Strengths and Limitations of a Small Randomized Trial Comparing Manual and Vacuum Drainage in Thoracentesis : Journal of Bronchology & Interventional Pulmonology

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Online Articles: Letters to the Editor

Strengths and Limitations of a Small Randomized Trial Comparing Manual and Vacuum Drainage in Thoracentesis

Senitko, Michal MD*,†; Murphy, Terrence E. PhD; Puchalski, Jonathan T. MD, MEd

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Journal of Bronchology & Interventional Pulmonology 26(3):p e43, July 2019. | DOI: 10.1097/LBR.0000000000000583
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In Reply:

We thank Sagar and colleagues for their Letters to the Editor and appreciate this opportunity to highlight the contributions and limitations of our research examining the use of vacutainers when performing thoracentesis.

We acknowledge that our pilot study1 is small and therefore prone to greater variability than the larger studies cited by Sagar et al.2,3 We further acknowledge that our overall rate of pneumothorax of 3.0% (3 events among 100 procedures) is greater than the 0.6% reported by Sagar and colleagues (4 events among 709 procedures). Nonetheless, we assert that our rate of pneumothorax is not inflated with respect to those reported by other large sample studies. For example, Jones et al4 report a rate of pneumothorax of 2.6% (24 events among 941 procedures) and Patel et al5 report a rate of 2.8% (246 events among 8824 procedures). In addition, a meta-analysis of 24 studies that included 6605 thoracenteses demonstrated an overall pneumothorax rate of 6.0%.6

Given that this pilot study is intended to motivate larger, more comprehensive studies comparing the safety of manual and vacuum drainage, we are impressed with the consistency of our findings. If, for the sake of argument, we attribute the rate of pneumothorax in our study to a simple matter of sample size, it seems unlikely that the same participants randomized to the manual drainage arm would simultaneously exhibit a markedly lower rate of early termination as well as a significantly lower level of pain.

In summary, although we agree that our small sample size is a factor when examining “rare events” such as pneumothorax or hemothorax, it is very unlikely that it would uniformly bias the results from this carefully conducted RCT in favor of manual drainage. For this reason we stand by the last sentence in our abstract: “Although larger studies are needed, this pilot study suggests that manual aspiration provides greater safety and patient comfort.”

Michal Senitko, MD*†

Terrence E. Murphy, PhD‡

Jonathan T. Puchalski, MD, MEd†
*Division of Pulmonary, Critical Care and Sleep Medicine, University of Mississippi Medical Center School of Medicine Jackson, MS
†Division of Pulmonary Critical Care and Sleep Medicine Yale University School of Medicine
‡Claude D. Pepper Older Americans Independence Center at Yale, Program on Aging, Yale School of Medicine New Haven, CT


1. Senitko M, Ray AS, Murphy TE, et al. Safety and tolerability of vacuum versus manual drainage during thoracentesis: a randomized trial. J Bronchology Interv Pulmonol. 2019;26:166–171.
2. Sagar SA, Bashoura L, Nasim F, et al. Assessing the safety of rare events; the importance of sample size. J Bronchology Interv Pulmonol. 2019;42:e30.
3. Ault MJ, Rosen BT, Scher J, et al. Thoracentesis outcomes: a 12-year experience. Thorax. 2015;70:127–132.
4. Jones PW, Moyers JP, Rogers JT, et al. Ultrasound-guided thoracentesis: is it a safer method? Chest. 2003;123:418–423.
5. Patel PA, Ernst FR, Gunnarsson CL. Ultrasonography guidance reduces complications and costs associated with thoracentesis procedure. J Clin Ultrasound. 2012;40:135–141.
6. Gordon CE, Feller-Kopman D, Balk EM, et al. Pneumothorax following thoracentesis: a systematic review and meta-analysis. Arch Intern Med. 2010;170:332–339.
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