updates in parapneumonic effusion and empyema
TRANSCRIPT
Updates in Parapneumonic Effusion and Empyema
Gamal Rabie Agmy, MD,FCCP Professor of Chest Diseases, Assiut university
Pneumonias – Classification
• Community Acquired CAP
• Health Care Associated HCAP
• Hospital Acquired HAP
• ICU Acquired ICUAP
• Ventilator Acquired VAP
Nosocomial
Pneumonias
*HCAP: diagnosis made < 48h after
admission with any of the following risk
factors:
(1)hospitalized in an acute care hospital for >
48h within 90d of the diagnosis;
(2) resided in a nursing home or long-term
care facility;
(3) received recent IV antibiotic therapy,
chemotherapy, or wound care within the 30d
preceding the current diagnosis; and
(4) attended a hospital or hemodialysis
clinic
HCAP
"Pleurisy" (syn. pleuritis) is best defined
as an inflammatory process of the pleura,
which can be caused either by a variety of
infectious microorganisms or by other
inflammatory mechanisms. It is usually
associated with localized chest pain that
is synchronous with the respiratory cycle
and is often manifested as a pleural rub
on auscultation..
Definitions
It may induce an exudative pleural
effusion. The pain and the rub sometimes
subside when an effusion develops.
A "parapneumonic effusion" is an
accumulation of exudative pleural fluid
associated with an ipsilateral pulmonary
infection.
Definitions
"Uncomplicated parapneumonic
effusions" are not infected and do not
usually need tube thoracostomy.
"Complicated parapneumonic
effusions" are usually associated with the
pleural invasion of the infectious agent and
require tube thoracostomy and sometimes
decortication for their resolution.
Definitions
"An effusion is called an "empyema"
when the concentration of leucocytes
becomes macroscopically evident as a
thick and turbid fluid (pus). In more than
50% of cases, it is of parapneumonic
origin. Other common causes include
surgical procedures (mainly thoracic
surgery), traumas and oesophageal
perforation
Definitions
The pleuritis sicca stage The inflammatory process of the
pulmonary parenchyma extends to the
visceral pleura, causing a local pleuritic
reaction. This leads to a pleural rub and
the characteristic pleuritic chest pain,
which originates from the sensitive
innervation of the adjacent parietal pleura.
Pathophysiology
The pleuritis sicca stage
A significant number of patients with
pneumonia report pleuritic chest pain
without developing a pleural effusion ,
suggesting that the involvement of the
pleura may be limited to this stage in many
cases of pneumonia..
Pathophysiology
The exudative stage The ongoing inflammatory process leads
to a mediator induced increased
permeability of local tissue and of regional
capillaries. The subsequent accumulation
of fluid in the pleural space is probably the
combined result of the influx of pulmonary
interstitial fluid and of a local microvascular
exudate.
Pathophysiology
The exudative stage
The fluid is usually clear and sterile,
cytological specimens show a
predominance of neutrophils, the pH is
normal and the lactate dehydrogenate
(LDH) activity is <1,000 international units
(IU).
Pathophysiology
The fibropurulent stage This stage may develop quickly (within
hours) in patients who are not receiving
antibiotics, or who are treated with
ineffective antibiotics. It is characterized
by the deposition of fibrin clots and fibrin
membranes ("sails") in the pleural space,
which lead to loculations with increasing
numbers of isolated collections of fluid.
Pathophysiology
The fibropurulent stage It is usually accompanied by (and caused by)
bacterial invasion from the pulmonary
parenchyma. The fluid is often turbid or frank
pus. Cytology shows neutrophils and often
degenerated cells, and Gram stains and
bacterial cultures are usually positive. The
metabolic and cytolytical activity in these
effusions is high, as reflected by low pH values
(<7.2), and high LDH activities (often >1,000
IU).
Pathophysiology
The organizational stage This final stage is characterized by the
invasion of fibroblasts, leading to the
transformation of interpleural fibrin
membranes into a web of thick and
nonelastic pleural peels. Functionally, gas
exchange is often severely impaired on the
side of the organizing empyema ("trapped
lung").
Pathophysiology
The organizational stage
The further course may vary from
spontaneous healing with persistent
defects of lung function to chronic forms of
empyema with high risks for further
complications, such as bronchopleural
fistula, lung abscess, or "empyema
necessitatis" (spontaneous perforation
through the chest wall).
Pathophysiology
The clinical presentation of patients with
pneumonia, whether or not they have
parapneumonic effusions, is similar. there
were no significant differences between
these two groups of patients regarding
white blood cell count (WBC) and the
occurrence of pleuritic chest pain.
Clinical aspects and differential diagnosis
Patients with pneumonia due to infection
with aerobic bacteria usually suffer from an
acute febrile illness, whilst patients with
anaerobic infections tend to present with a
more subacute or chronic condition, with a
longer duration of symptoms and frequent
weight loss
Clinical aspects and differential diagnosis
Anaerobic pleuropulmonary infections
often follow aspiration of oral or gastric
contents. These patients usually have poor
oral hygiene (foetor ex ore!) with anaerobic
colonization of the oropharynx, and often
suffer from conditions that predispose to
aspiration, such as seizure disorders,
syncopes of other origin, or alcoholism.
The latter has been found to be a relevant
associated disorder in as many as 29% to
40% of cases.
Clinical aspects and differential diagnosis
The finding of a purulent effusion without
pneumonia may be explained as a
postpneumonic empyema, in which the
pulmonary infiltrates have already
resolved. However, pleural empyemas are
not necessarily caused by pneumonia.
Clinical aspects and differential diagnosis
The majority of nonpneumonic empyemas
are of iatrogenic origin, most commonly as
a complication of a pneumonectomy or
other thoracic surgical procedures.
Thoracic surgery is responsible for about
20% of all thoracic empyemas Around
5% occur following a thoracic trauma and
5% following an oesophageal perforation
(often iatrogenic).
Clinical aspects and differential diagnosis
The majority of nonpneumonic empyemas
are of iatrogenic origin, most commonly as
a complication of a pneumonectomy or
other thoracic surgical procedures.
Thoracic surgery is responsible for about
20% of all thoracic empyemas Around
5% occur following a thoracic trauma and
5% following an oesophageal perforation
(often iatrogenic).
Clinical aspects and differential diagnosis
Fever, pulmonary infiltrates, and a pleural
effusion are not invariably due to
pneumonia or to a complication of some
surgical procedure. A very important
differential diagnosis, which should always
be considered, is pulmonary infarction.
Clinical aspects and differential diagnosis
Pulmonary embolism is a common disorder
and paraembolic effusions occur in 25–
50% of cases . The effusions may become
infected and will then require treatment
identical to complicated parapneumonic
effusions.
Clinical aspects and differential diagnosis
Other disorders which should be
considered include tuberculosis ,lupus
erythematosus and other autoimmune
disorders , acute pancreatitis and other
diseases of the gastrointestinal (GI) tract [,
and drug-induced pleuropulmonary
disease . The turbid or milky aspect of
empyemas may sometimes lead to the
misconception of a chylothorax or
pseudochylothorax .
Clinical aspects and differential diagnosis
Other disorders which should be
considered include tuberculosis ,lupus
erythematosus and other autoimmune
disorders , acute pancreatitis and other
diseases of the gastrointestinal (GI) tract [,
and drug-induced pleuropulmonary
disease . The turbid or milky aspect of
empyemas may sometimes lead to the
misconception of a chylothorax or
pseudochylothorax .
Clinical aspects and differential diagnosis
Laboratory Studies
No specific laboratory studies of the serum suggest the
presence of a parapneumonic effusion or empyema.
However, the possibility of a parapneumonic effusion
and empyema should be a consideration for every patient
with pneumonia.
The presence of pleural fluid may be suggested based on
physical examination findings; however, small pleural
effusions may not be detected during the physical
examination. In this case, any significant effusion can be
visualized using 2-view (ie, posteroanterior, lateral) chest
radiography.
Laboratory Studies Sputum should be submitted for culture, especially if purulent.
The infecting organism may be suggested based on Gram stain
results. Mixed florae are often seen in anaerobic infections..
As with any infection, leukocytosis may be present (>12,000/µL)
; however, it should decrease with adequate antibiotic therapy.
Persistent fever and leukocytosis despite adequate antibiotic
therapy may signal a persistent focus of infection, such as a
complicated parapneumonic effusion or empyema.
Diagnosing a complicated parapneumonic effusion and/or
empyema is crucial for optimal management because a delay in
drainage of the pleural fluid substantially increases morbidity.
Imaging Studies
Chest radiography:
Lateral chest radiography usually demonstrates the presence of a significant
amount of pleural fluid, as shown in the image below.
Left lateral chest radiograph shows a large,
left pleural effusion.
Imaging Studies
Chest radiography:
If either of the diaphragms is not visible throughout its entire length, the posterior costophrenic angles are blunted, or a lateral meniscus is visible,
then bilateral decubitus chest radiographs should be obtained.
Free pleural fluid is seen as a dense linear shadow layering between the
chest wall and the lung parenchyma.
Unchanging pleural-based linear densities, pleural-based mass-liked
densities, or collections with obtuse angles suggest the presence of
loculated fluid, especially if the differences in the fluid or the appearance
between upright and lateral views are minimal.
If the pleural fluid distance measures more than 10 mm from the chest wall,
sufficient free-flowing fluid is present to perform a diagnostic thoracentesis.
Imaging Studies
Ultrasonography:
Ultrasonography can be used to localize fluid for a
thoracentesis. Fluid appears dark or black on ultrasound
images, and most bedside ultrasonography devices
permit measurement of the depth of location from the
chest wall.
Complex fluid (purulent or viscous) may have more
density or shadows within in the pleural fluid collection.
Sometimes, fibrinous strands can be seen floating in the
pleural fluid.
Other structures such as the diaphragm or lung
parenchyma can provide landmarks to assist in needle
placement for thoracentesis.
Imaging Studies
Ultrasonography:
Loculated pleural effusions may be difficult to localize
during physical examination, but they can usually be
identified with ultrasonography.
Ultrasonography can effectively distinguish loculated
pleural fluid from an infiltrate. The latter may have air
bronchograms visible, but the distinction may be difficult
if a dense consolidation is present.
If a loculated pleural effusion is suspected, an
ultrasonographic examination is recommended for
diagnosis and marking the area for thoracentesis.
Complex nonseptated effusion Complex septated effusion with movable
septa
Complex septated
effusion with
Fixed septa
Imaging Studies CT scanning of the thorax:|
CT scanning of the chest with contrast, as shown in the image below, enhances the pleural surface and assists in delineating the pleural fluid loculations.
CT scan of thorax shows loculated pleural
effusion on left and contrast enhancement
of visceral pleura, indicating the etiology is
likely an empyema.
Imaging Studies CT scanning of the thorax:|
Chest CT scan with intravenous
contrast in a patient with mixed
Streptococcus milleri and anaerobic
empyema following aspiration
pneumonia, showing a thickened contrast-enhanced pleural rind,
high-density pleural effusion,
loculation, and septation.
Thoracentesis yielded foul-smelling
pus.
Imaging Studies CT scanning of the thorax:|
Pleural enhancement can be seen in patients with active inflammation
and severe pleuropulmonary infections, which provides another sign of
the possibility of a complicated pleural effusion or empyema.
CT scanning of the chest may also help detect airway or parenchymal abnormalities such as endobronchial obstruction or the presence
of lung abscesses.
Figure26.24
Simple parapneumonic effusion. The left pleural effusion is… Parapneumonic effusions
Procedures
Thoracentesis is recommended when the suspected
parapneumonic pleural effusion is greater than or equal
to 10 mm thick on a lateral decubitus chest radiograph
Pleural fluid appearance may vary from a clear yellow
liquid to an opaque turbid fluid to grossly purulent thick,
viscous, foul-smelling pus. Foul-smelling fluid indicates
an anaerobic infection.
Pleural fluid studies Blood cell count (WBC count) and differential: Results
generally are not diagnostic, but most transudates are
associated with a WBC counts of less than 1000 cells/µL
and empyemas are exudates, with WBC counts generally
greater than 50,000 cells/µL.
Pleural fluid total protein, LDH, and glucose
(corresponding serum protein and LDH): Exudates are
defined by pleural/serum total protein ratio of greater than
0.5 and a pleural/serum LDH ratio of greater than 0.6 or a
pleural fluid LDH value greater than two thirds the upper
limit of normal. One criterion is sufficient to classify fluid
as an exudate.
Pleural fluid studies Pleural fluid pH (iced blood gas syringe): Values of less
than 7.20 are suggestive of a complicated pleural effusion.
Other laboratories suggestive of complicated pleural
effusion or empyema: These include (1) an LDH value of
greater than 1000 U/L, (2) a pH of less than 7.00, and (3) a
glucose level of less than 40 mg/dL.
Microbiology (Gram stain, bacterial culture): Acid-fast
bacilli and fungal infections may cause pleural effusions or
empyema, but these organisms are more difficult to culture
from pleural fluid.
Histologic Findings
Multiple granulocytes are typically identified on
histologic examination. Necrotic debris may be present.
Bacteria are seen in the pleural fluid in severe infections.
Staging The following classification and treatment scheme has
been used to characterize parapneumonic effusions and
empyema.
Category 1 (parapneumonic effusion): Minimal free-flowing fluid, smaller than 10 mm on decubitus films
Culture, Gram stain, and pH unknown
No thoracentesis needed; treatment with antibiotics alone
Category 2 (uncomplicated parapneumonic effusion): Larger than 10 mm fluid and less than half the hemithorax on
decubitus films
Gram stain and culture negative
pH higher than 7.20
Treatment with antibiotics alone
Staging
Category 3 (complicated parapneumonic effusion):
Large free-flowing effusion, more than half the hemithorax
pH lower than 7.20, LDH level greater than 1000 U/L and glucose
level greater than 40 mg/dL
Gram stain or culture positive
Treatment with tube thoracostomy and antibiotics
Multiloculated effusions may require multiple tubes
Thrombolytics may help resolution
Staging
Category 4 (empyema):
Large free-flowing effusion, greater than equal to half the hemithorax
Loculated effusion or effusion with thickened pleura
Gross pus on aspiration
Treatment with tube thoracostomy
Thrombolytics may help resolution
May require decortication
Medical Care
The initial treatment of a patient with pneumonia and
pleural effusion involves two major decisions. The first
decision involves selection of an appropriate antibiotic
that will cover likely pathogens.
The second decision involves the need for drainage of
pleural fluid and is be guided by the American College of
Chest Physicians (ACCP) guideline recommendations for
the medical and surgical treatment of parapneumonic
effusions.
Medical Care The initial antibiotic selection is usually based on whether the
pneumonia is community or hospital acquired and on the
severity of the patient's illness.
For a patient with community-acquired pneumonia, the
recommended agents are second- or third-generation
cephalosporins in addition to a macrolide.
For patients hospitalized with severe community-acquired
pneumonia, initiate treatment with a macrolide plus a third-
generation cephalosporin with antipseudomonal activity. Enteric
Gram-negative bacilli frequently cause pneumonia acquired in
institutions (eg, hospitals, nursing homes). Therefore, initial
antibiotic coverage should include an antibiotic effective against
pseudomonads. If aspiration is evident or suspected, oral
anaerobic micro-organism should also be covered.
Medical Care Infectious Diseases Society of America (IDSA)/American
Thoracic Society (ATS) consensus guidelines on the
management of community-acquired pneumonia, hospital-
acquired pneumonia, ventilator-associated pneumonia, and
healthcare-associated pneumonia in adults are published
elsewhere.[9, 10] Also seePneumonia, Bacterial.
Effusions with pleural fluid layering less than 10 mm on
decubitus chest radiographs almost always resolve with
appropriate systemic antibiotics. Patients with pleural effusions
that have a pleural fluid layering greater than 10 mm on lateral
decubitus radiographs should have a diagnostic thoracentesis
unless there is a contra-indication to the procedure. If the
diagnostic thoracentesis yields thick pus, the patient has an
empyema thoracis and definitive pleural drainage is absolutely
required. If the pleural fluid is not thick pus, then results of
pleural fluid Gram stain or culture, pleural fluid pH and glucose
levels, and the presence or absence of pleural fluid loculations
should guide the course of action as recommended in the
guidelines.[8]
Of note, the strength of recommendations by the expert panel in
this guideline is somewhat limited because of the small number
of randomized, controlled trials, and methodological weakness
resulted in heterogeneous data. The panel urged review of these
recommendations cautiously; they purposefully avoided specific
recommendations or preferences on primary management
approaches (ie, no drainage, therapeutic thoracentesis, tube
thoracostomy, fibrinolytics, video-assisted thoracoscopic surgery
[VATS], thoracotomy). Despite these limitations, consistent and
possibly clinically meaningful trends formed for the pooled data
and the results of the randomized, controlled trials and the
historically controlled series on the primary management
approach to parapneumonic pleural effusions.
Medical Care Effusions with pleural fluid layering less than 10 mm on
decubitus chest radiographs almost always resolve with
appropriate systemic antibiotics.
Patients with pleural effusions that have a pleural fluid layering
greater than 10 mm on lateral decubitus radiographs should
have a diagnostic thoracentesis unless there is a contra-
indication to the procedure. If the diagnostic thoracentesis yields
thick pus, the patient has an empyema thoracis and definitive
pleural drainage is absolutely required.
If the pleural fluid is not thick pus, then results of pleural fluid
Gram stain or culture, pleural fluid pH and glucose levels, and
the presence or absence of pleural fluid loculations should guide
the course of action as recommended in the guidelines.
Medical Care In summary, the recommendations are as follows: In all patients with acute bacterial pneumonia, the presence of a
parapneumonic pleural effusion should be considered (level C
evidence).
In patients with parapneumonic pleural effusions, the estimated risk
for poor outcome, using the panel-recommended approach based on
pleural space anatomy, pleural fluid bacteriology, and pleural fluid
chemistry, should be the basis for determining whether the
parapneumonic pleural effusions should be drained (level D
evidence).
Poor outcomes could result from any or all of the following: prolonged
hospitalization, prolonged evidence of systemic toxicity, increased
morbidity from any drainage procedure, increased risk for residual
ventilatory impairment, increased risk for local spread of the inflammatory
reaction, and increased mortality.
Surgical Care
Thoracoscopy:
Thoracoscopy is an alternate therapy for multiloculated empyema
thoracis. In patients with multiloculated parapneumonic pleural
effusions, the loculations in the pleural space can be disrupted with
a thoracoscope, and the pleural space can be drained completely. If
extensive adhesions are present or thick pleural peel entraps the
lung, the procedure may be converted to open thoracostomy and
decortication.
Surgical Care
Luh et al published their experience in the treatment of
complicated parapneumonic pleural effusions and empyema
thoracis by VATS in 234 patients (108 women, 126 men).
More than 85% (200 patients) received preoperative
diagnostic or therapeutic thoracentesis, tube thoracostomy, or
fibrinolytics. Of 234 patients, 202 patients (86.3%) achieved
satisfactory results with VATS. Only 40 patients required open
decortication or repeat procedures. VATS is safe and effective
for treatment; earlier intervention with VATS can produce
better clinical results
Surgical Care
Hope et al reviewed outcomes of surgical treatment for
parapneumonic empyema thoracis. The use of VATS was
compared with thoracotomy. Morbidity and mortality rates
were similar among all groups. The conversion rate to open
thoracotomy was 21%. Based on a shorter postoperative
length of stay with similar morbidity and mortality in patients
operated on within 11 days of admission, early aggressive
surgery treatment for complicated parapneumonic effusions or
empyema thoracis is recommended.
Surgical Care Retrospective evaluation of 2 different surgical procedures
(decortication vs debridement) and approaches (VATS vs
thoracotomy) were analyzed by Casali and colleagues. VATS
debridement had a lower postoperative hospital stay and
shorter duration of chest drainage and greater improvement in a
subjective dyspnea score. The long-term spirometric evaluation
was normal in 58 patients (56%). Age older than 70 years old
was the only variable associated with poor long-term results
(forced expiratory volume in 1 second [FEV1] < 60% and/or
dyspnea Medical Research Council grade ≥2) at multivariate
analysis. VATS is associated with less postoperative mortality
and shorter postoperative hospital stay.
Surgical Care Rib resection and open drainage of pleural space:
Open drainage of the pleural space may be used when closed-
tube drainage of the pleural infection is inadequate and the
patient does not respond to intrapleural thrombolytic agents.
This procedure is recommended only when the patient is too ill
to tolerate decortication. The resection of one to three ribs
overlying the lower part of the empyema thoracis cavity is
performed, a large-bore chest tube is inserted into the
empyema thoracis cavity, and the tube is drained into a
colostomy bag.
Surgical Care
Decortication:
In decortication, all the fibrous tissue is removed from
the visceral pleural peel, and all pus is evacuated from
the pleural space. Decortication is a major thoracic
operation requiring full thoracotomy; therefore,
decortication is not tolerated by critically ill patients.
Decortication is the procedure of choice for patients in
whom pleural sepsis is not controlled by closed-tube
thoracostomy, intrapleural thrombolytic agents, and,
possibly, thoracoscopy. Mortality rates as high as 10%
have been described with this procedure.
Surgical Care
Decortication:
Decortication should not be performed solely to
remove the thickened pleural peel; the thickened
pleural peel usually resolves over several months. If
the pleura remains thickened with symptom-limiting
reduction in pulmonary function after approximately 6
months, decortication can be considered.
Surgical Care Postpneumonectomy empyema thoracis:
an uncommon but life-threatening complication, is
often associated with a bronchopleural fistula.
Treatment of bronchopleural fistula depends on
several factors, including the extent of dehiscence,
degree of pleural contamination, and general condition
of the patient. Early diagnosis and aggressive
therapeutic strategies for controlling infection, closing
the fistula, and sterilizing the closed pleural space are
mandatory. Repeated debridement, VATS, endoscopic
application of tissue glue, and stenting may be
additional management strategies..
