Communications to the Editor |

Revisiting Thoracentesis Procedures FREE TO VIEW

William G. Petersen, MD, FCCP
Author and Funding Information

Scott & White Clinic Temple, TX

Correspondence to: William G. Petersen, MD, FCCP, Scott & White Clinic, 2401 South 31st St, Temple, TX 76508

Chest. 2002;121(3):1008-1009. doi:10.1378/chest.121.3.1008
Text Size: A A A
Published online

To the Editor:

I would like to reply to the issues raised by Dr. Fee in his recent letter (July 2001).1I was impressed by his very low rate of pneumothorax. Since pneumothorax can only occur at an integral rate, a rate of only 0.025%, as reported by Dr. Fee in his letter, would imply an occurrence of five pneumothoracesis out of 20,000 procedures. By my calculation, it would require only 54.7 years to accumulate this series if one performed a single thoracentesis every day of the year with no time off for weekends or holidays, leap years not withstanding. If one took a slightly more conservative interpretation of his number, then the rate would be one out of 5,000. This would still require 13.7 years to accomplish at the rate described above. For the more usual 5-day work week, at a rate of one every day (without fail), this would still require 19.2 years. In our study2 at a relative large tertiary center with eight active pulmonologists, there were only slightly > 300 thoracenteses (including all inpatients and outpatients) performed in 2 years. We would have had to continue our study for 16 years to accumulate that series of 5,000. There can be only one conclusion. Dr. Fee does not have an accurate accounting of the number of thoracenteses he has performed. That very fact raises a significant question as to the validity of his estimation of the number of complications that have followed this purported number of thoracenteses. He does not and, in fact, can not provide any reliable data to support the implied safety of using a vacuum bottle for the removal of pleural fluid. Our study, however, clearly demonstrated the increased risk associated with the use of the vacuum bottle.

Dr. Fee’s comments concerning the use of aspiration tubing as a manometer are unclear and flawed. The inclusion of the photos and the insertion of parentheses in the published letter1 do clarify the situation somewhat, compared to the letter (devoid of photos) that was forwarded to me for consideration. However, even in the photos, it is not clear that the end of the tubing is open to the atmosphere, as this would be the proper fashion to reference the pleural pressure. If the tubing is left connected to the vacuum bottle during the “measurement of the pleural pressure,” then the determination is meaningless.

The pleural space is negative relative to atmosphere when the lung is at functional residual capacity. I should not have to expound on that concept, as there are a multitude of physiologists who have written on this with far more eloquence than I could hope to display. His assertion that “one cannot have a negative space” only reflects a lack of clear understanding of pleural space mechanics. I agree that an extremely negative pleural pressure resulting from a noncompliant lung subjected to a vacuum device would likely increase the risk of pneumothorax. I would refer Dr. Fee to a very excellent article3 which discusses a more precise method to measure pleural pressure and which details the behavior of pleural pressure as fluid is withdrawn from the pleural cavity. %With regard to the predictive value of foam in the vacuum bottle, Dr. Fee offers not scientific proof, but rather his own belief that this observation in some fashion relates to the degree of vacuum remaining in the bottle. The occurrence of foaming is a complex issue related to the surface tension of the fluid, dissolved gases, and turbulent flow through the tubing and needle orifice as fluid enters the vacuum bottle. Bubbling in the static fluid would cease once the partial pressure of the gas in the air above the fluid was equal to the partial pressure of the dissolved gases, minus the resisting forces of surface tension. This does not require that the pressure in the bottle be atmospheric. The lack of bubbles does not indicate “no vacuum.” I would challenge Dr. Fee to collect data on the use of the vacuum bottle and to correlate “nonfoaming” with the occurrence of pneumothorax. Obviously, to achieve statistical significance in any reasonable length of time will require a substantial increase in his complication rate.

The recommendation for needle thoracostomy for treatment of post-thoracentesis pneumothorax is based on faulty understanding of the pathophysiology. The pneumothorax is not likely due to a direct puncture of lung, but rather to the evacuation of a pleural space and to the tearing of a noncompliant visceral pleura and underlying lung. As noted in our study, at least 50% of the pneumothoraceses required no intervention at all. To subject the patient to a needle thoracostomy for a small pneumothorax is simply to perform a needless procedure. I would also wonder how one can make this recommendation based on a pneumothorax rate of one out of 5,000 at best (see discussion above).

I would agree that appreciation of the asymmetric intensity of breath sounds is at times difficult. I utilize both simple auscultation, during a full ventilatory cycle, and vocal fremitus to assess for pneumothorax. However, determining which is “a much better test” would not only require a vast number of subjects with a pneumothorax but would also be quite operator dependent.

In summary, we conducted our study because of disparities of practice, largely based on nonscientific opinions such as those expressed by Dr. Fee. We hoped to provide scientific knowledge that would serve as the foundation for policies. Much is said about the performance of thoracentesis; much is based on tradition and custom. When standards are proposed by professional organizations (ie, the American Thoracic Society) by which we, the physicians, will find ourselves judged by nonmedical persons (ie, lawyers), then these standards should be based on strong, scientific outcomes analysis, not on legends and myths. I am concerned that the publication of the letter by Dr. Fee will result in suboptimal performance of thoracentesis and will further propagate misunderstanding of the mechanics of pleural effusions, the compliance of the pleural space, and the occurrence of pneumothorax after thoracentesis.

Fee, WH (2001) Performing thoracentesis [letter].Chest120,322. [CrossRef]
Petersen, W, Zimmerman, R Limited utility of chest radiograph after thoracentesis.Chest2000;117,1038-1042. [PubMed]
Villena, V, Lopez-Encuentra, A, Pozo, F, et al Measurement of pleural pressure during therapeutic thoracentesis.Am J Respir Crit Care Med2000;162,1534-1538. [PubMed]




Fee, WH (2001) Performing thoracentesis [letter].Chest120,322. [CrossRef]
Petersen, W, Zimmerman, R Limited utility of chest radiograph after thoracentesis.Chest2000;117,1038-1042. [PubMed]
Villena, V, Lopez-Encuentra, A, Pozo, F, et al Measurement of pleural pressure during therapeutic thoracentesis.Am J Respir Crit Care Med2000;162,1534-1538. [PubMed]
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

  • CHEST Journal
    Print ISSN: 0012-3692
    Online ISSN: 1931-3543