Consider a differential diagnosisbeyond empyema when managing a pleural effusion
Consider a differential diagnosisbeyond empyema when managing a pleural effusion: Excerpt from Avoiding Common Pediatric Errors
Author:
Craig DeWolfe, MD
What to Do - Interpret the Data
Although the most common etiology for a pleural effusion in the pediatric
population is an empyema, its differential diagnosis is broad and the consequences of mismanaging one are significant. A practitioner should consider
malignancy, congestive heart failure, autoimmune, and nephrotic processes,
among others listed below, when confronted with an effusion. A careful history and physical examination, in addition to an appropriate workup and
laboratory approach when considering the underlying pathophysiology, will
prevent most diagnostic errors.
The work of breathing and diminished breath sounds found in pleural effusions, owing to the altered flow and absorption of pleural fluid with
resultant compression of the lung, are universal. The confounding symptoms of the effusion, however, are often different because of the speed of
fluid accumulation, the patient's cardiopulmonary reserve, and the associated symptoms of any underlying disease. In the case of pneumonia or other
systemicinflammatoryprocesssuchasaconnectivetissuedisease,fluidaccumulates becauseoftheincreasedcapillarypermeabilityof vesselsandoncotic
pressure of proteins in the pleural space. These patients present with systemic symptoms of inflammation, such as fever and myalgia, in addition to
cough or arthritis. In congestive heart failure, the capillary hydrostatic pressure is increased and results in bilateral effusions. Neonates with congenital
heart disease commonly present as afebrile, cyanotic, with poor perfusion,
and have a murmur. In older patients with congestive heart failure caused by
a previously compensated and/or undiscovered congenital disorder, myopathy, myocarditis, pericarditis, or pericardial effusion, the associated symptoms include fatigue, failure to thrive, tachycardia, hepatosplenomegaly, and
poor perfusion. Malignancies that result in mediastinal lymphadenopathy
or obstruction of the lymphatic ducts, such as in lymphoma or superior vena
cava syndrome, prevent lymphatic drainage from the pleural space and often manifest with more indolent fever, weight loss, night sweats, or facial
edema. Patients with effusions resulting from nephrotic syndrome with its
associated hypoalbuminemia and low plasma oncotic pressure present with
dependent edema—commonly of the extremities, perioral or scrotal areas.
Finally,patientswhopresentwithtrauma,pancreatitis,orDown'sorNoonan
syndrome should be considered at risk for evolving effusions.
Radiographs are crucial in the diagnosis and management of pleural effusions. The practitioner should first use posteroanterior and lateral
plain film radiographs in order to measure the effusion and identify associated parenchymal or cardiac disease. Lateral decubitus films should then
be obtained to assess for mobile fluid. In the case of nonloculated effusions, placing the unaffected side inferior may also help the practitioner
visualize the underlying parenchyma. Practitioners should avoid obtaining
a supine film—common in portable x-rays when the patient is considered
too sick to transfer—as effusions may manifest as diffuse haziness and be
overlooked. Ultrasounds and computed tomography are second line studies
for the practitioner concerned with managing a significant effusion. Ultrasounds differentiate solid versus liquid lesions with 92% accuracy and can
often facilitate a thoracentesis so that fluid is obtained with the least amount
of radiation exposure and risk to the patient. Chest computed tomographic
scans are invaluable to surgeons when the predominance of evidence suggests an empyema and the extent of loculations and presence of an abscess
will help them determine their surgical approach.
When pleural effusions are not clearly related to pneumonia, a thoracentesis will allow the clinician to evaluate the pleural fluid and either
make the diagnosis or limit the differential. Gross visualization of the fluid
may identify pus (suggestive of a bacterial process), chyle, blood, or fluid
that can be further characterized as an exudate or transudate. An exudate
suggests an inflammatory process that disrupts the integrity of the pleural
lining and allows the movement of inflammatory cells and other proteins
across the pleura. Alternatively, a transudate results from a pressure gradient across an intact lining and is characterized by a relative paucity of
cells with chemistries similar to serum. The clinician should order a protein
level, glucose, lactase dehydrogenase (LDH), cell count, and culture when
differentiating a transudate from an exudate, whereas cytology, pH, amylase,
triglyceride, or antinuclear antibody may be helpful for further classification.
The Light's criteria for diagnosing an exudate include any one of the following: (a) the ratio of pleural protein to serum protein is >0.5, (b) the ratio
of pleural LDH to serum LDH is >0.6, or (c) the ratio of pleural LDH to
the upper limit of normal for serum is 2/3. If the fluid is an exudate, the
clinician should consider bacteria, tuberculosis, virus, neoplasm, connective
tissue, pancreatitis, esophageal perforation, or pulmonary infarction high on
the differential. If the fluid is a transudate, the differential diagnosis includes
congestive heart failure, nephrotic syndrome, cirrhosis, peritoneal fluid, or
hypothyroidism. A milky fluid suggests a chylothorax from an injury to the
lymphaticchannelfromaneoplasm,surgery,tuberculosis,orcongenitalchylothorax. A bloody fluid in the absence of trauma suggests malignancy, lung
infarction, or postpericardiotomy syndrome.
The degree of symptoms and pathology will determine the extent of
intervention, which includes close monitoring without further drainage,
intermittenttherapeuticthoracentesis,orplacementofatubewithorwithout
surgical thoracotomy. Any patient with respiratory compromise attributed
to the effusion should have the fluid drained. In addition, a grossly purulent
fluid suggestive of an empyema should be drained with a chest tube because
of the high likelihood of developing loculations, pleural peel, or other tissue
injury.Furtheruseofantibiotics,diuretics,anti-inflammatorydrugs,orother
therapeutic measures is dictated by the ultimate diagnosis.
In summary, not all pleural effusions are empyemas, but with the appropriate clinical suspicion, thorough history, exam, and logical diagnostic
approach, the clinician will avoid most therapeutic mishaps or delays.
Suggested Readings
Boyer DM. Evaluation and management of a child with a pleural effusion. Pediatr Emerg Care.
2005;21:63–68.
Montgomery M, Sigalet D. Air and liquid in the pleural space. In: Chernick V, Boat TR,
Willmont RW, et al., eds. Kendig's Disorders of the Respiratory Tract in Children. 7th ed.
Philadelphia: Saunders; 2006, chapter 21.
Book Source Details
- Book Title: Avoiding Common Pediatric Errors
- Author(s): Anthony D Slonim MD, DrPH; Lisa Marcucci MD
- Year of Publication: 2008
- Copyright Details: Avoiding Common Pediatric Errors, Copyright © 2008 Lippincott Williams & Wilkins.
More About Pleural effusion
More Medical Textbooks Online about Pleural effusion
Review other book chapters online related to Pleural effusion:
Medical Books Excerpts
- Pleural Effusion
- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
- [ read ]
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Avoiding Common Pediatric Errors
Authors: Anthony D Slonim MD, DrPH; Lisa Marcucci MD
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7489-6
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