Chest
Volume 146, Issue 5, November 2014, Pages 1286-1293
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Original Research Pulmonary Procedures
Novel Use of Pleural Ultrasound Can Identify Malignant Entrapped Lung Prior to Effusion Drainage

https://doi.org/10.1378/chest.13-2876Get rights and content

BACKGROUND

The presence of entrapped lung changes the appropriate management of malignant pleural effusion from pleurodesis to insertion of an indwelling pleural catheter. No methods currently exist to identify entrapped lung prior to effusion drainage. Our objectives were to develop a method to identify entrapped lung using tissue movement and deformation (strain) analysis with ultrasonography and compare it to the existing technique of pleural elastance (PEL).

METHODS

Prior to drainage, 81 patients with suspected malignant pleural effusion underwent thoracic ultrasound using an echocardiogram machine. Images of the atelectatic lower lobe were acquired during breath hold, allowing motion and strain related to the cardiac impulse to be analyzed using motion mode (M mode) and speckle-tracking imaging, respectively. PEL was measured during effusion drainage. The gold-standard diagnosis of entrapped lung was the consensus opinion of two interventional pulmonologists according to postdrainage imaging. Participants were randomly divided into development and validation sets.

RESULTS

Both total movement and strain were significantly reduced in entrapped lung. Using data from the development set, the area under the receiver-operating curves for the diagnosis of entrapped lung was 0.86 (speckle tracking), 0.79 (M mode), and 0.69 (PEL). Using respective cutoffs of 6%, 1 mm, and 19 cm H2O on the validation set, the sensitivity/specificity was 71%/85% (speckle tracking), 50%/85% (M mode), and 40%/100% (PEL).

CONCLUSIONS

This novel ultrasound technique can identify entrapped lung prior to effusion drainage, which could allow appropriate choice of definitive management (pleurodesis vs indwelling catheter), reducing the number of interventions required to treat malignant pleural effusion.

Section snippets

Study Design

This was a prospective multicenter cohort study, conducted between March 2012 and October 2013. The study was approved by the Human Research Ethics Committee at Royal Brisbane and Women's Hospital (Queensland, Australia) (approval number: HREC/11/QRBW/452).

Consenting patients undergoing drainage of at least 500 mL for suspected malignant pleural effusion were recruited. The primary outcome was the ability of predrainage M mode and STI to identify entrapped lung as defined by postdrainage

Results

Eighty-three consecutive patients were recruited for the study; two were excluded as they were designated as not scorable on postdrainage radiology (Fig 2). Fifty-one were men, and the mean age was 66 years (62-70 years) (95% CI). The final diagnosis was pleural malignancy (59%), parapneumonic (8%), heart failure (4%), and other (29%). Mean pleural drainage volume was 1,351 mL (1,194-1,509 mL) (95% CI).

There were 34 patients in the development set and 47 in the validation set. The number of

Discussion

This study documents a novel approach to the identification of malignant entrapped lung, using preprocedure ultrasonography. M mode and STI strain analysis of the atelectatic lung gave very favorable results for diagnostic parameters, and measurements demonstrated a high level of reliability. Although some features can suggest the presence of entrapped lung (thickening of the visceral pleura at ultrasound, elevated PEL, or basilar pneumothorax on postdrainage imaging), it is often very

Acknowledgments

Author contributions:M. R. S. takes responsibility for the accuracy of data and manuscript content. M. R. S. contributed to study design and patient recruitment, assisted with ultrasound scans, analyzed data, and wrote the manuscript; A. K. C. L. contributed by performing ultrasound scans; A. C. T. N. contributed to the analysis of the ultrasound images; F. B. contributed to postdrainage radiology scoring; W. Y. S. W. contributed to the analysis of ultrasound images for reliability testing; D.

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Funding/Support:Dr Salamonsen was supported by research scholarships from the National Health and Medical Research Council and the RBWH Foundation.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

originally published Online First July 10, 2014.

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