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Correspondence |

Is Pleural Ultrasonography Better Than Chest Radiograph for Follow-up Resolution of Pneumothorax? FREE TO VIEW

Saadah Alrajab, MD, MPH
Author and Funding Information

From the Department of Pulmonary and Critical Care, Louisiana State University-Shreveport.

Correspondence to: Saadah Alrajab, MD, MPH, Department of Pulmonary and Critical Care, Louisiana State University-Shreveport, 1512 W Kirby Pl, Shreveport, LA 71103-3822; e-mail: salraj@lsuhsc.edu


Financial/nonfinancial disclosures: The author has reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/site/misc/reprints.xhtml).


© 2011 American College of Chest Physicians


Chest. 2011;139(3):727-728. doi:10.1378/chest.10-2688
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To the Editor:

In a recent issue of CHEST (September 2010), Galbois and colleagues1 concluded that pleural ultrasonography (PU) was more accurate and gave faster results than chest radiograph (CXR) in follow-up of pneumothorax resolution. Although we (in the Department of Pulmonary and Critical Care at Louisiana State University) believe that PU is a great diagnostic tool in the ICU, we disagree with some of the findings of their research and have concerns related to its validity.

The study used a single center and single investigator in an operator-dependent technique. CXRs were read by the caring physician rather than by an independent experienced radiologist; this may have led to a bias favoring PU over CXR. The confirmation of pneumothorax was done in most cases by a nonstandard method (aspiration of 10 mL of air) and may have picked up cases of no clinical significance.

Although we understand that the study was designed to evaluate the resolution of pneumothoraces, it can still be criticized for using the same subjects (44 patients), obtaining at least three CXRs and three PUs on each, and counting these tests as independent variables. Furthermore, the use of Fisher exact test for data analysis without establishing independency in this situation is not supported.2

The study population was mainly patients with primary spontaneous pneumothoraces (31/44), except for only one subject with dysmorphic emphysema in which PU gave false-positive results. The prevalence of severe emphysema in the patient population with pneumothoraces in practice is high, causing concerns about the ability to generalize the findings of this study to the external population.

The sample size of this study was too small, especially when the independency issue stated previously is considered. According to our calculations, for a well-powered study, approximately 320 independent subjects and tests are needed. Finally, the clinical significance of detecting a small loculated pneumothorax by PU cannot be determined in this study, and overtreatment with possible negative outcomes could be an issue if we apply the results of this study to practice.

Galbois A, Ait-Oufella H, Baudel JL, et al. Pleural ultrasound compared with chest radiographic detection of pneumothorax resolution after drainage. Chest. 2010;1383:648-655. [CrossRef] [PubMed]
 
Sabin C, Petrie A. Medical Statistics at a Glance. 2006;2nd ed Malden, MA Blackwell Publishing:61-64
 

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References

Galbois A, Ait-Oufella H, Baudel JL, et al. Pleural ultrasound compared with chest radiographic detection of pneumothorax resolution after drainage. Chest. 2010;1383:648-655. [CrossRef] [PubMed]
 
Sabin C, Petrie A. Medical Statistics at a Glance. 2006;2nd ed Malden, MA Blackwell Publishing:61-64
 
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