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Topics in Pulmonary Disease

Pleural Effusion

I. Diagnostic evaluation of Pleural Effusion

A. Classification of transudate vs. exudate

1. Criteria for exudate - pleural fluid/serum protein >0.5; pleural

fluid/serum LDH >0.6; or absolute LDH >2/3 upper limits of normal

serum level

2. Implications: transudate related to change in hydrostatic and oncotic

pressure balance; exudate related to change in pleural permeability

B. Cell count

RBCs - bloody effusion suggestive of trauma, malignancy, or pulmonary infarction

Lymphocytes - overwhelming predominance of mature

lymphocytes suggestive of TB. Other potential diagnoses -

lymphoma, sarcoidosis, chronic rheumatoid pleurisy, carcinoma

Eosinophils - most commonly following previous blood or air in pleural space

C. Glucose

Lowest in RA, empyema

Can be low in TB, malignancy, lupus, esophageal rupture

pH

Tends to be low in conjunction with low glucose

Prognostic implication for development of complications (1oculations) in parapneumonic effusion

Definition of chylothorax - triglycerides >110 mg/dl. If borderline

triglycerides (50-110 mg/dl), chylomicrons on lipoprotein

electrophoresis of fluid are diagnostic of chylothorax

Specific causes of pleural effusions

TB - presence of effusions in primary vs. reactivation disease

Cirrhosis - commonly secondary to leakage of ascitic fluid through diaphragmatic defects

D. Pulmonary emboli - any type of effusion possible

E. Drugs - pleuropulmonary disease described in patients taking

bromocriptine for Parkinson's disease; can get effusions, pleural thickening, pulmonary infiltrates

Pleural biopsy

A. Main usefulness when TB suspected

1. Importance of culture and histology of biopsy

B. Less usefulness for supplementing results from pleural fluid cytology

V. Selected aspects of diagnosis and management

B. Sclerosis (pleurodesis) - generally with minocycline or doxycycline

(tetracycline no longer available); can be done through chest tube or small

bore catheter

Pleuroperitoneal shunting - an alternative for palliation of dyspnea if other

therapy not effective or not appropriate

1. May be the treatment of choice for