Correspondence
Thoracentesis
N Engl J Med 2007; 356:641-642February 8, 2007
- Article
To the Editor:
Thomsen et al. (Oct. 12 issue)1 state in their video that thoracentesis must be performed with “extreme care” in mechanically ventilated patients because of a theoretically increased risk of tension pneumothorax. They also state that chest radiographs should be routinely performed if “the patient is critically ill or receiving mechanical ventilation.”
Although care is appropriate in any invasive procedure, pneumothorax is a rare complication as long as ultrasonography is used. In a series of 232 mechanically ventilated patients, 3 patients (1.3%) had pneumothorax.2 None of these pneumothoraxes were under tension, although a chest tube was inserted in all three cases.
This low rate of pneumothorax may indicate that postprocedure radiography is not routinely indicated after thoracentesis guided by ultrasonography. In addition, if pneumothorax is to be ruled out, ultrasound documentation of lung sliding may be superior to chest radiography.3
3 ReferencesLewis A. Eisen, M.D.
Beth Israel Medical Center, New York, NY 10003
leisen@gmail.com 1
Thomsen TW, DeLaPena J, Setnik GS. Thoracentesis. N Engl J Med 2006;355:e16.
2
Mayo PH ,Goltz HR ,Tafreshi M ,Doelken P . Safety of ultrasound-guided thoracentesis in patients receiving mechanical ventilation. Chest 2004;125:1059-1061
CrossRef | Web of Science | Medline3
Lichtenstein DA ,Meziere G ,Lascols N , et al. Ultrasound diagnosis of occult pneumothorax. Crit Care Med 2005;33:1231-1238
CrossRef | Web of Science | Medline
To the Editor:
The video about thoracentesis by Thomsen et al. was well prepared and is educational for medical trainees unfamiliar with the procedure. However, it perpetuates a misconceived distinction between diagnostic and therapeutic thoracentesis.
After a patient has been subjected to the risks and discomfort of catheter insertion, there is no benefit of leaving fluid within the chest. The risks of bleeding or pneumothorax, once the needle has been removed, should be unchanged, regardless of the quantity of fluid aspirated. Withdrawing “diagnostic” quantities and leaving large residual effusions subjects the patient to continued dyspnea and future additional procedures. It is important to limit the risk of reexpansion pulmonary edema (by aspiration of <1.5 liters, according to the authors). Within that constraint, all accessible fluid should be removed.
This illogical and detrimental differentiation between diagnostic and therapeutic thoracentesis should be abolished. All thoracenteses should be both diagnostic and therapeutic.
Roy T. Temes, M.D., M.B.A.
Cleveland Clinic, Cleveland, OH 44109
temest@ccf.org Author/Editor Response
We are hesitant to conclude that post-thoracentesis chest radiography should be omitted in critically ill or mechanically ventilated patients, even if ultrasonography is used. Although Mayo et al. reported a pneumothorax rate of 1.3%,1 Barnes et al. reported 15 pneumothoraxes in 305 ultrasound-guided procedures (4.9%),2 and Gervais et al. reported 6 pneumothoraxes in 90 ultrasound-guided procedures (6.7%) in mechanically ventilated patients.3 Pneumothorax may be considered rare, but it is prevalent enough to warrant consideration.
In the retrospective review of thoracentesis by Alemán et al., clinical symptoms such as cough, dyspnea, and pleuritic chest pain were the main indicators of the presence of pneumothorax.4 These findings may be missed (or absent) in critically ill or intubated patients. Furthermore, simple pneumothorax may rapidly progress to tension pneumothorax in mechanically ventilated patients,5 and thus early diagnosis may prevent substantial clinical deterioration.
The use of ultrasonography in lieu of chest radiography to diagnose pneumothorax is intriguing. However, given the operator-dependent nature of ultrasonographic studies, this approach may not be widely applicable, especially for those who are unfamiliar with the technique.
We agree with Temes that if thoracentesis is to be performed, there is no rationale for “withdrawing `diagnostic' quantities and leaving large residual effusions.” However, his claim of an “illogical and detrimental differentiation between diagnostic and therapeutic” procedures seems overstated. In many cases, either diagnostic or therapeutic considerations alone lead to thoracentesis. For example, in a patient with progressive constitutional symptoms (but without respiratory symptoms), a moderate-size pleural effusion may be noted on chest radiography. Thoracentesis is indicated in this situation for diagnostic purposes. Conversely, a patient with a history of pleural effusion with a known cause (e.g., chylothorax) may present with respiratory distress and a large effusion. In this situation, thoracentesis is performed primarily as a therapeutic procedure.
5 ReferencesTodd W. Thomsen, M.D.
Gary S. Setnik, M.D.
Mount Auburn Hospital, Cambridge, MA 02238
tthomsen@mah.harvard. edu 1
Mayo PH ,Goltz HR ,Tafreshi M ,Doelken P . Safety of ultrasound-guided thoracentesis in patients receiving mechanical ventilation. Chest 2004;125:1059-1061
CrossRef | Web of Science | Medline2
Barnes TW ,Morgenthaler TI ,Olson EF ,Hesley GK ,Decker PA ,Ryu JH . Sonographically guided thoracentesis and rate of pneumothorax. J Clin Ultrasound 2005;33:442-446
CrossRef | Web of Science | Medline3
Gervais DA ,Petersein A ,Lee MJ ,Hahn PF ,Saini S ,Mueller PR . US-guided thoracentesis: requirement for postprocedure chest radiography in patients who receive mechanical ventilation versus patients who breathe spontaneously. Radiology 1997;204:503-506
Web of Science | Medline4
Aleman C ,Alegre J ,Armadans L , et al. The value of chest roentgenography in the diagnosis of pneumothorax after thoracentesis. Am J Med 1999;107:340-343
CrossRef | Web of Science | Medline5
Leigh-Smith S ,Harris T . Tension pneumothorax -- time for a re-think? Emerg Med J 2005;22:8-16
CrossRef | Web of Science | Medline
