Approach to Pleural Effusion

Indications for thoracocentesis

·       Diagnostic (new effusion of unclear etiology) for pleural effusion

·       In patients with CHF the following features should prompt thorcocentesis

1.      Features suggestive of an alternate etilogy          - eg BL effusion of significantly disparate sizes

2.      Features suggestive of Pleurisy or fever

3.      Features suggestive of infection or cancer

4.      Echocardiogram not consistent with CHF

5.      Disproportionately wide alveolar arterial O2 gradient

6.      Lack of resolution with effective CHF therapy

·       Therapeutic (symptom relief)

·       Prevention of complications Contraindications for thoracocentesis

·       Insufficient pleural fluid

·       Skin infection or wound at needle insertion site

·       Severe bleeding diathesis

Following thoracocentesis, the following biomarkers should be sent for most pleural effusions

·       Cell counts and differential counts

·       Total protein

·       ADA

·       LDH

·       Glucose

·       Culture

·       Grams stain

·       Cholesterol

·       AFB stain/ CBNAAT

·       Malignant cells

Concurrent testing from serum for the following is required

·       Total protein

·       LDH

·       RBC counts in suspected hemothorax

·       Amylase (rupture of esophagus)

·       Creatinine (urinothorax)

·       Bilirubin (bilothorax)

The following gross observations may be helpful

Classify pleural fluid into transudates and exudates on the basis of Light’s criteria

·       Pleural fluid to serum ration > 0.5

·       Pleural fluid to serum LDH ratio > 0.6

·       Pleural fluid LDH > ).67 i.e >2/3rd the upper limit of normal serum LDH

In cases of

1.      suspected heart failure related pleural effusion on diuretics, 25 – 30% may be

misclassified as exudates by Light’s criteria. In such cases, measure

·       Albumin or total protein gradient

·       Pleural fluid or serum NT-proBNP

2.      Suspected esophageal or pancreatic related effusion

·       Salivary amylase

·       Pleural fluid pH

3.      Suspected chylous or cholesterol effusion

·       Cholesterol and triglyceride levels from plural effusion

·       Rarely, lipoprotein analysis for chylomicrons

4.      Suspected hemothorax

·       Perform hematocrit on fresh sample of pleural fluid and compare with blood hematocrit

5.      Suspected urinothorax

·       Compare pleural fluid and serum creatinine

6.      Suspected ventriculoperitoneal shunt related effusion

·       Beta 2 transferrin

7.      Suspected glycinothorax

·       Compare pleural fluid and serum glycine

8.      Suspected bilothorax

·       Compare pleural fluid and serum bilirubin

In case of unclear etiology, the following steps should be taken

·       Retake history and examination

·       Reanalyze pleural fluid

·       Consider additional imaging like PET/CT etc If etiology is still unclear

·       Do a pleural biopsy

o   Diffuse pleural involvement : closed pleural biopsy

o   Pleural mass or thickening : Image guided pleural biopsy

o   Patchy pleural involvement : thoracoscopic pleural biopsy