Routine Pleural Manometry Doesn't Prevent Complications After Large-Volume Thoracentesis

By Will Boggs MD

March 01, 2019

NEW YORK (Reuters Health) - Routine pleural manometry does not prevent pleural-pressure-related complications after therapeutic large-volume thoracentesis, according to results from a randomized controlled trial.

"Pleural manometry, conceptually, should allow us to predict complications during thoracentesis shown to be secondary to excessively negative pleural pressure," said Dr. Fabien Maldonado from Vanderbilt University School of Medicine, in Nashville, Tennessee.

"Clearly, this does not appear to be the case, and, therefore, the assertion that pleural manometry should be routinely used during therapeutic thoracentesis is not supported by the data," he told Reuters Health by email.

Large-volume (>1.5 L) thoracentesis is associated with higher complication rates, and several complications have been associated with increasingly negative pleural pressures (lower than -20 cm H2O). Pleural manometry monitoring is commonly used with the aim of mitigating pressure-related risks, and some studies have suggested that aspiration of larger volumes is safe if manometry is used.

Dr. Maldonado and colleagues investigated whether monitoring of pleural pressure with manometry during thoracentesis could protect against complications, compared with assessment of symptoms during fluid aspiration, in their randomized trial of 124 patients who were referred for therapeutic thoracentesis.

The primary outcome, overall procedural chest discomfort rated at five minutes after the procedure, did not differ significantly between the manometry and control groups, they report in The Lancet Respiratory Medicine, online February 13.

There were no significant differences between the manometry and control groups for any of the secondary outcome measures, including chest discomfort and breathlessness during or after the procedure.

"Pleural manometry does not appear to decrease complications related to excessively negative pleural pressures at this time, and, therefore, its routine use is not recommended," Dr. Maldonado said. "We are left wondering how much fluid can safely be withdrawn at one time."

"The British Thoracic Society guidelines recommend that no more than 1,500 mL be drained at once," he said. "Based on our results, we do not feel that this recommendation is supported by our data either and would suggest, based on our results, that careful attention to patient symptoms (specifically discomfort associated with negative pleural pressure, typically felt anteriorly and sometimes in the neck) should allow safe drainage of large volumes of fluid."

"Real-time pleural pressure measurements are currently being investigated by several research teams and may address the current technical limitations of pleural manometry," Dr. Maldonado added. "We will continue our research and hopefully continue to clarify the optimal technique for thoracentesis, one of the most commonly performed procedures in medicine."

Dr. Rafal Krenke from the Medical University of Warsaw, Poland, who co-authored an accompanying editorial, told Reuters Health by email, "The overall negative results of the study are interesting and intriguing at the same time. The authors presented some reasonable explanation for their result, and, in my opinion, the volume of withdrawn pleural fluid should be emphasized when interpreting the results. The volume of removed pleural fluid was smaller than 1.0 L in about 40% of patients. A relatively moderate or even a small volume of removed pleural effusion in numerous patients participating in the study may be an important factor explaining the negative study results."

"I still believe pleural manometry might be useful during therapeutic thoracentesis," he said. "If the manometry is applied with intention to prevent procedure-related complications, I would use it in 1) patients with true large-volume thoracentesis (>1.0 or 1.5 L); 2) patients who earlier experienced some complications, e.g. dyspnea, chest pain; and 3) patients with high risk of trapped lung."

"If the manometry is used as a method to measure the mechanical properties of the lung and pleura (assess the lung expandability, measure the pleural elastance), it should be used in all patients in whom this information is relevant, e.g., those who seem to be candidates for pleurodesis," Dr. Krenke said.

"Further studies should be undertaken to define the selection criteria for patient who can benefit from pleural manometry in terms of the thoracentesis safety," he said.

Dr. David Feller-Kopman from Johns Hopkins University School of Medicine, in Baltimore, Maryland, who has advocated the use of manometry during thoracentesis, told Reuters Health by email, "We still don't know the answer to (which patients should have pleural manometry), and the role of manometry is likely more significant in patients in whom large volumes (>1.5L) of fluid are removed."

"Manometry is not needed for draining effusions less than 1-1.5 L, though we need to await future trials to see if it will be helpful in 'large-volume' thoracenteses," he said.

Centurion Medical Products, which manufactures the single-use digital manometer used in this study, supported both study through an unrestricted educational grant.

SOURCE: https://bit.ly/2SykZJE and https://bit.ly/2BSkiFh

Lancet Respir Med 2019.

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