Lactate dehydrogenase

Transudate < Client’s serum LD

(serum adult norm

45–90 U/L, child

normal 60–170 U/L)

Exudate > Client’s serum LD

pH 7.4

Specific gravity

Transudate < 1.016 < 1.016

Exudate > 1.016 > 1.016

Total protein

Transudate < 2.5 g/dL <25 g/L

Exudate > 3 g/dL > 30 g/L

Volume < 25 mL

White blood cells

Transudate < 100/mm3 < 100 × 0109

/L

Exudate > 1000/mm3 > 1000 × 109

/L

Abnormal Pleural Fluid Accumulation,

or Pleural Effusion may be Caused by

1. Increased capillary permeability due to inflammation;

this typically is associated with increased pleural fluid

protein (over 3 g%).

2. Decreased plasma colloid osmotic pressure due to

hypoproteinemia, this typically is associated with

pleural fluid protein, about 1 g%.

3. Increased hydrostatic pressure due to increased

systemic and/or pulmonary venous pressure, as in

congestive heart failure. Pleural fluid protein concentration is variable in these cases.

4. Decreased lymphatic drainage due to tumor, inflammation, or fibrosis involving mediastinal lymph nodes

(also systemic venous hypertension). This typically is

associated with increased pleural fluid protein (over

3 g%).

Indications for Thoracentesis

1. Effusion of unknown etiology.

2. Effusion of known etiology causing symptoms.

3. Intrapleural instillation of drugs for treatment of

infection or malignancy.

4. Hemothorax or empyema (to prevent organization).

Complications of Thoracentesis may include:

1. Hemopneumothorax due to lung laceration.

2. Mediastinal shift or pulmonary edema (if large

amounts are aspirated at one time).

Do not Remove More than 1 liter of Fluid at One Time

Collect pleural fluid in three sterile anticoagulated EDTA

tubes labeled sequentially: First tube for culture and

Gram’s stain, the rest for cell counts, differential counts,

total protein, glucose, cytology, etc. If malignancy or

tuberculosis is suspected, several hundred mL of anticoagulated fluid should be given for examination.

Gross Examination

Hemorrhagic fluids can be distinguished from traumatic tap

by noting the color of aspirate in the successive tubes filled

with fluid. In traumatic tap the later tubes become clearer.

Hemorrhagic Pleural Fluid Can be Found in

¾ Intrapleural malignancy (60% cases)

¾ Pancreatitis

¾ Pulmonary infarction

¾ Pleural infection

¾ Closed chest trauma

¾ Tuberculosis

¾ Postmyocardial infarction syndrome

¾ Congestive heart failure occasionally

¾ Hepatic cirrhosis.

Hemothorax

Hemothorax can be distinguished from hemorrhagic effusion. Similar PCV of fluid and blood implies

hemothorax. Cloudy, turbid fluid is usually due to large

numbers of leukocytes associated with septic/nonseptic

inflammation.

Milky Fluid

Pseudochylous effusion may occur in:

¾ Tuberculosis

¾ Rheumatoid arthritis, etc.

Cerebrospinal and Other Body Fluids 391

True Chylothorax

True chylothorax is rare, occurs due to leakage of thoracic

duct contents, is creamy fluid with consistency of milk,

which clears and decreases in volume with alkalinization

and ether extraction.

Pleural fluid should be observed for clotting in plain

tube or after adding CaCl2 to EDTA fluid tube. Presence of

fibrinogen suggests damage to capillary walls caused by

inflammation or neoplasm.

Microscopic Examination

This should be done as has been told in CSF examination

(TLC and DLC). A WBC count over 1000/cu mm or over

50% of neutrophils, suggests inflammation (septic or nonseptic). A high percentage of lymphocytes (> 50%) suggests

tuberculosis, lymphoma or carcinoma.

Sometimes lymphocytic effusion may be seen in:

¾ Cardiopulmonary disease

¾ Cirrhosis

¾ SLE

¾ Infectious mononucleosis

¾ Subacute bacterial pulmonary infection.

RA Cells

RA cells may sometimes be seen in rheumatoid pleural

effusions. LE cells may be seen in SLE.

Eosinophilic pleural effusions may be seen in:

¾ Convalescent pneumonia

¾ Pneumothorax

¾ Pulmonary infarction

¾ Hypersensitivity diseases

• Asthma

• Loeffler’s syndrome

• Periarteritis

• Parasitic diseases.

Immature blood cells may be seen in:

¾ Chronic myeloid leukemia

¾ Myeloid metaplasia (extramedullary hemopoiesis).