Thoracentesis

Volume of pleural fluid

Physical examination findings

<250–300 cm³

Probable normal examination

500 cm³

1. Dullness to percussion

2. Decreased fremitus

3. Normal vesicular breath sounds but decreased intensity

1,000 cm³

1. Absence of inspiratory retraction, mild bulging of intercostal spaces

2. Decreased expansion of ipsilateral chest wall

3. Dullness to percussion up to the scapula and axilla

4. Decreased or absent fremitus posteriorly and laterally

5. Bronchovesicular breath sounds

6. Egophany (E to A change) at the upper level of the effusion

Massive (filling the hemithorax)

1. Bulging of intercostal spaces

2. Minimal to no ipsilateral chest wall expansion

3. Dull or flat percussion

4. Absent breath sounds

5. Egophany at the apex

6. Palpable liver or spleen due to diaphragmatic depression

Chest radiograph can aid in the differential diagnosis. If the effusion is bilateral, it is typically transudative (see below) and due to congestive heart failure, renal failure, or hypoalbuminemia. Cardiac enlargement is frequently seen in congestive heart failure. If a bilateral effusion is found to be exudative (see below), malignancy is most common, but can be seen with lupus pleuritis and rheumatoid pleurisy as well. When an isolated pleural effusion is the only abnormality, the physician should suspect infectious causes such as bacterial or tuberculous infections, in the right clinical setting. Rheumatoid pleurisy and lupus pleuritis can also present with an isolated effusion. Interstitial infiltrates in the setting of a pleural effusion are consistent with volume overload and congestive heart failure, rheumatoid disease, asbestos pulmonary disease, lymphangitic carcinomatosis, sarcoidosis, and lymphangioleiomyomatosis (LAM), among others. Nodular disease suggests malignancy but may also be seen with sarcoidosis and rheumatoid disease (Table 56.2).

Table 56.2

Chest radiograph findings of specific diseases

Chest radiograph findings	Diseases
Unilateral effusion	Infection
	Lupus pleuritis
	Rheumatoid pleurisy
	Metastatic malignancy, non-Hodgkin lymphoma, leukemia
	Pulmonary embolism
	Drug-induced pleural disease
	Yellow nail syndrome
	Hypothyroidism
	Uremic pleuritis
	Chylothorax
	Constrictive pericarditis
With mediastinal shift	Metastatic malignancy
Without mediastinal shift	Lung cancer
Without mediastinal shift	Malignant mesothelioma
Diseases below the diaphragm	Transudative: hepatic hydrothorax, nephritic syndrome, urinothorax, peritoneal dialysis
Diseases below the diaphragm	Exudative: pancreatitis, Meigs syndrome, chylous ascites, subphrenic/hepatic/splenic abscess
Bilateral effusion	Transudative: congestive heart failure, nephrotic syndrome, hypoalbuminemia, peritoneal dialysis, constrictive pericarditis
Bilateral effusion	Exudative: malignancy, lupus pleuritis, rheumatoid pleurisy
Associated with interstitial infiltrates	Congestive heart failure
	Rheumatoid disease
	Asbestos pulmonary disease
	Lymphangioleiomyomatosis (LAM)
	Viral and mycoplasma pneumonia
	Sarcoidosis
	Pneumocystis jiroveci pneumonia
Associated with multiple nodules	Cancer
	Wegener granulomatosis
	Rheumatoid disease
	Septic pulmonary embolism
	Sarcoidosis
	Tularemia

Pleural Fluid Analysis: Briefly

Pleural fluid can establish a definitive diagnosis in a limited number of diseases, such as empyema, malignancy, chylothorax, and rheumatoid pleurisy. However, it is highly useful in excluding potentially harmful diseases that would warrant immediate intervention, such as empyema.

Initial evaluation of the fluid is performed at the time of thoracentesis, as the fluid is aspirated. Careful attention should be paid to the color (straw colored, serosanguinous, bloody, white), consistency (pus, turbid, debris), and odor (foul smelling) of the fluid.

After visual inspection during the procedure, the fluid is sent for laboratory analysis. Broad classification of the fluid into transudative or exudative by chemical analysis is performed (Tables 56.3 and 56.4). Richard Light established a well-known algorithm for distinguishing an exudative pleural effusion based on three tests: (a) pleural fluid lactate dehydrogenase (LDH) >two-thirds the laboratory’s upper limit of normal for serum, (b) pleural fluid to serum LDH ratio >0.6, and (c) pleural fluid to serum protein ratio >0.5. Only one of these results needs to be positive to confirm an exudative effusion. Light’s criteria has a diagnostic accuracy over 90 % but drops significantly to below 70–80 % if one of the three categories is borderline. Pleural fluid can also be analyzed for a number of other laboratory tests, including but not exclusive, to glucose, pH, amylase, cholesterol, albumin, B-type natriuretic peptide (BNP), and adenosine deaminase (ADA). There are many other tests and ways to analyze the pleural fluid from a thoracentesis, but that is outside the scope of this chapter.

Table 56.3

Causes of exudative pleural effusions

Causes
Infectious	Malignancy	Connective tissue disease
Bacterial pneumonia	Carcinoma	Lupus pleuritis
Tuberculous effusion	Lymphoma	Rheumatoid pleurisy
Fungal disease	Mesothelioma	Mixed connective tissue disease
Atypical pneumonias	Leukemia	Sjögren syndrome
Nocardia, Actinomyces	Chylothorax
Subphrenic abscess
Hepatic abscess	Other inflammatory	Endocrine dysfunction
Splenic abscess	Pancreatitis	Hypothyroidism
Hepatitis	BAPE	Ovarian hyperstimulation syndrome
Spontaneous esophageal rupture	Pulmonary infarction
Parasites	Radiation therapy	Lymphatic abnormalities
	Sarcoidosis	Malignancy
Iatrogenic	PCIS	Chylothorax
Drug-induced	Hemothorax	Yellow nail syndrome
Esophageal perforation	ARDS	Lymphangiomyomatosis (chylothorax)
Esophageal sclerotherapy	Cholesterol effusion	Lymphangiectasis
Central venous catheter misplacement/migration
Enteral feeding tube in pleural space
	Increased negative intrapleural pressure	Movement of fluid from abdomen to pleural space
	Atelectasis	Acute pancreatitis
Vasculitis	Trapped lung	Pancreatic pseudocyst
Wegener granulomatosis		Meigs syndrome
Churg–Strauss syndrome		Carcinoma
Familial Mediterranean fever		Chylous ascites