Download Pleural fluid collections in critically ill patients

Pleural fluid collections in
critically ill patients
Elankumaran Paramasivam MRCP
Andrew Bodenham FRCA
Key points
Pleural fluid collections are
common in the critically ill;
they are predominantly
transudates that do not
require drainage unless
compromising respiration.
Relying on protein content for
diagnosis of pleural effusion
may be misleading; estimation
of pH should be performed if
infection is suspected.
Bedside ultrasound provides
more reliable confirmation of
effusions and their
approximate volume than
chest X-ray.
Seldinger small bore drains are
safe and less painful than
traditional large bore drains.
Prior verification of a
collection by imaging will avoid
needle damage to the lung.
Blood in the pleural space
(haemothorax) is normally
related to trauma or surgical
interventions and requires
early drainage and possibly
surgical exploration.
Elankumaran Paramasivam MRCP
Specialist Registrar in Intensive Care
Medicine and Respiratory Medicine
Anaesthetic Department
Leeds General Infirmary
Leeds LS1 3EX
UK
Andrew Bodenham FRCA
Consultant Anaesthetist and Director of
Intensive Care Unit
Anaesthetic Department
Leeds General Infirmary
Leeds LS1 3EX
UK
Tel: 0113 3922321
Fax: 0113 3928431
E-mail: [email protected]
(for correspondence)
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Pleural effusion is defined as the excessive
accumulation of fluid in the pleural space, indicating an imbalance between pleural fluid formation
and removal. The presence of a pleural effusion
may be a primary manifestation or a secondary
complication of many disorders. A subsequent
review will cover air leaks and pneumothorax.
Pathophysiology
The inner surface of the chest wall and the
surface of the lungs are covered by the parietal
and visceral pleura, respectively, with a 10–
24 mm separation normally between the two surfaces. This space is usually filled with a very
small amount of fluid. However, large amounts
(4–5 litres in an adult) of fluid can accumulate in
the pleural space under pathological conditions.
The parietal pleura has sensory innervation.
Both pleural surfaces are mainly supplied by systemic arterial vessels. Lymphatic vessels from the
parietal pleura drain to lymph nodes along the
anterior and posterior chest wall; lymphatics from
the visceral surface drain to the mediastinal
lymph nodes. The pleural space typically contains
a small amount of a colourless alkaline fluid
(0.1–0.2 ml kg21, pH 7.62), which has a low
amount of protein (,1.5 g dl21). Approximately
90% of accumulated fluid in the pleural space is
drained by the venous circulation; the other 10%
is absorbed by the lymphatics.
A delicate balance between the oncotic and
hydrostatic pressures of the pleural space regulates
filtration and drainage of pleural fluid. Net absorption of pleural fluid is slightly greater than net
filtration forces. In addition, lymphatic drainage
from the parietal pleura can surpass the rate of
fluid filtration in the pleural space. Chest wall and
diaphragmatic movements also enhance absorption of pleural fluid by the vascular and lymphatic
vessels. Excessive filtration of fluid can overwhelm these efficient absorptive mechanisms and
lead to the formation of pleural effusion.
Types of fluid collections
Pleural effusions are traditionally classified as
either transudates or exudates. Diseases that
affect the filtration of pleural fluid result in
transudate formation and often occur bilaterally. Inflammation or injury increases pleural
capillary membrane permeability to proteins
and various types of cells and lead to the formation of an exudative effusion.1
Blood in the pleural space (haemothorax) is
normally related to trauma or surgical interventions and requires early drainage, plus consideration for surgical exploration for control of
bleeding. In chest trauma, an initial drainage of
1500 ml or . 200 ml h21 is an indication for
surgical exploration.2 Early drainage is essential
before clotting occurs as thereafter only serum
will drain leaving residual clot. If extensive, this
will cause mechanical problems and may become
infected. Importantly, blood clot will not drain
effectively through a fine bore drain; surgical
decortication via thoracotomy may be required.
Collection of lymphatic fluid (chyle) in the
chest from disruption of the major lymphatic
trunks is a rare but recognized problem after surgical procedures such as oesophagogastrectomy
and trauma. The drained fluid is characteristically milky if the patient is on enteral feeding.
Management is initial drainage and institution of
total parenteral nutrition to reduce the volume of
losses and provide nutrition. Persistent large
volume losses for .10 days are an indication for
surgical correction of the leak.3
Chyliform or pseudochylous pleural effusions
grossly resemble chylothorax. However, these
effusions contain no chylomicrons and pathogenesis does not involve the thoracic duct. There is a
high lipid content (cholesterol crystals or lecithin–
globulin complexes) causing a milky white appearance. Pseudochylous pleural effusions occur
commonly with longstanding pleural effusions
and are associated with rheumatoid pleuritis.
Causes of pleural effusions
Each case of pleural effusion must be evaluated
on an individual basis. Knowledge about its
prevalence in underlying illnesses can be of
help in developing the differential diagnosis
(Table 1). A flow chart for the diagnosis of
pleural effusion is shown in Fig. 1.
Continuing Education in Anaesthesia, Critical Care & Pain | Volume 7 Number 1 2007
& The Board of Management and Trustees of the British Journal of Anaesthesia [2007].
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Pleural fluid collections
and non-productive cough. Physical findings are reduced tactile
fremitus, dullness on percussion, and diminished or absent breath
sounds. A pleural rub may also be heard during inspiration during
the early phase of inflammation. Even large pleural effusions can
often remain asymptomatic and present as incidental findings.
Pulmonary function tests show a restrictive ventilatory defect and
reduced functional residual capacity. In the intensive care unit
(ICU) setting they are difficult to detect on clinical examination
alone due to patient positioning and chest wall oedema.
Table 1. Types of pleural effusion with associated conditions
Transudates
Common
Congestive heart failure
Nephrotic syndrome
Cirrhosis with ascites
Peritoneal dialysis
Less common
Urinothorax
Pulmonary embolism
Myxoedema
Exudates
Parapneumonic effusion
Malignancy
Pulmonary embolism
Collagen vascular disease
Subphrenic abscess
Pancreatitis
Tuberculosis
Postcardiac injury syndrome
Chylothorax
Uraemia
Oesophageal perforation
Asbestos-related disease
Drug-induced reactions
Viral infection
Yellow nail syndrome
Sarcoidosis
Imaging
Chest radiography
Symptoms and signs
Symptoms depend upon the amount of fluid and the
underlying cause. These include pleuritic chest pain, dyspnoea,
Standard posteroanterior and lateral chest radiography remains the
most important technique for the initial diagnosis of pleural effusion. The classical signs of pleural effusion on erect chest X-ray
are blunting of the costo-phrenic angle, homogeneous opacification
with no air bronchograms and a meniscus with the apex towards
the axilla (Fig. 2A). On supine chest radiography (commonly used
in ICU), moderate-to-large pleural effusions may escape detection
because the pleural fluid settles posteriorly and no change in the diaphragm or lateral pleural edges may be noted. In these cases, a
Fig. 1. Flow chart for diagnosis of pleural effusion.
Continuing Education in Anaesthesia, Critical Care & Pain j Volume 7 Number 1 2007
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Pleural fluid collections
Fig. 3. Ultrasound image of a sagittal view of a right-sided pleural effusion
with the probe in the infraaxillary region. The markings indicate the
thickness of the fluid layer between the inferior margin of the collapsed
lung and the chest wall.
Computerized tomography scanning
Computerized tomography (CT) scans for pleural effusions should
be performed with contrast enhancement. In simple uncomplicated
pleural effusions, the CT scan shows crescent-shaped opacities in
the posterior and basal portions of the hemi-thorax (Fig. 4A). In
cases of difficult drainage, CT scanning should be used to delineate the size and position of loculated effusions (Fig. 4B). CT scanning may also be used to differentiate between benign and
malignant pleural thickening.
Laboratory tests
Fig. 2. (A) Erect chest X-ray showing right pleural effusion with the classic
signs of costo-phrenic angle obliteration, and meniscus with the apex
towards the axilla. (B) Supine chest X-ray showing a moderate right-sided
pleural effusion in a ICU patient with homogenous opacification of the
lower zone and preserved vascular markings.
After obtaining a sample of pleural fluid, the clinician should
determine whether the effusion is a transudate or exudate. If the
fluid is a transudate, the possible causes are relatively few and
further diagnostic procedures are not necessary. In contrast, if the
fluid is an exudate, further diagnostic tests are required.
Light’s criteria
pleural effusion must be suspected when there is increased opacity
of the hemithorax without obscuring of the vascular markings
(Fig. 2B). In large pleural effusions there is a complete white out
of the hemithorax. Mediastinal shift to the opposite side along
with a visible lung margin will differentiate it from collapse of the
lung due to endobronchial obstruction. If an effusion is suspected
but not clear on plain chest X-ray, ultrasonography should be
performed.
Ultrasonography
The classical appearance of a pleural effusion is an echo-free layer
between the visceral and parietal portions of the pleura (Fig. 3).
The nature of the fluid and presence of loculations can be seen.
The volume of an effusion can be estimated from measurements of
dimensions of an effusion in various planes or by measuring the
width between the lower lung margin and diaphagm.4
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Transudative and exudative pleural effusions are differentiated by
comparing protein and lactate dehydrogenase concentrations in the
pleural fluid to those in the blood. Exudative pleural effusions
meet at least one of the following criteria, whereas transudative
pleural effusions meet none:
(i) the ratio of pleural fluid protein to serum protein is . 0.5;
(ii) the ratio of pleural fluid lactic dehydrogenase (LDH) and
serum LDH is . 0.6;
(iii) pleural fluid LDH is more than two-thirds normal upper limit
for serum.
The sensitivity for exudate is 98% and specificity 83% with the above
criteria. Twenty-five per cent of patients with transudative pleural effusions are mistakenly identified as having exudative pleural effusions
by the above criteria.5 Additional testing is therefore needed if a
patient identified as having an exudative pleural effusion appears clinically to have a condition likely to produce a transudative effusion.
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Pleural fluid collections
Amylase concentration
A high pleural amylase concentration (.200 U dl21) occurs both
in acute and chronic pancreatitis, malignancy, or oesophageal
rupture. The clinical setting usually separates these entities and
assay of isoenzymes can be helpful (salivary vs pancreatic source)
(Table 2).7
Management of pleural effusions
Diagnosis vs treatment
The management of pleural effusions in ICU patients with respiratory failure remains controversial. All pleural effusions associated
with pneumonic illness should be aspirated for diagnostic investigation.8 Quantitative assessment of the volume of pleural effusions
is crucial to select critically ill patients for thoracentesis.
Tap vs drain
Fig. 4. (A) Supine CT of the thorax showing bilateral pleural effusions
appearing as crescent-shaped opacities in the posterior hemithorax.
(B) Computerized tomogram of the thorax showing a large multi-loculated
left pleural effusion with pleural enhancement. The left lung is markedly
collapsed.
Pleural fluid characteristics remain the most reliable diagnostic test
to guide management. The presence of frankly purulent or turbid/
cloudy fluid on pleural aspiration indicates the need for prompt
chest-tube drainage, as is the presence of organisms identified by
positive Gram staining. Thereafter, pleural fluid pH is the most
useful index predicting the need for chest-tube drainage and the
pleural LDH and glucose concentration do not further improve
diagnostic clarity in parapneumonic effusions. Routine preprocedure checks of platelet count, prothrombin time, or both are
only required in those patients with known risk factors. Fluid collections greater than a litre associated with respiratory compromise
should be considered for drainage, irrespective of their nature.
Which drain?
Glucose concentration
The glucose concentration in transudates and most exudates is
similar to that of serum. The conditions that cause low pleural
fluid glucose concentrations are rheumatoid arthritis, tuberculosis, empyema, and malignancies with extensive pleural
involvement.
Studies have shown that the small catheters (10– 14 Fr) are often
as effective as larger bore tubes and are more comfortable and
better tolerated by the patient.9 There are no large randomized
control trials directly comparing small and large bore tubes. In the
event of failure to drain a pneumothorax due to excessive air
leakage, it is recommended that a larger bore tube is inserted. On
the basis of clinical experience, large bore tubes are more effective
for draining thick pus and blood.
pH
The pH of normal pleural fluid is approximately 7.62 owing to
active transport of HCO2
3 into the pleural space. A low pH is seen
in inflammatory and infiltrative processes such as infected parapneumonic effusions, empyema, malignancies, collagen vascular
disease, and oesophageal rupture. Urinothorax is the only transudative effusion that can present with a low pleural fluid pH. A parapneumonic pleural fluid with pH , 7.2 indicates a poor patient
outcome and requires drainage.6
Table 2. Laboratory tests on pleural fluid for differential diagnosis. The choice of
the test depends on the clinical condition
All effusions
Exudates
Other tests
Protein
LDH
pH
Cell count
Cholesterol
Gram stain/culture
Fungal stain/culture
Acid-fast stain and culture
Cytological analysis
Glucose
Amylase
Antinuclear antibody titre
Triglycerides
Albumin
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Pleural fluid collections
Which bottle?
The chest tube is attached to a drainage system that allows one
direction of flow only. This is the closed underwater seal bottle in
which a tube is placed under water at a depth of approximately
3 cm with a side vent which allows escape of air, or it may be connected to a suction pump. The respiratory swing in the fluid in the
chest tube is useful for assessing tube patency and confirms the
position of the tube in the pleural cavity. The use of integral
Heimlich flutter valves are advocated in patients with pneumothorax as they permit ambulatory or even outpatient management and have been associated with a 85 –95% success rate. A
drainage bag with an incorporated flutter valve and vented outlet
has been successfully used postoperatively.
Suction
High-volume, low-pressure suction pumps are used in persistent
pneumothorax and following chemical pleurodesis. However, there
is no evidence to support their routine use in the initial treatment
of spontaneous pneumothorax. If suction is required, this should be
performed via the underwater seal at a level of 10–20 cm of water.
Wall suction is effective but chest drains must not be connected
directly to the high negative pressure available from wall suction.
Removing the drain
The timing of drain removal is dependent on the original reason
for insertion and clinical progress. In cases of haemothorax, the
drain should not be removed until it completely ceases to drain;
however, for transudates, it should be left until it reduces to insignificant quantities (approx. 50 –100 ml in 24 h). Clamping of the
drain before removal is unnecessary. The chest tube should be
removed either while the patient performs a Valsalva’s manoeuvre
or during expiration. A brisk firm movement is required with an
assistant tying the previously placed closure suture.
Further management issues
Blocked chest tubes should be flushed with 20 –50 ml normal
saline to ensure patency. Contrast-enhanced CT scanning is the
most useful imaging modality in patients for whom chest-tube
drainage has proved unsuccessful; it provides anatomical details
such as loculations and ensures accurate tube placement. All
patients with pleural infections should have an assessment of the
effectiveness of the pleural fluid drainage along with resolution of
sepsis 5– 8 days after chest-tube insertion and commencement
of antibiotics. For an empyema, there are no objective criteria to
define the point at which a patient should be referred for surgery.
Patients with purulent fluid and loculations are more likely to
require surgical drainage. Failure of sepsis to resolve within 7 days
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has been suggested as an appropriate period after which a surgical
opinion should be sought. A number of surgical approaches are
available including video-assisted thoracoscopic surgery, open
thoracic drainage, or thoracotomy and decortication. The type of
procedure performed will depend on many factors including
patient age, co-morbidity and surgical preference.
Re-expansion pulmonary oedema
Re-expansion pulmonary oedema occurs following rapid evacuation of large pleural effusions and during decompression of spontaneous pneumothorax.10 The two main factors involved are
alteration of capillary permeability and increase of hydrostatic
pressure.11 Mild symptoms suggestive of re-expansion oedema are
common after large volume thoracentesis in pleural effusion with
patients experiencing discomfort and cough. It is recommended
that no more than approximately 1.5 litres should be drained at any
one time or drainage should be slowed to ,500 ml h21.
References
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476– 81
2. Weil PH, Margolis IB. Systematic approach to traumatic hemothorax.
Am J Surg 1981; 142: 692–4
3. Mallick A, Bodeham AR. Disorders of the lymph circulation: their relevance to anaesthesia and intensive care. Br J Anesth 2003; 91: 265– 72
4. Eibenberger KL, Dock WI, Ammann ME, Dorffner R, Hormann MF,
Grabenwoger F. Quantification of pleural effusions: sonography versus
radiography. Radiology 1994; 191: 681 –4
5. Light RW, MacGregor MI, Luschsinger PC, Ball WC. Pleural effusions:
the diagnostic separation of transudates and exudates. Ann Intern Med
1972: 62: 57– 63
6. Davies CW, Kearney SE, Gleeson FV, Davies RJ. Predictors of outcome
and long-term survival in patients with pleural effusion. Am J Resp Crit
Care Med 1999; 160: 1682– 7
7. Sherr HP, Light RW, Merson MH, Wolf RO, Taylor LL, Hendrix TR.
Origin of pleural fluid amylase in oesophageal rupture. Ann Inter Med
1972; 76: 985–6
8. Davies CWH, Gleeson FV, Davies RJO. British Thoracic Society guidelines for the management of pleural infection in adults. Thorax 2003;
58(Suppl. 2): 18– 28
9. Clementsen P, Evald T, Grode G, Hansen M, Krag Jacobsen G,
Faurschou P. Treatment of malignant pleural effusion: pleurodesis
using a small bore catheter. A prospective randomized study. Respir
Med 1998; 92: 593–6
10. Henderson AF, Banham SW, Moran F. Re-expansion pulmonary oedema;
a potentially serious complication of delay in diagnosis of pnemothorax.
BMJ 1985; 29: 593 –4
11. Mahajan VK, Simon M, Huber GL. Reexpansion pulmonary oedema.
Chest 1979; 75: 192– 4
Please see multiple choice questions 8 –11
Continuing Education in Anaesthesia, Critical Care & Pain j Volume 7 Number 1 2007