or the other
depending on the personal preference or specific needs.
Figure 16 – Cannulation of the right internal jugular vein with coplanar technique (in plane) (from:
Auyong DB, Hsiung RL. Ultrasound in central venous cannulation. Adv Anesth 2010; 28: 59-79).
According to the ultrasound-guided coplanar approach (in plane approach) the needle (or
another device) is directed toward the target remaining on the same scan plane of the probe.
In the case of cannulation of a vessel, the probe is placed longitudinally to the vessel and the
needle is obliquely introduced underneath the short side of the probe, so as to be intercepted
by the ultrasound beam. e advantage of this technique is that the needle is seen in real time
along its path and in its entirety, until it reaches the target (Figs. 16-17). Its biggest drawback
is the difficulty in maintaining all the needle and the target in the ultrasound scanning plane9.
In the transverse approach (out of plane), the probe is placed transversely on the target and
the needle is introduced perpendicularly underneath the central point of the long side of the
probe (Figs. 18-19).
e advantage of this approach is that the needle necessarily appears on the scan plane as an
echogenic point. However, only with coordinated oscillating movements of the probe, it is
Interventional chest ultrasound 445
possible to establish if either the tip or rather the section of the axis of the needle is visualized.
Small “percussion” movements of the needle greatly facilitate its visualization.
Figure 17 – The in plane technique allows the whole visualization of the needle, which appears as a
hyperechoic linear structure.
Figure 18 – Cannulation of the right internal jugular vein with out-of-plane technique (from: Auyong
DB, Hsiung RL. Ultrasound in central venous cannulation. Adv Anesth 2010; 28: 59-79).
e most effective technique should firstly provide for the display of the needle tip under the
probe, then a coordinated “fan-like” movement of the probe is necessary, so as to maintain
constant the vision of the needle tip getting toward its target10.
e operator can choose one of these two approaches, but the “in plane” access requires that
the probe is aligned with the target (a typical example, an intercostal space) and this may fail
in narrow body regions, that are completely occupied by the probe11.
446 oracic ultrasound
Figure 19 – With the out-of-plane technique, the needle tip appears as a hyperechoic punctiform
structure.
➣ Thoracentesis
oracentesis is the simple puncture of the pleural cavity through the chest wall, to drain the
pleural fluid12. Analysis of the pleural fluid drained allows the distinction between exudate
and transudate (Tab. 4).
Table 4 – Common causes of essudate or transudate effusion and criteria for their differentiation
Type of effusion Transudate Exudate
Common etiologies Heart Failure
Cirrhosis
Nephrotic syndrome
Pulmonary embolism
Differential diagnosis
Ratio between proteins in
pleural fluid and serum
Ratio of LDH in pleural
fluid and serum
LDH in pleural fluid < 2/3 of normal maximum
Modified from: Light RW. Pleural effusion. N Engl J Med 2002; 346: 1971-1977.
< 0.5 > 0.6
< 0.6 > 0.5
limit in serum
Neoplasms
Pneumonia
Trauma
Tuberculosis
Pulmonary embolism
Rheumatoid arthritis
Systemic Lupus Erythematosus
> 2/3 of normal maximum limit in
serum
Interventional chest ultrasound 447
Other parameters of the pleural fluid may indicate specific etiologies (Tab. 5).
Table 5 – Possible etiologies of effusion on the basis of parameters deductible from chemical and
culture examination
Parameter Meaning
Differential and numerical cell count The polymorphonuclear leukocytes indicate an
acute process (pneumonia or pulmonary embolism).
Mononuclear cells suggest a chronic disease (cancer
or tuberculosis)
Gram stain and culture Identification of germs
Hematocrit A hematocrit of the pleural fluid between 1% and
20% indicates neoplasm, pulmonary embolism or
trauma. A value > 50% indicates hemothorax
Glucose Glucose values < 60 mg/dl in the pleural fluid suggest
pneumonia or cancer. There is also the possibility
of tuberculosis, rheumatoid arthritis, systemic lupus
erythematosus or Boerhaave syndrome
Cytological profile Search for specific etiologies
pH A pH < 7.2 suggests a drainage with tube or catheter
Triglycerides A level in the pleural fluid > 110 mg/dl is suggestive of
chylothorax
Amylase A high level of amylase in the pleural fluid is
suggestive of pancreatitis or oesophageal rupture
Any long-term pleural effusion tends to show a predominance of lymphocytes. A recent effusion containing lymphocytes narrows the diagnostic hypotheses to the conditions indicated
in Table 6.
Table 6 – Diagnostic hypotheses in the case of pleural effusion with lymphocytic predominance
(> 50% mononuclear cells)
• Malignant neoplasms (including metastatic adenocarcinoma and mesothelioma)
• Tubercolosis
• Lymphoma
• Heart failure
• Effusion after surgery (CABG)
• Rheumatoid effusion
• Chylothorax
• Uremic pleurisy
• Sarcoidosis
• Yellow nail syndrome
448 oracic ultrasound
Table 7 – Complications of thoracentesis
Complication Notes
PNX More frequent without ultrasound support. Rare with ultrasound
support. It rarely requires drainage with tube. It can occur without
direct trauma to the lung in cases of malignant effusion and/or
pleural repetitions, when the lung is compressed and hardened
into the liquid (Heidecker J et al. Pathophysiology of pneumothorax
following ultrasound-guided thoracentesis. Chest 2006; 130: 1173-
1184). Some evidence states that the drainage of fluid greater
than 1.2 l predisposes to the development of PNX (Josephson T et
al. Amount drained at ultrasound-guidedthoracentesis and risk of
pneumothorax. Acta Radiol 2009; 50: 42-47)
Pain Absent with a good local anesthesia
Cough Frequent, it may cause displacement of the needle, altering the
relationships of the chest wall with lung and parenchymal lesions
Hemothorax It requires care to avoid injury to the intercostal arteries and internal
mammary arteries. The posterior intercostal arteries occupy a more
central position in the intercostal space
Injury of intra-abdominal
organs
Re-expansion pulmonary
edema
There is no risk if ultrasound is used, many puncture sites carried
out without ultrasound guide are under the diaphragm
This edema is realized in the case of drainage of pleural fluid or
air (PNX). It is rare (0-1%). It can be prevented draining no more
than 1.5 liters of fluid, stopping the evacuation in the event of
symptoms and paying attention to young people and people with
lung compression (> 7 days) (Echevarria C et al. Does re-expansion
pulmonary oedema exist? Interact Cardiovasc Thorac Surg 2008; 7:
485-490)
Despite being considered a procedure with low invasiveness, thoracentesis, if performed with
blind technique, involves a risk of pneumothorax estimated at around 20-39% of cases. Other
possible complications are listed in Table 713.
Even in the absence of randomized studies comparing the ultrasound-guided procedure
with the blind thoracentesis, several reports have associated the use of ultrasound with fewer
complications.
Raptopoulos and co-workers report a reduction in the incidence of pneumothorax from
18% to 3%, and with ultrasound-guided procedures the need of the drain tube for iatrogenic
pneumothorax is lower
14-15
.
e risk reduction for PNX appears only with real-time procedures, in which the needle is
inserted under ultrasound control, but not with the techniques defined “X marks the spot”
in which the thoracic puncture is made in a point previously identified with ultrasound, and
physically marked on the chest.
Another advantage of echoguided thoracentesis concerns subjects for whom the blind puncture is not effective.
Interventional chest ultrasound 449
Some studies suggest that pleural fluid is obtained in over 88% of echoguided thoracentesis
performed after ineffective punctures. It is important to note that, after ineffective approaches,
the ultrasound scan shows a too low position (below the diaphragm) of the puncture site16.
➣ Chest drains
Chest drains are made by placing a tube of variable diameter in the thoracic cavity with the
purpose of evacuating pleural collections. ey have many applications and are necessary
when fluid (transudate, exudate, blood, chyle, pus) or air in the pleural cavity reach volumes
that alter the respiratory dynamics.
Even simple transudates, if not responsive to medical therapy, may require drainage. Small fluid
collections, which do not affect ventilation, can be punctured for diagnostic purposes only.
Indications for drainage are pneumothorax, empyema, hemothorax, complicated parapneumonic effusions and effusions that cause respiratory failure. Table 8 summarizes the indications for a chest drain.
Table 8 – Indications for placement of a chest drain
PNX
•inanyventilatedsubject
•hypertensivepneumothoraxafterinitialevacuationwithneedle
•persistentorrecurrentpneumothoraxaftersimpleaspiration
•secondaryspontaneouspneumothoraxinpatientsmorethan50year-old
Malignant effusions associated or not with pleurodesis
Empyema and complicated parapneumonic effusions
Traumatic hemopneumothorax
Effusions after surgery (thoracotomy, esophagectomy, cardiac surgery)
Bronchopleural fistula
Small pneumothorax are reabsorbed spontaneously with daily speed estimated to be about
1.25% of the hemithorax volume. Many small primary spontaneous pneumothorax therefore
can be treated conservatively. In these cases aspiration of air may be motivated to speed up
healing or in case of symptoms.
e application of a catheter or thoracostomy tube is practiced after gaining informed consent, having assessed drug history (use of anticoagulants and antiplatelet agents) and after a
coagulation function assessment. rombocytopenia (< 50,000 elements/mmc) and elongation
of INR (> 1.5) require attention, although they do not represent absolute contraindications
for life-saving procedures.
ese criteria apply to any interventional procedure, especially when performed on deep tissues
and/or in areas where compression is not very effective. e intake of aspirin and Clopidogrel,
given its long action on platelets, should be suspended at least 7-10 days prior to surgery.
Very recently however, it has been shown that the risk of bleeding after ultrasound-guided
thoracentesis is low even in the presence of abnormalities in INR and platelet count17.
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