Pulmonary fluid or pleural effusion – causes, diagnosis and treatment explained clearly

Causes and frequency of pleural effusions

A pleural effusion can be caused by benign or malignant processes. Common causes include heart failure (cardiac insufficiency), pneumonia, pulmonary embolism or liver cirrhosis – these usually lead to transudative effusions (fluid due to pressure or protein changes). Exudative effusions are caused by inflammation or tumors. Malignant pleural effusions occur especially in advanced cancer, most commonly in lung cancer, breast cancer, or tumors of the pleura (lining of the lung). An estimated up to 150,000 malignant pleural effusions per year are diagnosed in the USA alone. Overall, approximately Every sixth cancer patient develops a pleural effusion during the course of their disease, which underscores the high relevance of this symptom. Malignant effusions are a sign of advanced tumor disease and are associated with a limited prognosis.

Symptoms and diagnostics

The main symptom of a pleural effusion is shortness of breath – the lung can no longer expand freely due to the fluid. Many affected individuals also notice a dry, irritating cough and a feeling of pressure or pain in the chest. The symptoms of malignant effusions can increase in a short time, as fluid often re-accumulates rapidly.

For diagnostics a physical examination is performed first. The chest X-ray typically shows a shadowing in the lower lung fields in the case of a larger effusion. Even more sensitive is the Ultrasound examination of the thorax, which can detect even smaller amounts of fluid. Ultrasound also helps to perform a safe puncture. Thorax CT (computed tomography) and in special cases PET-CT can provide further indications of tumor infestation of the pleura.

The most important diagnostic measure is the pleural puncture (thoracentesis): Under local anesthesia, a needle is inserted into the pleural space to remove fluid. This is examined in the laboratory for signs of inflammation, protein content, and Tumor cells (cytology) . In approximately 60–75% of malignant effusions, it is possible to detect cancer cells in the effusion by puncture alone. If the puncture alone is not sufficient (e.g., if the cytology does not provide a clear result), a Pleural biopsy may be necessary – either with a special needle through the chest wall or by means of thoracoscopy.

Importance of thoracoscopy (pleuroscopy) for confirming the diagnosis

The thoracoscopy is a reflection of the chest cavity: A thin endoscopic instrument (video thoracoscope) is inserted under vision into the pleural space via a small incision. This procedure allows direct viewing of the pleura and targeted tissue samples to be taken. Thoracoscopy has a very high diagnostic yield, especially in malignant pleural effusion. Studies show that the diagnostic Accuracy of a thoracoscopic pleural biopsy can be well over 90%. In comparison, a “blind” pleural biopsy or puncture alone often remains without result. Therefore, medical guidelines recommend in case of unclear cause of a unilateral pleural effusion Thoracoscopy, provided there are no contraindications.

A further advantage of thoracoscopy is that if it is already apparent during the procedure that a malignant effusion is present, it is possible to therapeutic can be undertaken directly – for example, a complete drainage of the drainage of the fluid and, if necessary pleurodesis (gluing, see below). Modern thoracoscopy procedures even manage with a single access (“uniportals” thoracoscopy). These can increasingly also be performed under local anesthesia and sedation, i.e. without general anesthesia and without intubation, to be performed. Initial studies show that this “awake VATS”-Technique (video-assisted thoracoscopy on the awake, spontaneously breathing patient) is similarly successful and safe in experienced surgeons as conventional thoracoscopy under general anesthesia. This represents a gentle alternative for patients with a high anesthesia risk.

Molecular diagnostics and predictive markers in pleural oncology

In modern oncology, tumor tissue is increasingly tested for molecular changes examined in order to use targeted therapies. In lung cancer patients with pleural effusion, it is often possible to use the tumor material contained in the pleural fluid for this purpose. Genetic markers such as EGFR mutations or ALK translocations in lung cancer can now be reliably determined from tumor cells contained in the effusion or even from cell-free DNA of the effusion fluid. This often allows a therapy tailored to the individual tumor to be planned without the need for an invasive tissue biopsy of the lung. Also in Pleural mesothelioma (pleural cancer) and other tumors are searched for characteristic biomarkers – such as mesothelin or fibulin-3 in the blood or pleural effusion, which may be elevated in mesothelioma. Such markers can support the diagnosis and sometimes provide information on the course, but do not replace histological confirmation by biopsy.

Also for the forecast assessment in malignant pleural effusion, there are scoring systems that combine clinical and laboratory markers. An example is the LENT scorethe LDH value, ECOG status (general condition), Neutrophil content and Ttumor type to estimate life expectancy in MPE. Overall, molecular and clinical markers are increasingly incorporated into decision-making, such as whether local effusion therapy should be performed primarily or systemic cancer treatment should take precedence.

Treatment options for pleural effusion

The therapy depends on the cause and symptoms of the pleural effusion. Smaller effusions without severe symptoms can often be observed initially and treated conservatively (e.g., therapy of the underlying disease, draining drugs for heart failure). Larger effusions or malignant effusions usually require invasive therapy to quickly relieve shortness of breath. The following procedures are available:

• Therapeutic pleural puncture: Here, fluid is withdrawn with a needle or cannula – similar to diagnostic puncture. This often immediately provides air and reduces shortness of breath. However, in malignant causes, the effusion often refills in days to a few weeks, so another puncture may be necessary.
• Thoracic drainage: A drainage is often placed for pronounced effusion amounts. The doctor inserts a thin tube into the pleural space through a small incision, which is connected to a negative pressure system. This allows fluid to drain continuously. A drainage often remains in place for several days until the effusion formation decreases or another measure is taken.
• Pleurodesis (adhesion): In order to prevent the recurrence of an effusion, a pleurodesis is aimed for. In doing so, an irritating substance is introduced into the pleural space, which causes an inflammatory reaction, so that the lung and parietal pleura adhere to each other and the gap glued. Talcum pleurodesis is the most proven method here – talc powder is introduced via the drainage or by means of thoracoscopy and leads to a permanent adhesion in over 80–90% of cases. Alternatively, drugs such as bleomycin or tetracycline have also been used, but with a slightly lower success rate. It is important that the lung can be expanded (no “trapped lung”), as otherwise complete bonding is not possible.
• Video-assisted thoracoscopic surgery (VATS): The thoracoscopy described above can be used not only for diagnostics, but also for therapy at the same time. As part of a VATS procedure, the effusion can be completely suctioned off, adhesions can be released and – if necessary – visible tumor nodules on the pleura can be removed or reduced (so-called Pleurectomy or decortication). At the end of the procedure, a talc pleurodesis is often performed and a drainage is inserted. The VATS technique is minimally invasive and usually requires only 1–2 small incisions. New developments such as the uniportale VATS require only a single access and are now also performed by some centers without general anesthesia (see above). As a result, the procedure can be made more gentle in selected cases and the recovery time can be shortened.
• Indwelling pleural catheter (permanent drainage): Another established option, especially for patients with shorter life expectancy or recurrent malignant effusionsis the insertion of a permanent pleural catheter. This is a thin tube that is tunneled under the skin and can remain in place for weeks to months. It can be drained regularly at home by the patient or caregiver (outpatient effusion drainage). Studies – like the big MIST and AMPLE studies – have shown that such a pleural catheter offers comparable symptom relief as talc pleurodesis. An advantage is that no inpatient readmissions are necessary for repeated punctures. Sometimes, with prolonged catheter dwell time, spontaneous adhesion (pleurodesis) occurs due to permanent drainage. The current British Guideline 2023 recommends such an IPC (intercostal pleural catheter) now as an equivalent first-line option in addition to the classic pleurodesis. Which method is chosen depends heavily on the individual circumstances, the likely prognosis, and the patient’s wishes.

Outpatient and modern therapy approaches

In recent years, the treatment of malignant pleural effusion has increasingly shifted towards gentle, outpatient procedures developed. Where longer hospital stays for repeated drainages or surgical procedures were often necessary in the past, today pleural catheters and “awake” thoracoscopy techniques enable care partly in the outpatient area. For selected patients, for example, a thoracoscopy under local anesthesia and the patient leaves the clinic on the same day after a short period of monitoring. Tunnel entrances for permanent drainage are placed under local anesthesia and then further cared for at home as part of palliative care. It is important to have close consultation between pulmonologists, thoracic surgeons and outpatient care services in order to control symptoms well at all times.

Nevertheless, the crucial role of systemic cancer therapy exist: A malignant effusion is an expression of the tumor disease, therefore chemotherapy, immunotherapy or targeted therapy (such as against EGFR, ALK mutations) aims to also reduce effusion formation. In some types of tumors, the effusion may be absent or become smaller for a longer period of time under effective systemic therapy. However, experience shows that Local measures on the effusion almost always necessary are to quickly provide air and improve the quality of life. Modern pleural oncology therefore pursues an individual approach: Depending on the patient’s prognosis and Expandability of the lung (radiologically assessable), a tailored plan is drawn up – be it initially a pleurodesis, a permanent drain, or primarily tumor therapy, accompanied by symptomatic effusion punctures.

Conclusion

Pleural effusions – especially malignant pleural effusions – pose challenges for patients and physicians. Thanks to advanced diagnostic procedures such as thoracoscopy and modern therapy concepts (talc pleurodesis, permanent drainages, minimally invasive VATS even without intubation), effective help can usually be provided today. The primary goal is the Relief of breathlessness and improvement in quality of life. At the same time, molecular diagnostics on the effusion allows the underlying tumor disease to be treated more and more specifically. Close interdisciplinary cooperation between oncology, pneumology and thoracic surgery is crucial in order to find the optimal combination of local effusion control and systemic therapy can be found.

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