Pleural
Effusions - Introduction, Signs & Symptoms, Diagnosis Techniques,
Types of Fluids & Draining Pleural Effusions
(September 21st, 2008)
 Pleural
Effusions is the accumulation of excess fluids in the pleural cavity,
which inhibits the normal expansion/contraction of the lungs and
can impair breathing. Normally, very small amounts of fluids are
present around the pleural spaces and are generally not detectable.
The Pleura is a Sac which houses the lungs, and consists of a thin
membrane called the 'mesothelium.' The mesothelium is a vital part
of the lungs because it enables them to expand and contract when
breathing by secreting a fluid. This fluid is located in the lungs
and inside of the rib cage. The official definition of pleural effusions
is that it occurs when the rate of fluid formation exceeds the rate
of fluid absorption, resulting in excess fluids clogging up the
lungs and causing pulmonary signs and symptoms. Normal human beings
have the capacity of 20-25ml of fluids in each pleural space. Fluids
enter the pleural space via the capillaries in the parietal pleura
or through the peritoneal cavity through small holes in the diaphragm.
Excess fluids that have not been absorbed are normally removed by
lymphatics in the parietal pleura that have the capacity to absorb
upto 20 times more fluid than is produced. When this capacity is
overwhelmed, pleural effusions develops.
Types of Pleural Effusion Fluids
 There
are 4 common types of pleural fluids that can develop. They are:
i) Serous fluid - Serous fluid is benign, meaning it is not cancerous.
It appears transparent and has a typical pale yellow look.
ii) Blood - Blood is a specialized body fluid with a makeup of
dissolved proteins, glucose, hormones, carbondioxide, mineral ions
and red blood cells. Blood typically appears red.
iii) Chylothorax - Chylothorax is a milkish bodily fluid that consists
of free fatty acids, emulsified fats and lymph particles.
iv) Pus (Pyothorax) - Pus is a yellowish-whitish substance that
is produced when the body goes through inflammatory reactions. Accumulation
of pus around the pleura is known as an abscess.
Signs & Symptoms of Pleural Effusions
Pressure on the chest, chest pain, dyspnea (difficulty breathing)
and excessive cough are some of the common symptoms of pleural effusions.
Excessive pleural fluids can cause intense inflammation of the pleural
surfaces and acute pain for the patient. If the pleural effusions
is between the 500-1500 ml range, this causes chest pressure. If
the effusions is greater than 1500 ml, this can cause dyspnea which
is a difficulty in breathing. Dyspnea rarely occurs when the fluid
in the pleura is low, thus a difficulty in breathing signals doctors
that there are excess fluids in the lungs. Dyspnea occurs not only
when the patient is active such as running or jogging, but it can
also occur when the patient is relaxing or sleeping.
Diagnosis of Pleural Effusions
 The first step
to diagnose pleural effusions is a chest x-ray that shows fluids
building up around the pleural spaces. A physical examination of
the patient is conducted on the basis of medical history. In order
to diagnose the patient with pleural effusions, the medical doctor
must be able to detect atleast 300mL of fluids using upright chest
films. If the level of fluids exceeds 500mL, this indicates clinical
signs in the patient such as diminished breath sounds, decreased
vocal reflection, etc. Once a pleural effusion is diagnosed, the
cause of it must be concluded and this is done via a thoracentesis.
A needle is inserted through the chest wall into the pleural space
to extract a sample fluid, which is then tested for the following
properties:
i) Chemical compositions such as proteins, albumin, amylase, glucose
and pH.
ii) Bacterial cells to detect any bacterial infections
iii) Count # of cells
iv) Cytology or the study of cells to identify any malignant cells
v) Other required tests to make a conclusive diagnosis
Draining a Pleural Effusion
 Drainage
is a treatment option for pleural effusions and involves slowly
draining out the fluids from the chest to relieve the patient off
symptoms. The doctor asks the patient to to sit either on a chair
or on the edge of the bed and to lean forward so that the back is
exposed. The doctor will then decide exactly what part of the back
he will inject the needle. Before that, the skin over the area where
the drain is to be inserted is cleaned with an antiseptic solution
to prevent it from becoming infected. The doctor then gives the
patient a dose of local anaesthetic to prevent the process from
becoming painful.
After the chest area has been anesthetised, the doctor will make
a very small cut into the chest and insert a needle called a cannula.
The cannula is connected to a tube and drainage bag that will collect
all the fluids extracted from the chest. If the amount of fluid
is greater than 500mL, the patient will need to stay in the hospital
for atleast 2 days so that all fluid coming out is drained. This
means the cannula will be stitched to the chest area for that period
of time. Once the drainage has slowed down, doctors will take a
chest x-ray to see if the lungs have expanded again. If so, the
doctors will remove the cannula and the patient can return home.
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