Parapneumonic effusion - loculated

Case contributed by Chris Lim
Diagnosis certain

Presentation

Ten day history of fevers, right-sided pleuritic chest pain, and exertional dyspnea.

Patient Data

Age: 55
Gender: Female

Admission Chest X-ray

x-ray

Small pleural effusion seen at right base with associated compressive atelectasis. Convex opacity representing encysted pleural fluid is seen between right upper and middle lobe(s), along with fluid in the horizontal fissure.

CT Chest

ct

Loculated right-sided pleural effusion. The largest pocket of fluid is present posteriorly at the right lung base, with associated atelectasis and minor consolidation. Encysted pleural fluid is visualized between the right upper and middle lobe(s). Pleural fluid is seen extending to the right oblique fissure.

Solitary mildly prominent right hilar lymph node, without evidence of right hilar mass or focal pulmonary lesion.

Point-of-care lung ultrasound

ultrasound

Point-of-care thoracic ultrasound was performed, demonstrating a longitudinal view of the right lower lobe.

The most prominent finding of this scan is a loculated pocket of pleural fluid that does not otherwise appear to extend inferiorly between the right lower lobe and the diaphragm. The effusion appears to have a mildly echogenic, 'speckled' appearance, which is suggestive of exudative effusion.

Mild compressive atelectasis is seen in lung tissue adjacent to the effusion. Normal A-lines are seen within lung tissue. The right diaphragm, along with the liver, is briefly visualized at the end of the clip.

Inpatient pleural drain insertion had previously been performed through the Radiology department. However, only 20mL of clotted material was able to be aspirated and the drain was subsequently removed.

Following adequate visualization of the loculated pleural effusion using point-of-care lung ultrasound and review of previous imaging, pleural drain insertion was successfully performed by the home team using Seldinger technique.

Post-insertion Chest X-ray

x-ray

PA and lateral X-ray films immediately following pleural drain insertion using Seldinger technique. The intent of drain insertion was to position the tip of the catheter within the posteromedial pleural space in order to drain the largest pocket of fluid. These scans demonstrate satisfactory positioning of the pleural drain as intended.

Note the persistence of encysted pleural fluid, although the border is less well-defined compared to the initial scan.

Post-insertion CT Chest

ct

CT demonstrating interval insertion of a right pleural drain, which appears appropriately positioned. Reduction in size of right sided pleural fluid collection. Persisting moderately-sized effusion. No evidence of pneumothorax.

Pleural fluid revealed an exudate, with a total protein of 47 g/L and pleural fluid LDH of 5254 U/L, satisfying all of Light's criteria. Pleural fluid cytology was negative for malignancy. Pleural fluid cultures were negative. No bacteria were seen on Gram stain.

Following confirmation of satisfactory catheter placement, intra-pleural enzyme therapy was administered (Alteplase/Dornase alfa) according to Therapeutic Guidelines (which borrows its protocol from the MIST2 trial).

Three doses of Alteplase/Dornase alfa were administered, with a total of 800mL pleural fluid drained through this process. The pleural fluid was mildly bloodstained, with moderate amounts of fibrous debris and stranding present.

Medical staff were unable to aspirate or flush the drain when attempting to administer the fourth dose of intra-pleural enzyme therapy. While minimal volumes (<5mL) could be flushed, this resulted in pain. A repeat CT Chest was obtained to exclude kinking of the catheter tube or adverse positioning of the drain.

CT Chest following in...

ct

CT Chest following intra-pleural enzyme Rx

Post-insertion non-contrast computed tomography of the chest confirms appropriate positioning of the right pleural drain without kinking. Minimal fluid remains in this region, which may have contributed to the inability to aspirate fluid from the catheter. Encysted pleural fluid appears similar to previous CT, although improved compared to initial scan.

Post-drain removal imaging

x-ray

PA and lateral X-ray films following removal of pleural drain. No pneumothorax identified. Mild pleural effusion seen on the right, with thickened appearance of the horizontal fissure likely due to movement of fluid into the inter-fissural space following intra-pleural enzyme therapy. Note improved appearances of encysted pleural fluid in the right upper zone.

Following pleural drainage and improvement in the patient's fevers, dyspnea, and chest pain, the patient was later discharged home to complete a course of step-down oral antibiotic therapy.

Case Discussion

Utility of point-of-care ultrasound in pleural effusion

Point-of-care ultrasound can be utilized by clinicians to identify pleural effusion(s) and locate appropriate sites for drainage. Ultrasound-guided thoracentesis is associated with lower rates of complication, including pneumothorax2.

Point-of-care ultrasound allowed for adequate visualization of the loculated effusion. In conjunction with CT imaging and Seldinger technique, these modalities enabled us to introduce the catheter tip into the largest pocket of pleural fluid (posteromedial).

Classification of pleural effusions

Light's criteria is used to determine if pleural effusions are transudative or exudative. In this case, the patient met all three criteria. Pleural fluid is defined as exudative if it meets any of these criteria3.

  1. Pleural fluid protein 47 g/L (greater than 0.5 x serum protein)
  2. Pleural fluid LDH 5254 U/L (greater than 0.6 x serum LDH)
  3. Pleural fluid LDH 5254 U/L (greater than 2/3rds upper limit of normal LDH)

Associated serum values: Total protein 62 g/L, LDH 386 U/L

Intra-pleural enzyme therapy

Intra-pleural enzyme therapy is the least invasive option for drainage of complicated parapneumonic effusion or empyema. A recent 2018 retrospective analysis suggested a 55% response rate to non-surgical therapy in empyema4. Failure of initial intra-pleural enzyme therapy (e.g. partial improvement, complex loculations) to achieve adequate drainage can be followed by additional chest tube insertion, or video-assisted thoracic surgery (VATS). Most studies report successful resolution of the effusion following VATS, surgical procedures are associated with higher rates of chronic pain and major bleeding compared to intra-pleural enzyme therapy5.

The protocol used most widely in Australia is that of the MIST2 trial, published by Rahman et al. in the New England Journal of Medicine in 20111.

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