Can more than two liters of pleural effusion be aspirated?

From the Guidelines

It is not recommended to draw more than 1-1.5 liters of pleural fluid at one time due to the risk of re-expansion pulmonary edema (RPE). When large volumes of fluid are rapidly removed from the pleural space, the sudden re-expansion of the compressed lung can cause increased capillary permeability, leading to pulmonary edema 1. This complication, while rare, can be life-threatening. If a patient has a large pleural effusion requiring drainage of more than 1.5 liters, it is safer to remove the fluid gradually, either through multiple thoracentesis procedures spaced over time or by placing a pleural catheter for slower, controlled drainage.

Some key points to consider when performing a therapeutic thoracentesis include:

• Monitoring the patient for symptoms such as chest pain, cough, or shortness of breath, which may indicate the development of RPE 1
• Stopping fluid removal when the pleural pressure drops below -20 cm H2O, which requires pressure monitoring during the procedure 1
• Limiting the amount of fluid drained per day to avoid rapid re-expansion of the lung 1
• Using high volume, low pressure systems for suction, if necessary, with a gradual increment in pressure to about –20 cm H2O 1

The risk of RPE can be minimized by controlled drainage of large pleural effusions, avoiding evacuation of more than 1–1.5 l at one time or slowing to about 500 ml/hour, and discontinuing aspiration if the patient develops chest discomfort, persistent cough, or vasovagal symptoms 1.

In terms of morbidity, mortality, and quality of life, the goal is to provide relief from symptoms while minimizing the risk of complications. Gradual removal of pleural fluid, either through multiple thoracentesis procedures or by placing a pleural catheter, is the recommended approach for patients with large pleural effusions. This approach can help to reduce the risk of RPE and other complications, while also improving the patient's quality of life by relieving symptoms such as dyspnea and chest discomfort 1.

From the Research

Drawing More Than Two Liters of Pleural Fluid

• The study 2 found that large-volume thoracentesis (> or = 1 L) can be performed with a low risk of reexpansion pulmonary edema (RPE), and the incidence of RPE is not associated with the volume of fluid removed.
• In the study 2, 185 patients underwent large-volume thoracentesis, with 38 patients having between 2 L and 3 L withdrawn, and 9 patients having more than 3 L withdrawn, with only 1 patient experiencing clinical RPE.
• The results of the study 2 suggest that the recommendation to terminate thoracentesis after removing 1 L of fluid may need to be reconsidered, and large effusions can be drained completely as long as certain conditions are met.

Clinical Considerations

• The study 3 highlights the importance of precise differential diagnostic categorization of pleural effusion, as the treatment and prognosis depend on the underlying cause.
• The study 4 discusses the effects of pleural effusion on respiratory function, including a restrictive ventilatory effect, chest wall expansion, and reduced efficiency of the inspiratory muscles.
• The magnitude of these alterations depends on the pleural fluid volume and the underlying disease of the respiratory system, as noted in the study 4.

Diagnostic and Therapeutic Considerations

• The study 5 emphasizes the importance of interpreting pleural fluid results correctly, taking into account the possible aetiologies of a pleural effusion and the reliability of each investigation.
• The study 6 investigates the frequency of unexplained pleural effusions in patients with normal and low plasma oncotic pressures, finding that hypoalbuminemia is an uncommon cause of pleural effusion.
• The study 3 discusses the range of therapeutic options for pleural effusion, including pleurodesis, thoracoscopy, and video-assisted thoracoscopy, as well as the placement of a permanently indwelling pleural catheter.