Effectiveness and Safety of Real-Time Transthoracic Ultrasound-Guided Thoracentesis

Abstract

Purpose: The purpose of the present study was to specifically evaluate the effectiveness and safety of real-time ultrasound-guided thoracentesis in a case series of pleural effusion.

Patients and methods: An observational prospective study was conducted. From February 2018 to December 2019, a total of 361 consecutive real-time transthoracic ultrasound (TUS)-guided thoracentesis were performed in the Unit of Diagnostic and Interventional Ultrasound of the Research Hospital "Fondazione Casa Sollievo della Sofferenza" of San Giovanni Rotondo, Foggia, Italy. The primary indication for thoracentesis was therapeutic in all the cases (i.e., evacuation of persistent small/moderate pleural effusions to avoid super-infection; drainage of symptomatic moderate/massive effusions). For completeness, further diagnostic investigations (including chemical, microbiological, and cytological analysis) were conducted. All the procedures were performed by two internists with more than 30 years of experience in interventional ultrasound using a multifrequency convex probe (3-8 MHz). For pleural effusions with a depth of 2-3 cm measured at the level of the costo-phrenic sinus was employed a dedicated holed convex-array probe (5 MHz).

Results: In all the cases, the attempts at thoracentesis were successful, allowing the achievement of the therapeutic purpose of the procedure (i.e., the complete drying of the pleural space or the withdrawal of fluid till a "safe" quantity [a mean of 1.5 L, max 2 L] producing relief from symptoms) regardless of the initial extent of the pleural effusion. There were only 3 cases of pneumothorax, for a prevalence rate of complications in this population of 0.83%. No statistical difference was recorded in the rate of pneumothorax according to the initial amount of pleural fluid in the effusion (p = 0.12). All the pleural effusions classified as transudates showed an anechoic TUS appearance. Only the exudative effusions showed a complex nonseptated or a hyperechoic TUS appearance. However, an anechoic TUS pattern was not unequivocally associated with transudates. Some chronic transudates have been classified as exudates by Light's criteria, showing also a complex nonseptated TUS appearance. The cytological examination of the drained fluid allowed the detection of neoplastic cells in 15.89% cases. On the other hand, the microbiological examination of effusions yielded negative results in all the cases.

Conclusions: Real-time TUS-guided thoracentesis is a therapeutically effective and safe procedure, despite the diagnostic yield of the cytological or microbiological examinations on the collected liquid being very low. Future blinded randomized studies are required to definitely clarify the actual benefit of the real-time TUS-guided procedure over percussion-guided and other ultrasound-based procedures.

Keywords: effectiveness; pleural effusion; safety; transthoracic ultrasound; transthoracic ultrasound-guided thoracentesis.

Figure 1

(A) Dedicated convex-array probe (5 MHz) equipped with a holed guide for needle insertion during interventional procedures. (B) Ultrasound-guided thoracentesis performed by the employment of a dedicated holed convex-array with the patient in a sitting position.

Figure 2

(A) TUS scan showing an anechoic effusion with consensual parenchymal atelectasis during thoracentesis with a multifrequency convex probe (3.5 MHz). The tip of the needle is highlighted by a white arrow. (B) The corresponding CT scan shows a smooth thickening of the peribronchovascular interstitium and a bilateral pleural effusion with passive atelectasis of lower lobe in the right lung (black arrow).

Figure 3

A complex nonseptated pleural exudate in a patient with pneumonia, measured by two orthogonal views (longitudinal and transversal), viewed by longitudinal scan using a convex multifrequency probe (3.5 MHz).

Figure 4

(A) TUS scan showing a homogeneous iperechoic pleural exudates viewed by a convex multifrequency probe (3.5 MHz). The drained fluid was macroscopically hemorrhagic. (B) The corresponding CT scan shows a large right effusion in a patient with a diagnosis of metastatic kidney cancer.

Figure 5

(A) TUS scan showing a complex nonseptated effusion with consensual parenchymal atelectasis. The tip of the needle during TUS-guided thoracentesis with a multifrequency convex probe (3.5 MHz) is highlighted by a white arrow. (B) The corresponding CT scan shows an extensive apico-parieto-basal pleural effusion of greater right expression (black arrow) with consensual lower lobe atelectasis. A bilateral thickening of interlobular septa and some right ground-glass opacities with partial sparing of the lung periphery are also present (congestive heart failure).

Figure 6

Gain variation on the same TUS scan. (A) Anechoic pleural effusion with correct gain setting. (B) Falsely hyperechoic pleural effusion due to improper gain increase.

Figure 7

Stages of TUS-assisted thoracentesis. (A) Initial pleural effusion’s measurement using a convex 3.5 MHz holed probe. (B–D) Progressive lung re-expansion during drainage. The position of the needle tip (white arrows) is highlighted during all phases of the procedure until the needle is retracted.