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Point: Should Pleural Manometry Be Performed Routinely During Thoracentesis? Yes

2012; Elsevier BV; Volume: 141; Issue: 4 Linguagem: Inglês

10.1378/chest.11-3231

1931-3543

David Feller‐Kopman,

Ultrasound in Clinical Applications

functional residual capacity reexpansion pulmonary edema When deciding to incorporate a new procedure into clinical practice, it is essential to carefully evaluate the reasons for doing so. The procedure should ideally add useful clinical information that will impact management, be easy to perform, have few risks to the patient, and not add significant costs to the care of the patient. The routine use of pleural manometry to thoracenteses satisfies all of these requirements and should be performed with every thoracentesis. There are approximately 1.5 million patients diagnosed with pleural effusions each year in the United States, making thoracentesis one of the most commonly performed medical procedures.1Light RW Pleural Diseases. 4th ed. Lippincott Williams & Wilkins, Philadelphia, PA2001Google Scholar Although investigations of pleural pressures have been undertaken for > 120 years,2Quincke H Ueber den Druck in Transudaten.Dtsch Arch Klin Med. 1878; 21: 453-468Google Scholar the clinical use of pleural manometry has become more popular only over the last 3 decades. The measurement of pleural pressure during thoracentesis provides information regarding both the cause of the effusion and the ability of the lung to expand as fluid is withdrawn. Pleural fluid formation is dependent on the balance of hydrostatic and oncotic pressures between the pleural space and the visceral and parietal pleural capillaries. In the normal thorax, at functional residual capacity (FRC), pleural pressure is slightly subatmospheric, approximately −3 to −5 cm H2O. This results from the equilibrium achieved by the elastic recoil forces of the lung and the tendency of the chest wall to expand. As fluid accumulates in the pleural space, pleural pressure typically rises. This, however, is dependent on the cause of the effusion, as diseases that cause a drop in pleural pressure will clearly increase the hydrostatic gradient for pleural fluid formation. Likewise, as pleural fluid is removed, one would expect the lung to expand, the chest wall to contract, and pleural pressure to reach its steady state at FRC. The ability for the lung to expand, however, can greatly affect pleural pressure, especially toward the terminal portion of the thoracentesis. The measurement of pleural pressure is the only way to assess the underlying physiology of the lung and pleural space and provides clinically useful information regarding the cause of the effusion, minimizes pressure-related complications of thoracentesis, and can predict the success of pleurodesis in patients with malignant pleural effusions. There are three distinct pleural elastance curves that one can appreciate during a thoracentesis (Fig 1).3Light RW Jenkinson SG Minh VD George RB Observations on pleural fluid pressures as fluid is withdrawn during thoracentesis.Am Rev Respir Dis. 1980; 121: 799-804PubMed Google Scholar, 4Feller-Kopman D Parker MJ Schwartzstein RM Assessment of pleural pressure in the evaluation of pleural effusions.Chest. 2009; 135: 201-209Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar In the first curve (normal physiology), pleural pressure is positive, and as fluid is withdrawn, pleural pressure approaches −3 to −5 cm H2O at FRC. This elastance curve is typical of effusions due to hepatic hydrothorax or congestive heart failure. In the second curve, termed "lung entrapment," the initial elastance is normal, but toward the terminal portion of the thoracentesis the pressure drops and the slope of the curve becomes steeper. This is due to failure of the lung to fully expand and can be seen in patients who have a visceral pleural peel, endobronchial obstruction, or any cause of increased elastic recoil pressures of the lung parenchyma, such as lymphangitic carcinomatosis. This curve is commonly encountered in patients with malignant pleural effusions, occurring in up to 32% of patients in the largest study of pleurodesis to date.5Dresler CM Olak J Herndon II, JE Cooperative Groups Cancer and Leukemia Group B; Eastern Cooperative Oncology Group; North Central Cooperative Oncology Group; Radiation Therapy Oncology Group et al.Phase III intergroup study of talc poudrage vs talc slurry sclerosis for malignant pleural effusion.Chest. 2005; 127: 909-915Abstract Full Text Full Text PDF PubMed Scopus (432) Google Scholar Additionally, it has been shown that the success of pleurodesis in these patients is significantly lower than in patients with a fully expandable lung.6Lan RS Lo SK Chuang ML Yang CT Tsao TC Lee CH Elastance of the pleural space: a predictor for the outcome of pleurodesis in patients with malignant pleural effusion.Ann Intern Med. 1997; 126: 768-774Crossref PubMed Scopus (117) Google Scholar Although nonexpandable lung can be identified by postthoracentesis imaging, there are several mechanisms of pneumothorax following thoracentesis,7Heidecker J Huggins JT Sahn SA Doelken P Pathophysiology of pneumothorax following ultrasound-guided thoracentesis.Chest. 2006; 130: 1173-1184Abstract Full Text Full Text PDF PubMed Scopus (88) Google Scholar and manometry is a useful and easy way to identify lung entrapment as the cause. Furthermore, manometry has been used to safely guide large-volume thoracenteses.8Villena V López-Encuentra A Pozo F De-Pablo A Martín-Escribano P Measurement of pleural pressure during therapeutic thoracentesis.Am J Respir Crit Care Med. 2000; 162: 1534-1538Crossref PubMed Scopus (73) Google Scholar, 9Feller-Kopman D Berkowitz D Boiselle P Ernst A Large-volume thoracentesis and the risk of reexpansion pulmonary edema.Ann Thorac Surg. 2007; 84: 1656-1661Abstract Full Text Full Text PDF PubMed Scopus (183) Google Scholar The benefits of removing as much fluid as possible include maximizing symptom relief, maximizing the usefulness of postprocedure imaging, and identifying the terminal nonexpandable lung prior to attempts at pleurodesis. If one only removes 1 of 3 L in the thorax and assumes the rest of the lung will expand at the time of pleurodesis, the patient may be exposed to a procedure that will not be successful. These patients with lung entrapment due to malignant pleural effusions can be effectively managed with tunneled pleural catheters,10Tremblay A Michaud G Single-center experience with 250 tunnelled pleural catheter insertions for malignant pleural effusion.Chest. 2006; 129: 362-368Abstract Full Text Full Text PDF PubMed Scopus (314) Google Scholar and in fact, the spontaneous pleurodesis rate for tunneled pleural catheters is likely higher in patients with full lung expansion as compared with patients with nonexpandable lung.11Tremblay A Mason C Michaud G Use of tunnelled catheters for malignant pleural effusions in patients fit for pleurodesis.Eur Respir J. 2007; 30: 759-762Crossref PubMed Scopus (95) Google Scholar Finally, the third curve describes another cause of nonexpandable lung, termed "trapped lung." Patients with trapped lung have pleural effusions ex vacuo—the negative pleural pressure is the cause of the effusion. These effusions are transudates, and as patients are often asymptomatic, specific therapy aimed at the effusion is not typically required. There are several ways to measure pleural pressures at the bedside, and these have been reviewed in detail.4Feller-Kopman D Parker MJ Schwartzstein RM Assessment of pleural pressure in the evaluation of pleural effusions.Chest. 2009; 135: 201-209Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar, 12Doelken P Huggins JT Pastis NJ Sahn SA Pleural manometry: technique and clinical implications.Chest. 2004; 126: 1764-1769Abstract Full Text Full Text PDF PubMed Scopus (68) Google Scholar The simplest and least expensive method is to use the syringe-pump system that is part of standard thoracentesis kits as a U-shaped manometer. Another advantage of using the syringe-pump method is an associated lower pneumothorax rate when compared with using a vacuum bottle.13Petersen WG Zimmerman R Limited utility of chest radiograph after thoracentesis.Chest. 2000; 117: 1038-1042Abstract Full Text Full Text PDF PubMed Scopus (71) Google Scholar This likely results from the fact that a vacuum bottle will continue to drain, even in the setting of a nonexpandable lung, whereas the operator typically will stop drainage either as the pleural pressure falls significantly or at the first signs of aspirating air. With the syringe-pump/U-shaped manometer technique, no additional expenses or risks are added to the procedure. It is also extremely easy to perform and, depending on the volume of fluid removed, adds only seconds to a few minutes to the duration of the procedure. One should be able to appreciate that measurement of pleural pressure satisfies all necessary criteria for incorporating a new procedure into practice: It adds clinically useful information and is easy, inexpensive, and without risk. As there are no downsides to pleural manometry, it should be considered a routine part of every thoracentesis.